Other nickle-base alloys

Inconel 600 Alloy

Inconel 600 alloy is a kind of Ni Cr alloy, which can be used in the temperature range from low temperature to 1093 ℃. Inconel 600 alloy has no magnetism and good welding performance.


Inconel 600 alloy can be used in a wide range of corrosion environments. High nickel content makes alloy 600 have a certain corrosion resistance to reducing environment, while the addition of chromium makes alloy 600 have a certain corrosion resistance to weak oxidizing environment. Because of the high content of nickel, alloy 600 has excellent corrosion resistance to chloride stress corrosion cracking.
The formability of alloy 600 is similar to that of stable austenitic stainless steel.

Chemical composition of Inconel 600

The chemical composition of alloy 600 is shown in the table below.

Element

wt%

C

0.05

Mn

0.25

S

0.002

Si

0.20

Cr

15.5

Ni+Co

Allowance

Fe

8.0

Cu

0.10

Product form and standard

The main products of alloy 600 are plate and strip. The supply state is mainly annealing state, sheet and strip can also be supplied in normalizing state. The following table shows some international standards for alloy 600.

Product form

Standard

 

ASTM

ASME

AMS

Plate and strip

B168

SB168

5540

Pipe and fittings

B167

SB167

5580

 

B516

SB516

 

 

B517

SB517

 

Condenser tube

B163

SB163

 

Rods and forgings

B166

SB166

5665

 

B564

SB564

 

Wire

B166

SB166

5687

Corrosion resistance and application of alloy 600

The high nickel content of alloy 600 makes it have good corrosion resistance to medium strength reducing environment and chloride ion stress corrosion cracking. Therefore, alloy 600 can be used in MgCl2 solution.
Similarly, chromium makes alloy 600 have certain corrosion resistance in weak oxidizing environment. In a sense, alloy 600 has become a substitute for commercial pure nickel. But the corrosion resistance of alloy 600 is poor in the strong oxidizing solution like hot concentrated nitric acid.
Alloy 600 will not corrode in neutral and alkaline salt solution, so it can be used in severe corrosion environment.
Alloy 600 is resistant to the mixture of steam, air and carbon oxides, but it will corrode in high temperature gas containing sulfur.
Alloy 600 has excellent resistance to carbonization and oxidation at high temperature, so it has been used in heat treatment industry for a long time. It has good resistance to dehydrated Cl2 and HCl gas at medium high temperature. Alloy 600 is resistant to stress corrosion in the process of alkali concentration.
In summary, alloy 600 has the following characteristics:

  1. It is still antioxidant until 1093 ℃;
  2. Carbonation resistance;
  3. It is still resistant to dehydrated Cl2 at about 538 ℃;
  4. It is immune to chloride stress corrosion cracking;
  5. It has good resistance to alkali corrosion.

Its applications are as follows:

  1. Heat treatment related components and equipment;
  2. Chlorination equipment with temperature up to 538 ℃;
  3. Alkali dissolving tank of pulp mill;
  4. Equipment related to alkali concentration.

Physical properties of alloy 600

Density: 8.42g/cm3
Specific heat: (0-100 ℃) 460j / kg-k
Permeability: < 1.02
The following table is the linear thermal expansion coefficient data of alloy 600
Coefficient of linear thermal expansion

21-T

Coefficient  10-6/

93

12.4

204

13.1

316

13.7

427

14.2

538

14.6

649

15.1

760

15.7

Table is the data of heat conductivity of alloy 600
Thermal conductivity

Temperature 

Thermal conductivity W/m-k

21

14.8

93

15.4

204

17.1

316

18.7

427

20.6

538

22.5

mechanical property of alloy 600
The mechanical properties of annealed state at room temperature are shown in the table below.

0.2% yield strength(MPa)

Tensile strength(MPa)

Elongation rateδ5(%)

255

640

45

The table shows the short-term high-temperature tensile property data of alloy 600. The properties at low temperature are added for comparison.

Test temperature ℃

0.2% yield strength(MPa)

Tensile strength(MPa)

Elongation rateδ5(%)

-79

292

734

64

316

213

624

46

427

203

610

49

538

197

579

47

649

183

448

39

760

117

190

46

871

62

103

80

982

28

53

118

Impact properties of alloy 600

Alloy 600 has good toughness even below zero. The following table shows the impact performance data of V-groove of alloy 600.

Test temperature           ℃

Impact strengthJ

 

Annealing

Hot-rolling

Cold rolling

-73

244

244

21

244

244

156

538

217

217

Processing and heat treatment of alloy 600

Cold forming

The cold formability of alloy 600 is very good. The transformation from austenite to martensite can be prevented by high nickel content during cold working, and such transformation will occur in 301 and 304 stainless steels during cold working. The work hardening tendency of alloy 600 is lower than that of stainless steel 301 and 304, and large-scale deformation operation of alloy 600 can be carried out by various processing methods.
High temperature annealing of alloy 600 will make its grains grow. A large range of forming operations will cause the appearance of wavy “orange peel” on the alloy surface, mainly because of its large grain size, but this phenomenon does not harm the performance of the material.

Heat treatment

Alloy 600 will not harden due to heat treatment, only cold work strengthening.
Annealing after cold working can soften the material. The softening temperature can be between 871 ℃ and 1149 ℃. At 982 ℃ or higher, grain growth is very rapid, but a short stay at 1038 ℃ can soften the material without improper grain growth.
The cooling after heat treatment can be slow cooling or rapid quenching cooling, and the hardness will be considerable.

Welding

Standard resistance welding and fusion welding can be used for alloy 600. Now there are a large number of electrodes and welding wires can be used to weld alloy 600. Close oxide will be produced near the weld of alloy 600, which can only be removed by grinding. In addition, inert gas welding is preferred.

Incoloy 800 Alloy

800 alloy is a kind of Ni Fe Cr alloy used to resist oxidation and carbonization. The content of nickel is 32%, which makes 800 alloy have good resistance to chloride induced stress corrosion fracture and σ phase precipitation. Alloy 800 has excellent resistance to uniform corrosion. In solution treated condition, 800H and 800at have excellent creep and stress fracture properties. The three kinds of alloy based on 800 alloy have passed the review of ASME Boiler and pressure vessel material specification, which has application standards for 800 series alloy in the first part – power plant boiler, the third part – nuclear vessel and the eighth part: non direct contact fire pressure vessel.
800 series alloy is basically the same, except for the slightly higher carbon content (0.05-0.10%) in 800H, 1.00% Al + Ti is added in 800at. 800 alloy can be used to 593 ℃. 800H and 800at are generally used at temperatures above 593 ℃, which are very demanding for creep and stress corrosion cracking.

Chemical composition of incoloy 800

The typical chemical composition of 800 series alloy is shown in the table below.

Element

800

800H

800AT

C

0.02

0.08

0.08

Mn

1.00

1.00

1.00

P

0.020

0.020

0.020

S

0.010

0.010

0.010

Si

0.35

0.35

0.35

Cr

21.0

21.0

21.0

Ni

32.0

32.0

32.0

Ti

0.40

0.40

 

Al

0.40

0.40

 

Ti+Al

 

 

1.00

Cu

0.30

0.30

0.30

Material standard of incoloy 800

The following table is the international standard of 800 series alloy.

Product form

Standard

ASTM

ASME

AMS

Plate and strip

B409

SB409

5871

Welded pipe

B514*

 

 

Seamless pipe

B163

SB163

 

B407

SB407

 

Bar

B408

SB408

 

Forging

B564

SB564

 

*For alloy 800 only

Corrosion performance and application of incoloy 800

The nickel content of 800 series alloy is much higher than that of 304 stainless steel family. In many media, 800 series alloy and 304 stainless steel are very similar. For example, in many industrial gases and chemical media such as nitric acid and organic acid, they have considerable performance. No matter 800 series alloy or 304 stainless steel can be used in sulfuric acid environment, except for low temperature and low concentration.
Like austenitic stainless steel, if 800 series alloy is heated for a long time in the range of 538-760 ℃, chromium carbide will precipitate at the grain boundary of the alloy, which will cause sensitization of the alloy and intergranular corrosion of the alloy in the environment like pickling and 65% nitric acid.
Although 800 series alloy has no immunity to chloride ion stress corrosion cracking, its corrosion resistance is very good. It has good corrosion resistance in petroleum, chemical industry, food, pulp and paper industry. Obviously, 800 series alloy can be used in the medium corrosion environment which can make the stress corrosion fracture of ordinary austenitic stainless steel. However, 800 series alloys have no immunity to stress corrosion cracking of MgCl2 solution.
The most typical application of alloy 800 is at high temperature, such as incinerator elements, petrochemical reforming unit, hydrocracking pipe fittings, superheated steam treatment equipment of conventional power plants and nuclear power plants. High content of chromium and nickel makes 800 series alloy have good resistance to oxidation and carbonization.
The 800 series has the following characteristics:

  • According to ASME standard, it has high design strength when applied at 899 ℃;
  • The tube can be used at a temperature below 982 ℃;
  • At 1038 ℃, it still has oxidation resistance;
  • Resistant to chloride ion corrosion.

Mechanical property of incoloy 800

The typical room temperature mechanical properties of 800 series alloy are shown in the table below. Among them, 800 alloy is annealed at 982 ℃, 800H and 800at alloy are annealed at 1149 ℃, the different annealing temperature is mainly due to the different strength of the material.

Test temperature  ()

0.2% yield strength(MPa)

Tensile strength(MPa)

Elongation rateδ5   (%)

21

295

600

44

93

274

563

43

260

234

525

39

427

230

514

40

538

219

496

39

649

200

372

56

760

156

221

85

816

98

171

91

Mechanical properties of 800H and 800AT

Test temperature  ()

0.2% yield strength(MPa)

Tensile strength(MPa)

Elongation rateδ5   (%)

21

200

531

52

93

166

490

53

316

131

459

53

427

125

454

53

538

114

438

51

649

102

384

50

760

99

223

78

871

80

128

120

982

61

70

120

Processing and heat treatment of incoloy 800

Cold forming
800 series alloy shows excellent formability. High nickel content prevents transformation from austenite to martensite, which may occur during cold working of 301 and 304 stainless steel. Large scale forming operation will cause ripple like “orange peel” phenomenon on the alloy surface, mainly due to its large grain size, but this phenomenon has no harm to the material performance.
Heat treatment
The annealing treatment of 800 alloy is generally between 982-1038 ℃, the main purpose is to refine the grains.
The heat treatment temperature of 800H and 800AT is generally between 1121-1177 ℃. In addition to the purpose of softening the material, it is also to make the grains grow up and improve the creep resistance and stress fracture performance of the material.
Welding
800 series alloy can be welded by GTAW or MIG.
Now there are a large number of electrodes and welding wires that can be used to weld 800 alloy. Close oxide will be produced near the weld of alloy 800, which can only be removed by grinding. In addition, inert gas welding is preferred.

Monel 400

Monel 400 is a single-phase solid solution Ni Cu alloy, which has good corrosion resistance in many media. From mild oxidizing medium environment to neutral environment, to suitable reducing environment, it has good corrosion resistance. This alloy has a long history as a corrosion-resistant material. In the early 20th century, people tried to use nickel ore with high content of copper to smelt alloys. Today, the proportion of nickel and copper in Monel 400 is similar to the original ore.
Like commercial pure nickel, Monel 400 has low strength in annealed state. For this reason, tempering is often required to improve its strength.

  • Its characteristics can be summarized as follows:
  • It has good corrosion resistance in marine and chemical environment;
  • It is not sensitive to chloride stress corrosion cracking;
  • It has good mechanical properties from below zero to 550 ℃;
  • Approved by ASME, it can be used as pressure vessel at – 10 ~ 425 ℃;
  • Good processing and welding performance.

Chemical composition of monel 400

Element

Ni

Fe

C

Mn

Si

Cu

Al

S

Minimum

63.0

1.0

 

 

 

28.0

 

 

Maximum

 

2.5

0.15

1.25

0.5

34.0

0.5

0.02

Material standard of monel 400

Product form

Standard

ASTM

ASME

AMS

Plate and strip

B127

SB127

4544

 

 

 

Seamless pipe

B163

SB163

4574

B165

SB165

 

Bars and forgings

B164

SB164

4675

B564

SB564

 

Wire

 

 

4730

 

 

4731

  • ASTM: American Society for testing and materials standard;
  • ASME: American Society of mechanical engineers standard;
  • AMS: American military standard

Physical property of monel 400

Density: 8.8g/cm3

Melting range: 1300 ~ 1350 ℃

Temperature        ℃

Specific heat     (J/kg-k

Thermal conductivity(W/m-k

Resistivity      (μΩcm

Modulus of elasticity   (Gpa

Coefficient of thermal expansion  (20~T) 10-6/k

-130

 

22

 

 

11.5

-75

 

24

 

 

12.1

20

430

26

51.3

182

 

100

445

29.5

54

180

13.9

200

465

33

55.5

177

15.5

300

478

36.5

57.5

170

15.8

400

490

40

58.5

165

16.0

500

 

44

60

150

16.3

600

 

48.5

61.8

 

16.6

700

 

52

63.5

 

17.0

800

 

56

65.5

 

17.4

900

 

58

67.5

 

17.5

Performance and Application of monel 400

Monel 400 has excellent corrosion resistance to neutral environment, alkali and salt environment.
This kind of alloy material is a rare kind of metal that can resist fluorine, hydrofluoric acid, hydrogen fluoride or their derivatives. It is also very corrosion-resistant in caustic soda. It has similar cavitation corrosion resistance to copper base alloy in seawater environment. In sulfuric acid, hydrochloric acid and other environments, especially in the absence of air, the effect is better. However, due to the absence of Cr in the material, the corrosion rate will be greatly increased in the oxidizing environment.
Although Monel 400 has good resistance to chloride ion stress corrosion cracking, it will produce stress corrosion cracking in the environment with mercury or hydrogen fluoride gas exposed to humidity. At this time, it is necessary to pay attention to the stress relief heat treatment of the material.
Typical engineering applications are as follows:

  • 1. Water supply and steam generator piping system of the power station;
  • 2. Theme of heater and evaporator in salt plant;
  • 3. Alkylation unit of sulfuric acid and hydrofluoric acid;
  • 4. Industrial heat exchanger;
  • 5. Composite plate in crude distillation unit;
  • 6. Wave guards for offshore installations;
  • 7. Shaft of propeller and pump in sea water system;
  • 8. Uranium and isotope separation system in nuclear fuel production;
  • 9. Pumps and valves in the production of hydrocarbon chlorination;
  • 10. Mea reboiler piping.

Academic performance of monel 400

Minimum mechanical properties at room temperature

State

Standard

Tensile strengthMPa

0.2% yield strengthMpa

1.0% yield strengthMPa

Elongation rateδ5 %

Brinell hardness (HB

Annealing

DIN

450

180

210

35

150

ASTM ASME BS

480

195

220*

35

 

Stress relieving

DIN

550

300

 

25

~170

VdTüV-Wbl

580

400

 

18

 

ASTM ASME BS

550~600

275~415

 

20

 

Sclerosis

DIN

700

650

 

3

~210

ASTM ASME

690~760

620

 

2

 

* Only specified in British national standard

Minimum mechanical properties in German national standard VdTüV-Wbl

Annealing condition

Minimum 0.2% yield strength

Tensile strength

Temperature℃

100

200

300

400

425

100

200

300

400

425

MPa

150

135

130

130

130

420

390

380

370

360

ISO standard V-notch impact strength: (average)
Annealing state ≥ 150j / cm2
Stress relief state ≥ 100J / cm2
ISO standard V-notch impact strength: (average)
Annealing state ≥ 150j / cm2
Stress relief state ≥ 100J / cm2

Manufacturing and heat treatment of monel 400

Monel 400 can be easily manufactured by traditional process.
Heating
It is very important to ensure that the Monel 400 surface is clean before heat treatment.
If there are contaminants such as s, P, Pb or other low melting point metals on the surface of Monel 400 during heating, the properties of the alloy may be weakened. The main sources of pollutants are marker marks, temperature indicating paint, lubricating grease and furnace gas. The sulfur content of furnace gas must be low.
The furnace gas shall be neutral or slightly reductive, and shall not fluctuate between reducibility and oxidizability. The flame in the furnace shall not directly impact the material.
Hot working
Monel 400 can be hot worked in the range of 800-1200 ℃, but only slightly forged under 925 ℃. Hot bending can be carried out at 1025-1200 ℃. In order to carry out the heat treatment, the furnace temperature should be heated to 1200 ℃, and then the Monel 400 material should be put into the furnace for heating.
The material shall be heated according to a rule: heat for 60 minutes every 100 mm thick. As soon as the heating time is up, the material shall be taken out for hot processing. If the material temperature drops below the minimum hot processing temperature during the hot processing, it shall be reheated.
Cold working
The cold worked Monel 400 material must be annealed. Because it has a slightly higher work hardening rate than carbon steel, the forming equipment should be changed appropriately. Annealing treatment between processes is needed for cold forming.
Cold deformation is sometimes used to improve mechanical properties. If the material is to be used in an environment prone to stress corrosion cracking, such as mercury, hydrogen fluoride gas exposed in humidity, etc., it is recommended to conduct stress relief heat treatment.
Heat treatment
The annealing temperature of Monel 400 is generally 700 ~ 900 ℃, and 825 ℃ is the best. Good corrosion resistance can be obtained by rapid air cooling after treatment.
Annealing temperature and time are directly related to the final grain size of the material, so annealing parameters should be considered carefully.
And the sulfur content of the gas in the annealing furnace must be low to avoid embrittlement of the material. The stress relief heat treatment is usually carried out at a low temperature of 300 ℃ for 1-3 hours.
For pipes, the temperature of stress relief heat treatment is generally controlled between 550 ℃ and 650 ℃.
Before any heat treatment, the cleaning of material surface must be taken seriously.
Scale removal
The oxide and stain near the weld of Monel 400 material are closer than that of stainless steel material. Before pickling in the mixed acid of nitric acid and hydrofluoric acid, it can be grinded with grinding wheel or pretreated in salt bath.
Machining
Monel 400 material should be machined in annealed condition. After cold forming and stress relief, the material is easier to be machined, so the work hardening of this kind of material should be fully understood. For example, the surface cutting speed is smaller than that of carbon steel, the cutter should be operated continuously, and the feed amount should be large to avoid the surface hardening layer.
Machining tools shall be special tools for nickel base alloy and high alloy stainless steel, and stainless steel brush shall be used for welding seam. Manufacturing and processing machinery, such as plate shears, presses, rolling machines, etc., should take measures to avoid pollution by iron impurities. The processing site shall be clean and separated from the carbon steel processing site.
Welding
The welding groove of Monel 400 material is suitable to be finished by machining. If the groove is polished, local overheating shall be avoided. Because nickel alloy and high alloy stainless steel have obvious physical properties difference compared with carbon steel, their heat conductivity coefficient is low, and the coefficient of thermal expansion is large. For this point of welding, we need to use clamping, large welding feet (1-3mm) and other methods to solve. Because of the poor fluidity of molten metal in Monel 400 material welding, a large groove angle (60-70 °) should be adopted to make the welding wire can fill the weld. The groove and electrode shall be cleaned with acetone before welding, GTAW shall be used for welding, ernicu-7.monel 400 shall not be preheated before welding, and post weld heat treatment is generally not required, because the material strength after processing has been improved, which is beneficial for future use. Common welding groove forms are shown in the figure.

20200321172017 90144 - Other nickle-base alloys

Tantalum

Tantalum has excellent corrosion resistance in most inorganic acids and is very similar to glass. It has an important use in chemical industry. Besides hydrofluoric acid, fluorine, fuming sulfuric acid and alkali, tantalum can almost resist the corrosion of all chemical media (including hydrochloric acid, nitric acid at boiling point and sulfuric acid below 175 ℃).
Tantalum has excellent corrosion resistance to dilute sulfuric acid less than 75%, and can be used at any temperature; for non aerated concentrated sulfuric acid, it can be used at 160-170 ℃; for aerated concentrated sulfuric acid, it can be used at 250-260 ℃, and the corrosion will increase when the temperature exceeds this value. Generally, it is necessary to carry out experimental research before using at high temperature above 170 ℃. Tantalum also has good corrosion resistance to phosphoric acid, but if the acid contains a small amount of fluorine (> 4ppm), the corrosion rate will increase.
Tantalum is usually not corrosion-resistant in alkali, it will become brittle and corrode faster under high temperature and high concentration.
Tantalum can react with high temperature gas (except inert gas), and O2, N2, H2, etc. can penetrate into the interior to make it brittle. If contacting with primary h, it will also absorb hydrogen to become brittle. Therefore, tantalum equipment can not contact with more active metals (such as Fe, Al, Zn), because it is easy to form tantalum iron (al, Zn) primary battery, and the hydrogen generated by the reaction of primary battery will destroy the tantalum cathode, making the equipment invalid. If a small piece of platinum (about one thousandth of tantalum) with very small hydrogen overvoltage is used to connect with tantalum, then all hydrogen will be released on the platinum, which can avoid the damage of hydrogen to tantalum.
Tantalum has excellent corrosion resistance, but its price is expensive, so its application forms are mainly composite plate and lining, In order to reduce the cost, the thickness of tantalum layer is expected to be as thin as possible, so the welding of composite plate or lining is very difficult, because the melting point of tantalum material and steel is very different (the melting point of tantalum material is 2996 ℃, the melting point of steel is 1400 ℃), and Fe and TA will form fe2ta brittle intermetallic compound at high temperature, if the measures are not appropriate, it is easy to cause weld cracking.
In the welding of thin-layer tantalum steel composite plate or lining, the thickness of the composite layer has an important influence on its weldability. Figure 1 is the welding diagram of TA1 / 16MnR composite plate. The smaller the thickness of the composite layer is, the higher the temperature T on the composite interface is. When t > 1500 ℃, there will be a melting zone of 16MnR on the interface. When Fe and Ta are at 1460 ℃, eutectic reaction will take place, resulting in Fe2Ta brittle intermetallic compound. Under the effect of welding stress, it is easy to produce cracks, and one side of tantalum on the interface will expand to the tantalum weld pool. In serious cases, penetrating cracks will be produced. At this time, the melted iron on the base layer will pass through the penetrating cracks and diffuse to the tantalum weld pool, and react with tantalum to generate Fe2 TA brittle compound to crack the weld.

20200321173221 88279 - Other nickle-base alloys

Figure.1 TA1 / 16MnR composite plate welding diagram

In order to prevent this phenomenon, the first factor is to appropriately increase the thickness of the cladding or take other measures to reduce the interface temperature. For example, in order to transfer the heat generated during welding to the surrounding, a layer of other metals with rapid heat conduction is pre compounded at the interface. A model of the relationship between the interface temperature ts and the clad thickness h can be established through a lot of experiments. As shown in Figure 2.

20200321173614 14996 - Other nickle-base alloys

Figure.2 Relationship between interface temperature and clad thickness

When h ≤ 2.0mm, the interface steel melts, the iron diffuses into the weld, and the weld cracks. When h > 2.0mm, the welding of TA steel composite plate can be realized, and the greater the thickness of cladding, the better the weldability. Generally, 2.5-4.0mm is suitable for the thickness of composite layer. When it is used as lining, 0.3 ~ 0.5mm can be used.

Zirconium

Zirconium is an active metal, which is easy to produce oxidation reaction. For example, it can react with oxygen in the air at room temperature to form an oxide protective film. This protective film gives zirconium and zirconium alloys the best corrosion resistance. The oxide film can be further strengthened by heat treatment. The microhardness of the surface can be approximately 480 (Rockwell c-scale 47). As a good bearing surface, it can resist the corrosion of all kinds of media, bring strong wear resistance to high-speed system equipment, and also bring strong corrosion resistance to some high-corrosion environment. Zirconium has good corrosion resistance to reductive environment and to most acids. Among them, it has good corrosion resistance to less than 10% boiling sulfuric acid. It can be applied to 100 ℃ for 10-40% sulfuric acid, 60 ℃ for 50-60% sulfuric acid, and 35 ℃ for 70-80% sulfuric acid. It only corrodes seriously in hydrofluoric acid, concentrated sulfuric acid, aqua regia and other media. It also has good corrosion resistance to oxidizing environment such as nitric acid and chromic acid, but if it contains chloride (such as FeCl3 and CuCl2), the corrosion will increase sharply. In the environment containing Fe3 + and Cu2 +, there will be cavitation. It has good corrosion resistance to alkali, molten alkali and salt solution, but it is not resistant to wet chlorine. In chemical industry, it is mainly used in hydrochloric acid, molten alkali, acetic acid and other industries.
The following table shows the corrosion data of zirconium in chemical process such as acetic acid.

Corrosion performance table of zirconium

Medium

Concentration,%

Temperature,℃

Time,h

Corrosion rate,mm/a

Acetic acid

5

100

144

0

 

25

100

144

0

 

50

100

144

0.0007

 

75

100

144

0

 

99.5(无水)

Boiling

144

0

Acetic anhydride 65.43% + acetic acid 34.3% + benzene 0.27%

 

Boiling

144

0.0015

Chloroacetic acid

100

100

144

0

Two chloroacetic acid

100

100

144

0.214

Three chloroacetic acid

100

100

144

11.6

Zirconium alloy has good ductility even at low temperature and similar strength to other engineering alloys. Oxygen is not only an indispensable component of oxide film, but also an alloy element for zirconium alloy to fill the structural gap and increase its strength. Zirconium alloy has no tendency from plasticity to embrittlement at low temperature.

Chemical composition of zirconium

The total content of zirconium and hafnium is 95.5% to 99.2%. The highest content of hafnium is 4.5%. Non nuclear zirconium alloy can be divided into two grades: Zr702 and zr705. The two grades of materials have excellent corrosion resistance, only slightly different in physical and mechanical properties. Zr702 is a commercial material, while zr705 is an alloy of zirconium and niobium to enhance its strength and improve its die forging performance. The chemical composition of zirconium alloy is listed in Table 1. The change of hafnium content has no great influence on the physical properties, mechanical properties and corrosion resistance of the materials.
Table 1 chemical composition

Level

Zr702

Zr705

Element

Weight%

Weight%

Zirconium + hafnium minimum

99.2

95.5

Hafnium highest

4.5

4.5

Iron + chromium maximum

0.20

0.20

Tin highest

Hydrogen highest

0.005

0.005

Nitrogen highest

0.025

0.025

Carbon highest

0.05

0.05

Niobium

2.0~3.0

Oxygen highest

0.16

0.18

Thermodynamic properties of zirconium

The thermodynamic properties of zirconium and zirconium alloys are shown in the table below.

Project

Zr702

Zr705

Melting point

1852

1840

Specific heat KJ/Kg-K(0-100)

0.2847

0.2805

Vapor pressure mmHg

2000

0.01

 

3600

900

Thermal conductivity W/m-K(300-800K)

22

17.1

Coefficient of thermal expansion 10-6/

38

5.8

3.6

 

149

6.3

4.9

 

260

7.0

5.6

 

371

7.4

5.9

Latent heat of fusion Cal/gm

60.4

Latent heat of evaporation Cal/gm

1550

Mechanical properties of zirconium

Table 1 lists the physical properties of zirconium and its alloys. It can be seen from the table that the elastic modulus of zirconium and zirconium alloy decreases rapidly with the increase of temperature. The specific gravity of zirconium and zirconium alloy is more than 20% lower than that of stainless steel alloy mainly composed of ferronickel.
Figure 1, figure 2 and table 2 show the mechanical properties of typical zirconium and zirconium alloy after annealing. The data in these charts show the average values of longitudinal and transverse performance at different temperatures. The yield strength and elongation data were determined by 0.2% permanent deformation method. Like most non-ferrous metals, zirconium and its alloys gradually change from elasticity to plasticity. Some of its physical and mechanical properties are affected by directivity. These properties, including thermal expansion, yield strength, ultimate tensile strength, elongation, notch toughness and bending plasticity, vary with the direction.
The elongation of two grades of zirconium and zirconium alloy increased obviously with the increase of temperature. This increase in ductility and low yield strength at 204 ° C reduce the technical difficulties in some forming processes.
Table 1 physical properties

Project

Zr702

Zr705

Modulus of elasticity,Gpa

Room temperature

99.2

94.7

 

38

98.6

93.8

 

93

93.1

90.5

 

149

86.9

87.3

 

204

80.7

84.2

 

260

75.2

81.0

 

316

69.9

77.8

 

371

64.1

74.7

Shear modulus of elasticity,Gpa

36.2

34.5

Poisson’s ratio (room temperature)

0.35

0.33

Proportion g/cm3 (20)

6.51

6.64

Table.2 Mechanical properties (cold worked, annealed)

Project

Zr702

Zr705

 

Ultimate tensile strengthMpa

Yield strength   (Mpa

Permanent deformation method with elongation of 0.2%%

Ultimate tensile strengthMpa

Yield strength   (Mpa

Permanent deformation method with elongation of 0.2%%

ASTM minimum value

379

207

16

552

379

16

Room temperature

468.1

321.1

28.9

615.0

506.1

18.8

93

364.0

267.5

31.5

149

303.7

195.8

42.5

388.9

272.3

31.7

204

229.6

139.3

49.0

260

200.6

128.9

49.0

326.1

195.8

28.9

316

197.9

97.2

40.1

371

156.5

82.0

44.1

Heat treatment of zirconium

Annealing
The annealing temperature of cold worked pure zirconium is about 300 ℃. In order to reduce the corrosion and hydrogen absorption rate and stabilize the structure, stress relief annealing is usually carried out after cold working. After stress relief annealing, the strength of Zircaloy changed little, but the plasticity of Zircaloy increased obviously.
Quenching
When zirconium is cooled rapidly, the transformation of shear martensite may occur. Generally speaking, the hardening of zirconium and its alloy in β zone can be achieved to a certain extent. For example, the tensile strength of zirconium bars containing 0.02% C, 0.03% O, 0.135% Al and trace other impurities will increase from 269mpa to 310mpa after quenching at 1000 ℃, and will increase after tempering at 400 ℃.
Quenching aging
It is found that zr705 is a typical alloy strengthened by quenching and aging.
A large number of test results also show that heat treatment specifications have a strong impact on the mechanical properties and corrosion resistance of zr705 alloy, and only through heat treatment and cold processing can we get satisfactory high strength and high corrosion resistance.
The solution treatment temperature of zr705 is usually 880 ℃, holding for 0.5 hours, then quenching, the Vickers hardness value after quenching is 245 ± 5kg / mm2
The aging temperature is usually 500 ℃, the hardness of the alloy increases in the first 3-6 hours, and then remains at the maximum value of 265 ± 7kg / mm2 (Vickers hardness). If aging at the lower 300 ℃ and 400 ℃, the hardness will slowly reach the peak value.
The finished products of zirconium and zirconium alloy harden rapidly. The residual stress can be eliminated by heat treatment at 565 ℃ for half an hour to one hour.

ASME allowable stress

Both grades of zirconium alloy are approved for the manufacture of pressure vessels designed to ASME Boiler and high pressure vessel standards. For zr705 material, stress relief heat treatment is required within 14 days after welding. Table 3 shows the modification of the allowable stress value required by the 1997 revision with the 2001 revision of the safety factor according to the ASME Boiler and high pressure vessel standard, Part II, paragraph D.

Fatigue limit

The fatigue limit of Zircaloy is similar to that of most ferroalloys. However, at room temperature, the ultimate tensile strength of Zircaloy is slightly higher in the transverse direction of rolling direction. This slightly higher strength in the transverse direction is different from that of most ferroalloys. This is due to the different properties of A-phase zirconium with close packed hexagonal structure and A-phase iron with BCC Structure in the orientation. The increase of the transverse strength is more obvious when the stress is higher than the fatigue limit.
Figure 3 shows the S-N strength curves of notched and notched zirconium specimens. The theoretical elastic stress concentration factor KT is 3.5. The strength reduction factor KF, which is defined as the ratio of notchless fatigue strength to notched fatigue strength, is 2.6 at room temperature and 1.6 at 400 ℃. Table 4 lists the fatigue limit data of Zircaloy and zircaloy by non alloying method.

Table 3 ASME allowable stress values (Ksi)

Form level

Flat roller SB551 Zr702   Zr705

Pipe   SB523 Zr702   Zr705

Pipe   SB523 Zr702   Zr705

Forging   SB493 Zr702   Zr705

Bar   SB550 Zr702   Zr705

State

 

Seamless   Seamless

Welding*   Weldin*

 

 

100°F

15.8    22.9

15.8    22.9

13.4    19.4

15.8    22.9

15.8    22.9

200°F

13.7    19.0

12.0    16.6

11.7    16.1

13.7    19.0

12.0    16.6

300°F

11.1     16.2

11.1     16.2

9.5     13.7

11.1     16.2

11.1     16.2

400°F

9.1     14.3

9.1     14.3

7.8     12.1

9.1     14.3

9.1     14.3

500°F

7.7     12.9

7.7     12.9

6.5     11.0

7.7     12.9

7.7     12.9

600°F

6.6     11.9

6.6     11.9

5.6     9.7

6.6     11.9

6.6     11.9

700°F

5.8     11.3

5.8     11.3

4.9     8.7

5.8     11.3

5.8     11.3

*The allowable stress value of welded pipe is based on 85% joint efficiency;

*Filler metal shall not be used in the production of welded pipe.

Table.4 Fatigue limit

Alloy

Fatigue limitpsi

 

No gap

Notched

Non alloy, zirconium by iodization

21000

8000

Zr705 heat treated at 556 ℃ for 4 hours

42000

8000

20200321182535 23491 - Other nickle-base alloys

Fatigue curve

Conversion relationship between Fahrenheit and Celsius:
OF=1.8×OC+32

Source: China Alloy Flanges Manufacturer – Yaang Pipe Industry Co., Limited (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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