Nickel-based super alloy: Inconel 600 (UNS N06600)

What is inconel 600?

Nickel-based super alloy: Inconel 600 (UNS N06600) is an early developed nickel-chromium-iron-based solid solution Reinforced alloy, has good high temperature corrosion resistance and oxidation resistance, excellent cold and hot processing and welding process performance, and has satisfactory thermal strength and high plasticity below 700 ℃. The alloy can be strengthened by cold working, or it can be connected by resistance welding, melt welding or brazing, and can be supplied with cold rolled sheet, hot rolled thick plate, strip, wire, bar, round cake, ring blank, ring forging, etc., It is suitable for the production of anti-oxidation parts which can bear low load under 1100℃.
Designated as UNS N06600 or W.Nr. 2.4816, Inconel 600, also known as alloy 600, is a nickel-chromium-iron alloy with good oxidation resistance at high temperatures and resistance to chloride ion stress-corrosion cracking, corrosion by high-purity water, and caustic corrosion. It is mainly used for furnace components, in chemical and food processing, in nuclear engineering, and for sparking electrodes. Inconel 600 (76Ni-15Cr-8Fe) is the basic alloy in the Ni-Cr-Fe system in which the high nickel content makes it resistant to reducing environments.

  • Material grade: Inconel 600 (N06600) nickel-based alloy.
  • Inconel600 similar grades: GH600, GH3600 (China).

Table of Contents hide

inconel 600 seamless pipes 1 1 - Nickel-based super alloy: Inconel 600 (UNS N06600)

ASTM B167 Inconel 600 seamless pipes 1″ SCH80

Chemical Composition of Inconel 600 (UNS N06600)

Ni C Mn Cr S Si Fe
Max 0.15 1 17 0.015 0.5 10
Min 72 14 6

Mechanical Properties of Inconel 600 (UNS N06600)

Ultimate Tensile Yield Strength (0.2% OS) Elong. in 2 in. or 50mm or 4D, min., % R/A Hardness
Cold Worked/As worked
Min 110 KSi 85 KSi 10
Max
Min 760 MPa 585 KSi
Max
Hot Worked/As Worked
Min 90 KSi 40 KSi 25
Max
Min 620 MPa 275 MPa
Max
D- Forging quality is furnished to chemical requirements and surface inspection only. No mechanical properties required.

Technical standards specify the properties: see Table 1-1.
Table 1-1

Variety θ/℃ Tensile properties HBS Bending test
σ b /MPa σ P0.2 /MPa δ 5 /% φ/%
Bar 20 ≥585 ≥240 ≥30 134~217
Round cake, ring blank or ring piece 20 ≥520 ≥205 ≥35 ≥187
Hot rolled plate 20 ≥550 ≥240 ≥35 ≥40
900 ≥95 ≥45 ≥40 ≥50
Cold rolled sheet 20 ≥550 ≥240 ≥30
900 ≥90 ≥40 ≥60
Cold rolled sheet 20 ≥550 ≥200 ≥30 test
Strip 20 ≥550 ≥240 ≥30
Wire 20 Measured Measured Measured HV≤151 Cold upsetting qualified
  • ① The plate in the supply state should be subjected to a room temperature bending test.

The diameter of the core rod is equal to the product thickness multiplied by the bending coefficient in Table 1-2. The bending axis should be parallel to the rolling direction.
Table 1-2

Product thickness/mm <0.25 0.25~1.30 >1.30~4.00
Bending coefficient Mutual agreement 1 2

Physical Properties of Inconel 600 (UNS N06600)


Density Melting Range Specific Heat Curie Temperature Electrical Resistivity
lb/in3 Mg/m3 °F °C Btu/lb-°F J/kg-°C °F °C mil/ft μΩ-m
0.306 8.47 2470-2575 1354-1413 0.106 444 -192 -124 620 1.03

inconel 600 rod 55mm 1.6m 1 - Nickel-based super alloy: Inconel 600 (UNS N06600)

ASTM B166 Inconel 600 Round Bar O.D=65mm, Length=1.9m

Thermal Properties of Inconel 600 (UNS N06600):

(1) Melting temperature range: 1370~1430℃ .
(2) Thermal conductivity: see Table 2-1.
Table 2-1 

θ/℃ 20 100 200 300 400 500 600 700 800 900 1000
λ/(W/(m·℃)) 12.85 13.94 15.15 16.62 18.71 20.72 22.40 24.49 27.0 29.51 31.60

(3) Linear expansion coefficient: see Table 2-2.
(4) Density of Inconel600: ρ=8.43g/cm 3.

Electrical properties of Inconel 600 (UNS N06600):

Resistivity is shown in Figure 2-2.

Table 2 – 2

θ/℃ 20~200 20~300 20~400 20~500 20~600 20~700 20~800 20~1000
α/10 -6 ℃ -1 12.35 12.75 13.10 13.55 14.50 15.15 15.70 16.20

Magnetic properties of Inconel 600 (UNS N06600):

The alloy is non-magnetic.

Chemical performance of Inconel 600 (UNS N06600):

Anti-oxidation performance: the oxidation rate of 100h tested in air medium is shown in Table 2-3.

20200819035730 37601 - Nickel-based super alloy: Inconel 600 (UNS N06600)

Table 2-3

θ/℃ 800 900 1000
Oxidation rate/(g/m 2 ·h) 0.01865 0.05724 0.13718

Structure of of Inconel 600 (UNS N06600):

After the alloy is treated at 1120℃ for 2h, only TiN nitrogen and compounds of Cr.7 C.3 type carbide in the aging by long 1500h, is still 870 ℃ tissue of Cr.7 C.3 and TiN, described microstructure of the alloy is stable.

Modulus of Elasticity of Inconel 600

Temp. °F -325 -200 -100 70 200 300 400 500 600
E 33.3 32.5 31.9 31 30.3 29.9 29.4 29 28.6
Temp. °F 700 800 900 1000 1100 1200 1300 1400 1500
E 28.1 27.6 27.1 26.5 25.9 25.3 24.6 23.9 23.1

  • *E: the modulus of elasticity at given temperature, unit: 106 psi.
  • *The poisson’s ratio of Alloy 600 is 0.31 and its density is 0.300 lb/in3.

Thermal Conductivity and Diffusivity of Inconel 600

Thermal Conductivity of Inconel 600 at Elevated Temperatures

Temp. °F 70 100 150 200 250 300 350 400 450 500
TC 8.6 8.7 8.9 9.1 9.3 9.6 9.8 10.1 10.3 10.6
Temp. °F 550 600 650 700 750 800 850 900 950 1000
TC 10.8 11.1 11.3 11.6 11.8 12.1 12.4 12.6 12.9 13.2
Temp. °F 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500
TC 13.4 13.7 14 14.3 14.6 14.9 15.2 15.5 15.8 16

  • *TC: the coefficient of thermal conductivity, unit: Btu / hr-ft-°F.

Thermal Diffusivity of Inconel 600 at Elevated Temperatures

Temp. °F 70 100 150 200 250 300 350 400 450 500
TD 0.154 0.154 0.155 0.156 0.158 0.16 0.163 0.165 0.168 0.17
Temp. °F 550 600 650 700 750 800 850 900 950 1000
TD 0.172 0.175 0.177 0.179 0.181 0.183 0.184 0.186 0.188 0.189
Temp. °F 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500
TD 0.191 0.192 0.194 0.196 0.197 0.199 0.201 0.204 0.206 0.208

  • *TD: the coefficient of thermal diffusivity, unit: ft2 / hr.

All values are in conformance with ASME BPVC Section II Part D physical properties of UNS N06600.

Thermal Expansion Coefficients of Inconel 600

The thermal expansion coefficients of Inconel 600 (UNS N06600) at elevated temperatures are listed in below table:

Temperature, °F Coefficient A Coefficient B Coefficient C
70 6.8 6.8 0
100 7 6.9 0.2
150 7.2 7 0.7
200 7.4 7.1 1.1
250 7.6 7.2 1.6
300 7.7 7.3 2
350 7.9 7.4 2.5
400 8 7.5 3
450 8.2 7.6 3.5
500 8.3 7.6 3.9
550 8.4 7.7 4.4
600 8.5 7.8 5
650 8.6 7.9 5.5
700 8.7 7.9 6
750 8.8 8 6.5
800 8.9 8 7

  • *Coefficient A: the instantaneous coefficient of thermal expansion, unit: 10-6 (inch/inch/°F).
  • *Coefficient B: the mean coefficient of thermal expansion in going from 70°F to indicated temperature, unit: 10−6 (inch/inch/°F).
  • *Coefficient C: the linear thermal expansion in going from 70°F to indicated temperature, unit: inch /100 ft.
  • *All values are in conformance with ASME BPVC Section II Part D Properties (Customary).

Process performance and requirements of Inconel 600 (UNS N06600):

Formability of inconel600:

The alloy has good hot workability, the heating temperature for ingot forging is 1110~1140℃; the final forging temperature is not less than 950℃, slab rolling The heating temperature for the system is 1130 to 1170°C, and the heating temperature for finishing rolling is 1090 to 1130°C. The solution treatment temperature of the finished product is 1010~1050℃.

Welding performance of inconel600:

Alloy welding performance is good, it can be connected by various methods such as arc welding, argon arc welding, resistance welding and brazing. Large or complex welded structural parts should be annealed at 870℃ for 1h after fusion welding to eliminate Welding stress.

Heat treatment process of Inconel600 parts:

The heat treatment process of parts should be carried out according to the heat treatment system of the corresponding material standard. The annealing treatment of sheet and strip parts should be carried out in a protective atmosphere.

Specifications of Inconel 600 (UNS N06600)

Form Standard
Metal Type UNS N06600
Bar ASTM B166 AMS 5665 Din 17752
Wire
Sheet ASTM B168 AMS 5540 Din 17750
Plate ASTM B168 AMS 5540 Din 17750
Tube ASTM B167
Pipe ASTM B167
Fitting ASTM B366
Forging ASTM B564 Din 17754
Weld Wire FM 82/ ERNiCr-3
Weld Electrode FM 182/ ENiCrFe-3
Din 2.4816

Machining of Inconel 600 (UNS N06600)

Carbide tools are suggested
For Rates Better Than 50% Of Type 304.
Machining Type Suggested starting rates are:
Single Point Turning : Roughing – 0.15″ depth, 0.015″/rev feed -175 SFM
Finishing – 0.025″ depth, 0.007″/rev feed – 200 SFM
Drilling : 1/4″ Dia hole – 0.004″/rev feed – 60 SFM
1/2″ Dia hole – 0.007″/rev feed – 60 SFM
3/4″ Dia hole – 0.010″/rev feed – 60 SFM
Reaming : Feed – same as drilling – 100 SFM
Side And Slot Milling : Roughing – 0.25″ depth – 0.007″/tooth feed – 125SFM
Finishing – 0.050″ depth – 0.009″/tooth feed – 140SFM
These rates are for carbide tools,
Type C-2 For Roughing, Drilling And Reaming.
Type C-3 For Finishing.

Machinability Ratings of Inconel 600 (UNS N06600)

GRADE
APPROXIMATE SURFACE
RELATIVE SPEED
FEET PER MINUTE BASED ON C-1212
A-286 54 28
L-605 15 9
Nickel 200 110 66
Monel 400 80 48
Monel R405 80 48
Monel K500 60 36
 K500 Aged 40 25
600 50 22
625 20 12
718 20 12
X-750 20 12
Waspaloy 45 20
MP 35N 45 20
MP 159 45 20
C-276 40 18
Hast X 45 20
These machinability ratios must be recognized as approximate values.  They are a reasonable guide to relative tool life and lower required for cutting.  It is obvious, however, that variables of speed, cutting oil, feed and depth of cut will significantly affect these ratios.

The Machinability of Inconel 600

Inconel 600 alloys (UNS N06600) may be machined to pipe fittings, flanges, valve parts and other complex shapes. The investigation on Inconel 600’s machinability is introduced in this article. The main machining/ cutting methods include drilling, boring, turning, grinding, and milling, etc.

Inconel 600’s Machining Characteristics

  • Large cutting forced and high cutting temperature, usually 1.5~2 times than carbon steel.
  • The serious wear of cutting tools results in very short service life.
  • Serious work hardening during the machining.
  • Very difficult to dispose the chips during machining process.

Selection of Cutting Tools

a sanvik turning tool for inconel 600 machining - Nickel-based super alloy: Inconel 600 (UNS N06600)

A Sandvik turning tool for Inconel 600’s machining.

The cutting tools for Inconel 600 shall be very sharp while maintain adequate strength. In practice, the fine grain hard alloy with TiC-TiN or TiC-Al2O3-TiN coating is the prime option. Typical brand: VNGP160408 S05F from Sandvik Coromant. Another option is the ceramic cutting tools with its representative brand Sialon Si3N4 RNGN120700KY2100.

Cutting Parameters and Cutting Fluid

The empirical cutting parameters during the machining of Inconel 600:

  • Cutting speed: 20 m/minute ~ 80 m/minute.
  • Cutting feed: 0.1 mm/r ~ 0.3 mm/r.
  • Back engagement: 0.3 mm ~ 5 mm.
  • Rake angle: 3°~10°, clearance angle: 8°~15°.
  • Tool cutting edge inclination angle: 0°~4°.
  • Edge chamfer angle: 0°~5°, Edge width: 0.2 mm ~ 0.4 mm.
  • Spiral angle(end mill): 28°~35°.

Both aqueous solution or chlorinated oil can be chosen as the cutting fluid.

Characteristics of Inconel 600 (UNS N06600)

  • Ni-Cr-Iron alloy,solid solution strengthening. 
  • Good resistance to high temperature corrosion and oxidation resistance. 
  • Excellent hot and cold processing and welding performance. 
  • A satisfactory heat intensity and high plasticity until 700℃. 
  • Can be strengthened through the cold work,also can use resistance welding,welding or soldering connection.

Corrosion resistance of Inconel 600 (UNS N06600)

  • Corrosion resistance to all kinds of corrosive media.
  • Chromium compounds make the alloy have better corrosion resistance than nickel 99.2 (200) alloy and  nickel (alloy 201,low carbon) under the condition of oxidation.
  • At the same time,the high content of nickel alloy shows  good corrosion resistance in alkaline solution and in reduction conditions,and can effectively prevent the chloride-iron stress corrosion cracking.
  • Very good corrosion resistance in acetic acid,acetic acid, formic acid,stearic acid and other organic acids,and corrosion resistance in inorganic acid media.
  • Excellent corrosion resistance in a nuclear reactor in primary and secondary circulation use of high purity water.
  • Particular prominent performance is the ability to resist dry chlorine and hydrogen chloride corrosion, application temperature can be up to 650℃.At high temperature,the alloy of annealing and solid solution treatment states in air has the very good antioxidant performance and high peeling strength.
  • The alloy also shows resistance to ammonia and nitriding and carburizing atmosphere, but in the REDOX conditions changed alternately alloy will be influenced by partial oxidation corrosion media.

Heat treatment system:

  • Plate: 1010~1050℃, 3~5min/mm, air cooling; 
  • Strip: 1010℃±10℃, air cooling; wire: 1065℃±10℃, air cooling.
  • Bars and rings are subjected to 1010℃±10℃, air cooling and solid solution treatment.

Melting and casting process:

The alloy is smelted by one of the following processes:

  • (1) Non-vacuum induction melting and electroslag remelting;
  • (2) Electric arc furnace smelting and electroslag remelting;
  • (3) Vacuum melting.

ASTM B166 Inconel 600 Wire

The Inconel 600 wire refers to an ASTM B166 UNS N06600 cold-worked wire which has uniform round cross section along its whole length, supplied in coil form. They can be further woven into wire mesh or wire cloth which are widely used for filter, conveyor belt, or heat-treatment furnace. Inconel 600 wires are usually wrapped on a spool in different lengths.

astm b166 inconel 600 wire cold drawn - Nickel-based super alloy: Inconel 600 (UNS N06600)

ASTM B166 Inconel 600 (UNS N06600) wires wrapped onto the spool.

Manufacture Processes of Inconel 600 Wires

cold drawing process for fabrication of inconel 600 wire - Nickel-based super alloy: Inconel 600 (UNS N06600)

The cold drawing process for the manufacture of Inconel 600 wires.

Generally, ASTM B166 UNS N06600 wires shall be fabricated by the following processes: Mid-frequency Vacuum Induction Furnace (or Electric Arc Furnace) → Electroslag Remelting → Forging → Rolling → Cold Drawing → Heat Treatment → Cleaning → Packaging & Storage.

Chemical Composition Requirements of Inconel 600 Wire

Nickel [Ni] Chromium [Cr] Iron [Fe] Manganese [Mn] Carbon [C] Copper [Cu] Silicon [Si] Sulfur [S]
≥72.0 14.0~17.0 6.0~10.0 ≤1.0 ≤0.15 ≤0.50 ≤0.50 ≤0.015
  • *All values shall be in weight percentage unit.

Conditions, Sizes & Mechanical Properties of Inconel 600 Wire

Size, inch [mm] Condition Tensile Strength, ksi [MPa]
d<0.032 [0.81] Annealed 80~115 [552~793]
d≥0.032 [0.81] Annealed 80~105 [552~724]
All Sizes Regular Tempered ≥120 [827]
d≤0.057 [1.45] Sring Tempered ≥185 [1276]
0.057< d ≤0.114
[1.45< d ≤2.90]
Sring Tempered ≥175 [1207]
0.114< d ≤0.229
[2.90< d ≤5.82]
Sring Tempered ≥170 [1172]
0.229< d ≤0.329
[5.82< d ≤8.36]
Sring Tempered ≥165 [1138]
0.329< d ≤0.375
[8.36< d ≤9.53]
Sring Tempered ≥160 [1103]
0.375< d ≤0.500
[9.53< d ≤12.7]
Sring Tempered ≥155 [1069]
0.500< d ≤0.560
[12.7< d ≤14.3]
Sring Tempered ≥140 [965]
  • Properties are not applicable to wire after straightening or cutting.

The Welding of Inconel 600 Materials

We have engaged in the fabrication of a chemical regenerator for a 160,000 ton/ year propylene project in Chile. The design temperature is 600°C and the design pressure is 35/70 kPa. The medium includes oxygen, air, chlorine, carbon monoxide and carbon dioxide. Considering the severe corrosive environments, Inconel 600 is selected as the main material of the regenerator. A plurality of Inconel 600 plates made of ASME SB-168 Gr. N06600 shall be jointed together by welding process. The welding of Inconel 600 flanges(ASME SB-564 Gr. N06600) and tubes(ASME SB167 Gr. N06600) are also required.

regenerator for propylene project made of inconel 600 - Nickel-based super alloy: Inconel 600 (UNS N06600)

The G.A drawing of a chemical regenerator for a propylene project in Chile. Main material: Inconel 600 plates.

Welding Characteristics of Inconel 600

Generally, preheating is not required for Inconel 600 welding. However, when the base metal temperature is lower than 15°C, the joint area of two sides with a length of 250 mm ~ 300 mm shall be preheated to 15°C ~ 20°C to avoid blow holes resulting from moisture condensing. In order to prevent the grain growth and carbide precipitation, inter-pass temperature shall be no higher than 100°C. Cautions shall be taken to prevent rapid cooling which may result in porosity. The welding area shall be carefully cleaned before welding operation.

the welding of inconel 600 shells of the regenerator - Nickel-based super alloy: Inconel 600 (UNS N06600)

The welding of Inconel 600 shell of main body of the regenerator.

Due to the poor flowability of molten nickel alloy, the slope of bevel ends in jointing area shall be sharp. The welding pool of Inconel 600 is comparatively shallow which may result in incomplete penetration. Medium intensity of welding current and rapid welding are recommended. The coefficient of linear thermal expansion of Inconel 600 is high and it is quite susceptible to hot cracking. Thus, heat input during the welding shall be rigorously controlled.

Welding Methods, Welding Electrodes & Welding Variables

Welding methods and electrode selection for Inconel 600:

  • Shielded Metal Arc Welding (SMAW): AWS 5.11 ENiCrFe-3, Φ4.0 mm; Actual chemical composition of ENiCrFe-3 (%): C-0.087, Si-0.77, Mn-6.60, S-0.005, P-0.015, Cr-17.00, Ni-66.70, Mo-0.07, Cu-0.09, Nb-1.69.
  • Tungsten Inert Gas Welding (TIG): AWS 5.14 ERNiCr-3, Φ2.0 mm; Actual chemical composition of ERNiCr-3 (%): C-0.046, Si-0.30, Mn: 5.50, S: 0.004, P-0.005, Cr-15.62, Ni-64.26, Mo-0.09, Cu-0.02, Nb-1.66.

Other welding variables includes:

Welding Method Welding Current
A
Welding Voltage
V
Welding Rate
mm/min
Polarity Inter-Pass
Temp. °C
Argon Rate
L/min
SMAW 120~140 22~24 180~200 DCEP 15~100
TIG 110~130 15~17 100~110 DCEN 15~100 8~10
  • *The welding procedure qualification(WPQ) shall be conducted as per ASME BPVC Section IX.

Applications of Inconel 600 (UNS N06600)

Inconel600 alloy is a Ni Cr Fe based solid solution strengthening alloy. It has good high temperature corrosion resistance, oxidation resistance, excellent cold and hot processing and welding properties. It has satisfactory thermal strength and high plasticity below 700 ℃.
Inconel 600 has mature use experience abroad, and has been made into aerospace engine parts in China. It has passed the flight test and is also used in aviation.

  • Piping system, water purification system, marine engineering and hydraulic piping perfusion system.
  • The pipeline, joint, air systems in the acidic gas production.
  • Evaporator, the heat exchanger, filter, mixer, etc. in the phosphate production.
  • Power plants condensation and pipe system in the use of sewage water to cool water.
  • The use of acidic organic catalyst chlorinated derivatives production.
  • The production of cellulose pulp,Polished bar in the orrosive oil wells.
  • Hose system in the oceanngineering,Flue gas desulphurization system components.
  • Sulfuric acid condensation and separation system,Crystalline salt concentration and the evaporator.
  • Transport of corrosive chemicals containers,Reverse osmosis desalination plan.
  • Heat exchange tubes
  • Pipe fittings
  • Flanges
  • Valves

Pressure-Temperature Ratings for Inconel 600 Flanges

Inconel 600 flanges manufactured to ASME B16.5 are usually made from two forms of raw material: ASTM B564 UNS N06600 forgings or ASTM B168 UNS N06600 plates (only blind or plate flanges can be made of Inconel 600 plates; the material shall be furnished in annealed condition). According to the standard, the pressure-temperature ratings can be furnished in two unit systems: ISO and US customary.

asme b16 5 inconel 600 flanges wn rtj dn80 - Nickel-based super alloy: Inconel 600 (UNS N06600)

ASTM B564 UNS N06600 (Inconel 600) ASEM B16.5 flange, weld neck, RTJ, DN80 SCH40 Class 600.

Pressure-Temperature Ratings for Inconel 600: ISO Unit

  • *Working pressures by classes, unit: bar.

Pressure-Temperature Ratings for Inconel 600: US Customary Unit

  • *Working pressures by classes, unit: psig.

Variety specifications and supply status of Nickel-based super alloy: Inconel 600 (UNS N06600)

Variety classification: Yaang Pipe Industry can produce various specifications of Inconel600 seamless pipeInconel600 steel plateInconel600 round bar, Inconel600 forgings, Inconel600 flange, Inconel600 ring, Inconel600 welded pipe, Inconel600 pipe fitting, Inconel600 wire and Inconel600 matching welding consumables.

Delivery status:

  • Seamless pipe: solid solution + acid white, length can be fixed;
  • Plate: solid solution, pickling, trimming;
  • Welded pipe: solid solution acid white + RT% flaw detection, forging: annealing + car polish;
  • Bars are forged and rolled, surface polished or car polished;
  • Strips are delivered after cold rolling, solid solution and soft state, and deoxidized;
  • Wires are finely ground in solid solution pickled disk or straight strips, solid solution straight strips delivery in light state.

Intergranular Corrosion Test for Inconel 600 Flanges and Fittings

inconel 600 flanges and pipe fittings 1 - Nickel-based super alloy: Inconel 600 (UNS N06600)

Inconel 600 Slip on flanges and butt-weld pipe fittings supplied to the UK.

Recently, we have supplied a batch of Inconel alloy 600 forged flanges and butt welding pipe fittings to a client from the U.S..

All materials were solution treated at temperatures between 1050°C and 1100°C. Considering its corrosive service environment, intergranular corrosion test should be performed in accordance with ASTM G28.

intergranular corrosion test equipment 1 - Nickel-based super alloy: Inconel 600 (UNS N06600)

Lab apparatus for intergranular corrosion test of nickel alloys.

ASTM G28 specifies standard test methods for detecting susceptibility to intergranular corrosion in wrought, nickel-rich, chromium-bearing alloys. According to purchase specification, method A, ferric sulfate – sulfuric acid test was conducted. 6 pieces of Inconel alloy 600 specimens, with the same heat number as the flanges and fittings, were prepared. They were immersed into the test solution for 24 hours. Mass losses were measured and recorded for further calculation of corrosion rates. The corrosion rates finally determined are: 0.46, 0.42, 0.53, 0.35, 0.32, and 0.33 mm per year. The data all fall in the range of acceptance criteria.

Inconel 600 Used in Wet Air Oxidation System for Spent Caustic Treatment

In a petrochemical refinery, large amount of spent caustic will be discharged from the sweetening process of liquefied petroleum gas(LPG). The spent caustic, often in caustic sludge form, is a severe pollutant to the environment. Generally, a wet air oxidation (WAO) system is introduced subsequently for further treatment. The WAO system consists of reactor, compressor, several heat-exchangers, and some piping accessories. The heat-resistant & corrosion-resistant nickel alloy inconel 600 is the critical material for all the equipment components.

wet air oxidation wao system introduced for spent caustic treatment in a lpg plant - Nickel-based super alloy: Inconel 600 (UNS N06600)

A wet air oxidation(WAO) system for spent caustic treatment which is subsequent to the sweetening equipment in a LPG plant, Qatar.

In the reactor, the WAO process can not only convert the sulfide to sulfate, but also convert organic contaminants to carbon oxide, water and biodegradable short chain organic acids. Heat exhangers are routinely employed to recover the heat energy from reactor effluent.

Yaang has supplied a set of Inconel 600 piping materials for the refurbishment of the wet air oxidation apparatus in Qatar. The refurbishment must be conducted since an Inconel 600 elbow’s failure was founded near the outlet of the reactor.

original piping design of wao system reactor outlet - Nickel-based super alloy: Inconel 600 (UNS N06600)

The original piping design of the reactor outlet of WAO system.

As illustrated above, originally, the reactor is communicated with a short length of 2″ SCH160 Inconel 600 seamless pipe at its outlet which is subsequently connected to 2″ SCH40 pipeline via a flange joint. The reactor effluents flow through the two 90° elbows to the heat exchanger. The design pressure and design temperature are 12 MPa and 300°C respectively. After working for approx. 3240 hours, a crack of 8mm-length was discovered on the first 90° elbow. After comprehensive analysis, engineers conclude that different pipe wall thickness (section) between “before” and “after” the flange joint may cause drastically flow-rate increase which then results in accelerated erosion at the elbow. The inappropriate design must be revised:

revised piping design of reactor outlet of wao system - Nickel-based super alloy: Inconel 600 (UNS N06600)

The revised piping design of reactor outlet of the WAO system.

All the pipeline shall be furnished in SCH160 wall thickness. A 180° 3D return bend is introduced to displace the two 90° elbows with an additional flange joint. The materials supplied by Yaang includes:

  • Inconel 600 welding neck flanges, ASTM B564 UNS N06600, 2″ Class 900 SCH160, raised face, 4 pieces.
  • Inconel 600 return bend (R=3D, 180°), ASTM B366 WPNCI, seamless, 1 piece.
  • ASTM B167 UNS N06600 seamless pipes, 2″ SCH160, BW, length=6m, 4 pieces.

Titanium Content & Precipitated Phases in Inconel 600

Recently, we have supplied Inconel 600 seamless tubes of Φ46 mm x 3 mm to a heat-exchanger manufacturer in Germany. The tubes are made in accordance with ASTM B163 UNS N06600. The manufacturing process of the Inconel 600 tubes is: Non-VIM for raw material → electroslag remelting (ESR) → blooming (Φ95 mm) → hot piercing (Φ98 mm x 8.5 mm) → precision cold-rolling (to Φ46 mm x 3 mm) → heat treatment at 1050°C for 20 minutes(in protective atmosphere) → chemical & mechanical inspection → ultrasonic test → cleaning → packaging & storing. Since there are small amount of titanium additions during raw material melting procedure, a tailored test was conducted to determine its precipitated phase within the alloy.

Test Specimens Preparation

Take two small test pieces from the Inconel 600 tube and cut them off along the axial. Then, grind and polish the surface carefully. Specimen A is dipped in boiling sulfuric acid and potassium permanganate solution which is used for SEM analysis. Specimen B is prepared for extraction replica in carbon film and TEM analysis. The actual chemical composition for the specimen (mass fraction %): C-0.013, Si-0.0008, Mn-0.53, S-0.013, P-0.009, Ni-75.4, Cr-15.22, Cu-0.02, Fe-8.39.

SEM Analysis on Specimen A

sem x135 inconel 600 microstructure - Nickel-based super alloy: Inconel 600 (UNS N06600)

A-1: Microstructure of Inconel 600 by SEM X135(magnification factor)

sem x1350 microstructure of inconel 600 - Nickel-based super alloy: Inconel 600 (UNS N06600)

A-2: Microstructure of Inconel 600 by SEM X1350(magnification factor).

Pictures A-1 and A-2 show the microstructure of Inconel 600 by SEM at 135 and 1350 magnification factors respectively. As shown on A-1, UNS N06600 is a typical austenitic solid-solution alloy with crystal basis of γ austenite. The grain size is approx. 80~100 μm (grain grade 5~6). It is obvious on picture A-2 that there is hardly any precipitated phase at the grain boundaries while some tiny precipitated phases exist within the crystal grain.

sem x540 precipitated phase of inconel 600 - Nickel-based super alloy: Inconel 600 (UNS N06600)

A-3: precipitated phase in Inconel 600 grain taken by SEM X540.

sem x1350 precipitated phase of inconel 600 - Nickel-based super alloy: Inconel 600 (UNS N06600)

A-4: precipitated phase in Inconel 600 grain taken by SEM X1350.

The precipitated phases within the Inconel 600 grain are marked as “1” and “2” on the SEM pictures A-1 and A-2 respectively. The precipitated phase 1 is sphere-shaped while phase 2 is rectangular-shaped. Their energy spectrum are shown in below two pictures respectively. Despite of minor difference in shape, the energy spectrum implies clearly that the chemical composition of phase 1 and phase 2 are almost the same. And the titanium content is very high.

energy spectrum of phase 1 - Nickel-based super alloy: Inconel 600 (UNS N06600)

The energy spectrum of precipitated phase 1.

energy spectrum of phase 2 - Nickel-based super alloy: Inconel 600 (UNS N06600)

The energy spectrum of precipitated phase 2.

Extraction Replica & TEM Analysis on Specimen B

extraction replica of inconel 600 in carbon film - Nickel-based super alloy: Inconel 600 (UNS N06600)

B-1: the extraction replica of Inconel 600, TEM photo.

tem energy spectrum of precipitated phase 3 of inconel 600 - Nickel-based super alloy: Inconel 600 (UNS N06600)

B-2: The energy spectrum of precipitated phase 3 in Inconel 600 grain.

The precipitated phases within the Inconel 600 grain are extracted as replica in carbon film. Photo B-1 is taken by TEM and the energy spectrum of precipitated phase 3 is presented in photo B-2. There are 3 precipitated phases on the replica with identical shapes which implies that the same phase. As shown on B-2, the main constituent of phase 3 is titanium and there is also noticeable amount of chromium. Since there is no nitrogen content, it is concluded that titanium carbide with small amount of chromium carbide is the main constituent of the precipitated phase within Inconel 600 crystal grains.

Solution Treatment & Properties of Inconel 600 Forgings

Generally, Inconel 600 forgings shall be manufactured in conformance with ASTM B564 UNS N06600. In order to investigate the chemical composition and mechanical properties under different conditions, test specimens sized of Φ20 mm x 200 mm(L) are prepared from the original 300 mm x 200 mm Inconel 600 forgings. The solution treatment is conducted on each test piece at different temperatures from 850°C to 1050°C, cooled by air or cold water respectively.

inconel 600 flanges 300lb wn - Nickel-based super alloy: Inconel 600 (UNS N06600)

Typical Inconel 600 forgings: W/N RF flange, 300# SCH 80, 12″ ASME B16.5

Actual Chemical Composition

Ni Cr Fe Mn C Cu Si S P Co
75.2 16.1 7.56 0.001 0.055 0.017 0.18 0.002 0.0016 0.011

*All values are in % unit; The Inconel 600 materials are procured from the Special Metal Division of AnSteel.

Grain Size and Hardness

Solution Treatment
Temperature, °F
Grain Size Hardness
HB
850 5 185
900 4~5 180
950 5+ 229
1000 4 201
1050 4 170
  • *The grain size and hardness of Inconel 600 forgings under different solution-treatment temperature conditions.
  • *Grain size test shall be conducted in accordance with ASTM E-112.

Tensile Properties Tested At Room Temperature (Air Cooling)

*S.T.T Yield Strength
MPa
Tensile Strength
MPa
Elongation
%
Reduction of Area
%
850 326 635 47.5 66.5
900 320 655 45.0 69.0
950 366 690 45.0 69.0
1000 320 650 45.5 69.0
1050 270 620 46.0 77.0
  • *S.T.T: solution treatment temperature; The tensile properties of Inconel 600 forgings tested at room temperature under air cooling condition.

Tensile Properties Tested At 350°C (Air Cooling)

*S.T.T Yield Strength
MPa
Tensile Strength
MPa
Elongation
%
Reduction of Area
%
850 201 575 45.5 63.0
900 189 580 49.0 61.0
950 222 615 51.0 65.0
1000 189 580 52.5 64.5
1050 173 580 60.0 70.5
  • *S.T.T: solution treatment temperature; The tensile properties of Inconel 600 forgings tested at 350°C under air cooling condition.

Tensile Properties Tested At Room Temperature (Water Cooling)

*S.T.T Yield Strength
MPa
Tensile Strength
MPa
Elongation
%
Reduction of Area
%
850 330 650 46.0 63.5
900 310 650 47.0 67.0
950 356 670 44.5 73.5
1000 330 662 45.5 68.5
1050 290 620 44.0 77.5
  • *S.T.T: solution treatment temperature; The tensile properties of Inconel 600 forgings tested at room temperature under water cooling condition.

Tensile Properties Tested At 350°C (Water Cooling)

*S.T.T
°C
Yield Strength
MPa
Tensile Strength
MPa
Elongation
%
Reduction of Area
%
850 209 575 45.0 63.0
900 208 580 46.5 63.0
950 215 605 44.0 65.0
1000 216 605 52.0 64.5
1050 186 575 55.5 68.0
  • *S.T.T: solution treatment temperature; The tensile properties of Inconel 600 forgings tested at 350°C under water cooling condition.

Effect of Solution Treatment Temperature on Properties of Inconel 600

Here, we continue to study on the solution treatment conducted at different temperatures for Inconel 600 specimens. Solution treatment not only has effect on microstructure of Inconel 600 specimens (elaborated in last article) but also has effect on the hardness and corrosion resistance of the material.

Specimen Solution Treatment Temp. Corrosion Rate Hardness
No. °C mm/y HV10
1 950 0.43 177
2 1000 0.54 180
3 1050 0.63 182
4 1100 0.49 167
5 1150 0.76 139
6 1200 0.36 126

  • *The 6 pieces of Inconel 600 plate (specimen) are solution treated at 950°C, 1000°C, 1050°C, 1100°C, 1150°C, and 1200°C respectively.
  • *The hardness value is expressed in Vickers hardness.
  • *The corrosion rate is tested in accordance with ASTM G28 Method A: Ferric Sulfate- Sulfuric Acid Test.

(1) If Inconel 600 is solution treated at a temperature under 1050°C, the hardness will keep stable and almost the same. When it is higher than 1050°C, the hardness will get lower as the temperature goes higher.

(2) After solution treatment, Inconel 600 has exceptional resistance to intergranular corrosion. Especially, if the solution treatment is carried out at 1100°C, carbides may completely dissolve in austenitic matrix. In conclusion, the recommended solution-treatment temperature for Inconel 600 is 1050~1100°C.

Effect of Solution Treatment Temperature on Microstructure of Inconel 600

Inconel 600 Specimen Preparation

In order to study the effect of solution treatment at different temperatures on Inconel 600 material, a piece of 16mm-thick plate of ASTM B168 UNS N06600 is selected as the specimen which is then cut into 6 pieces of 4mm-thick plates. The Inconel 600 plate was manufactured by the following processes in sequence: electric arc furnace(EAF) – argon oxygen decarburization(AOD) – eletroslag remelted – hot rolling – annealing – descaling.

The Actual Chemical Composition of the Inconel 600 Plate (Specimen)
C Mn Fe S Si Cu Ni Cr
0.07% 0.30% 8.9% 0.001% 0.1% 0.1% 73.0% 16.7%
  • *All values are measured by weight.

The Solution Treatment Process

The 6 pieces of Inconel 600 specimens were heated to the temperature 950°C, 1000°C, 1050°C, 1100°C, 1150°C, and 1200°C, respectively, and holding for 5 minutes, respectively, before quenched in cold water.

Microstructure Examination after Solution Treatment

After solution treatment, the microstucture of each specimen is examined utilizing the digital microscope. Their photos are shown below:

microstructure of inconel 600 after solution treatment at 950%C2%B0C - Nickel-based super alloy: Inconel 600 (UNS N06600)

Microstructure of Inconel 600 specimen after solution treated at 950°C.

microstructure of inconel 600 after solution treatment at 1000%C2%B0C - Nickel-based super alloy: Inconel 600 (UNS N06600)

Microstructure of Inconel 600 specimen after solution treated at 1000°C.

microstructure of inconel 600 after solution treatment at 1050%C2%B0C - Nickel-based super alloy: Inconel 600 (UNS N06600)

Microstructure of Inconel 600 specimen after solution treated at 1050°C.

microstructure of inconel 600 after solution treatment at 1100%C2%B0C - Nickel-based super alloy: Inconel 600 (UNS N06600)

Microstructure of Inconel 600 specimen after solution treated at 1100°C.

microstructure of inconel 600 after solution treatment at 1150%C2%B0C - Nickel-based super alloy: Inconel 600 (UNS N06600)

Microstructure of Inconel 600 specimen after solution treated at 1150°C.

microstructure of inconel 600 after solution treatment at 1200%C2%B0C - Nickel-based super alloy: Inconel 600 (UNS N06600)

Microstructure of Inconel 600 specimen after solution treated at 1200°C.

It is obvious that after being solution-treated at 1100°C, the Inconel 600 nickel alloy forms single phase austenite (with twins available) which also means carbides completely dissolve into the austenite matrix. It is also found that the grain size of austenite doesn’t grow up apparently if the solution treatment is conducted at the temperature 950°~1050°C. However, when the solution treatment temperature is 1100°C, the growth of austenite grain is accelerated. When the solution treatment temperature is over 1150°C, the grain boundaries become straight and more twins are found. As the temperature is elevated, dislocation density is reduced which results in faster grain boundary migration and faster growth of grain size.

Intergranular Corrosion Test and Hardness Test

The intergranular corrosion test shall be conducted on each Incone 600 test piece after the solution treatment in accordance with ASTM G28 Method A. Hardness tests are also carried out to get its Vickers Hardness. The test results are shown in below table:

Specimen
Number
Solution Temp.
°C
Corrosion Rate
mm per year
Hardness
HV10
1 950 0.43 177
2 1000 0.54 180
3 1050 0.63 182
4 1100 0.49 167
5 1150 0.76 139
6 1200 0.36 126

Conclusion: as the solution treatment temperature goes up from 950°C to 1050°C, the hardness of Inconel 600 increased gradually. It achieves maximum at 1050°C and goes down as the solution treatment temperature goes up from 1100°C to 1200°C. The carbides are completely dissolved while the temperature goes up to 1100°C which results in improved resistance to intergranular corrosion. In conclusion, the optimum solution treatment temperature for Inconel 600 shall be 1050°C ~ 1100°C.

ASTM B168 Inconel 600 Plate, Sheet & Strip

As a typical Ni-Cr-Fe alloy, Inconel 600 can be furnished as plates, sheets, or strips which shall be manufactured in accordance with ASTM B168 Gr. N06600.

astm b168 uns n06600 plate 25mm thk inconel 600 - Nickel-based super alloy: Inconel 600 (UNS N06600)

ASTM B168 Gr. N06600 Inconel 600 plate, 1240 mm x 800 mm, thickness = 30 mm

Delivery Conditions and Finishes

Plates, sheets and strips of ASTM B168 UNS N06600 may be furnished in the following conditions & surface finishes:

  • Inconel 600 hot-rolled plate: annealed; or as-rolled.
  • Inconel 600 hot-rolled sheet: annealed.
  • Inconel 600 cold-rolled sheet: annealed; or hard.
  • Inconel 600 cold-rolled strip: annealed; skin-hard; quarter-hard; half-hard; or three-quarter-hard; hard; or spring.

Chemical Requirements

Ni Cr Fe Mn C Cu Si S
≥72.0 14.0-17.0 6.0-10.0 ≤1.0 ≤0.15 ≤0.50 ≤0.50 ≤0.015
  • *Unit: %; The  chemical analysis shall be conducted in accordance with ASTM B880.

Mechnical Properties

Condition Tensile Strength,
min., ksi [MPa]
Yield Strength,
min., ksi [MPa]
Elongation min.,
in 50 mm, %
*A 80 [550] 35 [240] 30
*B 125 [860] 90 [620] 2
  • *A refers to Inconel 600 plate, sheet, strip furnished in annealed condition.
  • *B refers to Inconel 600 materials furnished in hard condition.
  • *The hardness of Inconel 600 shall be tested and specified.

Test Methods for Inconel 600 Plates

The chemical composition, mechanical and other properties of the Inconel 600 plate shall be determined in accordance with the following methods:

  • Chemical analysis: ASTM E38, ASTM E1473
  • Tension requirements: ASTM E8
  • Brinell hardness: ASTM E10
  • Rockwell hardness: ASTM E18
  • Hardness convention: ASTM E140
  • Grain size: ASTM E112
  • Rounding procedure: ASTM E29
  • Spring back: ASTM F155

These test methods are not only applicable to Inconel 600 but also applicable to other nickel-chromium-iron alloys and nickel-chromium-cobalt-molybdenum alloys plates, sheets, and strips. The alloys include ASTM B168 UNS N06601(Inconel 601), N06603(Inconel 603), N06690(Inconel 690), N06693(Inconel 693), N06025, N06045, N06617(Inconel 617).

Manufacturing Process of Inconel 600 Plates (ASTM B168 Gr. N06600)

Recently, we have supplied approximate 26 metric tonnes of Inconel 600 plates to a HFC-134a project in Brazil. The plates are manufactured to ASTM B168 Grade N06600 specification mainly used for the construction of pressure vessels and reactors. First, the Φ240 electrode bars were made in non-vacuum induction melting furnace(Non-VIM) which were remelted to Inconel 600 Φ360 bars through electroslag remelting process. The products were bloomed to billets sized of 105 mm x 240 mm and 105 mm x 290 mm by using cogging hammer. And they were preliminary rolled to billets sized (19.5~50.5)mm x (260~290)mm and (62~87)mm x (260~290)mm, which were subsequently fed to the Three-High Lauth Plate Mill for precision rolling.

inconel 600 production flow chart 01 - Nickel-based super alloy: Inconel 600 (UNS N06600)

Inconel 600 plate production flow chart 01: melting and remelting.

inconel 600 production flow chart 02 - Nickel-based super alloy: Inconel 600 (UNS N06600)

The production flow chart of Inconel 600 plates 02: rough rolling and precision rolling.

Specifically, the following procedures for precision rolling of Inconel 600 plates include: billets examination → hot rolling → annealing → pickling → grinding & cleaning → cold rolling → annealing → pickling → leveling → flattening → cutting → ultrasonic test → final inspection → marking → packaging → storing.

  • The completed products are Inconel 600 sheets of 2 m x 1 m x 2.5 mm and Inconel 600 plates of 2 m x 1.2 m x 6.5 mm;
  • standard: ASTM B168 Gr. N06600.
  • The hot rough rolling & blooming temperature: 1120°C ± 10°C;
  • Hot precision rolling temperature: 1090°C ± 10°C;
  • Hot rolling maximum deformation rate of each pass: 30%; 
  • Cold rolling total deformation rate: 30% ~ 40%; 
  • Annealing temperature for hot-rolled plates: 1000~1020°C; 
  • Annealing temperature for cold-rolled plates: 980~1000°C;
  • Both are air cooling.

Inconel 600 Plates for HFC-134a Reactors

HFC-134a is an excellent environment-friendly coolant that is widely used as the substitute of Freon. The HFC-134a reactors are the core equipment in the production process. Generally, the medium that flows through the tube side of the reactor include HF, HCl, Fluorohydrocarbon, and little amount of water, while the reacting temperature is at 350°C ~ 370°C. Inconel 600 plates (ASME SB-168 UNS N06600) are selected as the main internal material of tube side. Inconel 600 has excellent resistance to oxidation and carbonization at high temperatures. It has good resistance to dehydrated chlorine at medium temperature and considerable immunity to stress corrosion cracking induced by chloride ion.

a hfc 134a reactor with inconel 600 plates internal cladding - Nickel-based super alloy: Inconel 600 (UNS N06600)

An HFC-134a reactor for a 3000 MT (annual) capacity project. The internal wall of its tube side is made of Inconel 600 cladding plate.

The vertical type tubular fixed bed reactor for a 3000 t/a HFC-134a project in Poland: diameter: 3600 mm; heating surface: 3600 m2; shell side design pressure: 0.2 MPa; shell side working pressure: 0.15 MPa, shell side design & working temperature: 380°C and 350~380°C; tube side design and working pressure: 1.6 MPa, 1.2 MPa; tube side design and working temperature: 350~380°C; shell side material: ASME SB-515 Gr.65 plates; tube side material: ASME SB-515 Gr. 65 plates cladding with ASME SB-168 Gr. N06600 plates. Heat exchanger tubes: ASME SB-167 Gr. N06600. All Inconel 600 materials shall be solution annealed.

Source: China Inconel 600 Flanges Manufcturer – Yaang Pipe Industry (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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Summary
nickel based super alloy incoloy 800 uns n08800 w nr 1 4876 - Nickel-based super alloy: Inconel 600 (UNS N06600)
Article Name
Nickel-based super alloy: Inconel 600 (UNS N06600)
Description
Nickel-based super alloy: Inconel 600 (UNS N06600) is an early developed nickel-chromium-iron-based solid solution Reinforced alloy, has good high temperature corrosion resistance and oxidation resistance, excellent cold and hot processing and welding process performance, and has satisfactory thermal strength and high plasticity below 700 ℃.
Author
Publisher Name
www.steeljrv.com
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