Why do we think titanium alloy flange is difficult to process?

What is a titanium flange?

Titanium flange is a kind of component made of titanium or titanium alloy, which is connected to the pipe end. It can be made by casting, or by screw connection and welding. The flange connection consists of a pair of flanges, a gasket and a number of bolts and nuts. The gasket is placed between the two flange sealing surfaces. After the nuts are tightened, the specific pressure on the gasket surface reaches a certain value, and the deformation occurs, and the uneven parts on the sealing surface are filled, so that the connection is tight without leakage.


Common brands: TA0, TA1, TA2 , TA3, ta9, TA10, TC4, etc. Flange can be divided into plate flat welding titanium flange, neck butt welding titanium flange, neck flat welding titanium flange, socket welding titanium flange, threaded titanium flange, titanium flange cover (titanium blind plate), etc. according to the pipeline connection requirements.

Titanium flange type / titanium flange connection type:

20191201121435 88759 - Why do we think titanium alloy flange is difficult to process?

Standard for common dimensions of titanium flange:

  • National standard (GB / t9119, Hg / t20592 JB / T Series)
  • Ship mark (gb568-65, gb569-65, gb2503-89, gb2506-89, GB / t10745-89, gb2501-89, gb2502-89)
  • American Standard (ANSI B16.5, ANSI b16.47)
  • German standard (DIN Series)
  • Japanese standard (JIS Series)
  • European standard (en1092-1)
  • Titanium flange material performance standard
  • GB / t16598-2013, GB / t25137-2010, ASTM b381

Physical properties and application scope of common pure titanium / titanium alloy flange:

  • TA1 titanium flange: acid and alkali resistant, high temperature resistant, corrosion-resistant, good ductility, suitable for corrosive, atmospheric pressure pipe connection.
  • TA2 titanium flange: acid and alkali resistant, high temperature resistant, high pressure resistant, suitable for pipe connection with strong corrosion and pressure.
  • Ta9 titanium alloy flange: high temperature resistance, acid and alkali resistance, high pressure resistance, corrosion resistance, suitable for various extreme environments.
  • TA10 titanium alloy flange: acid and alkali resistant, high temperature resistant, high pressure resistant, corrosion resistant, especially suitable for pipe connection with strong acid and alkali environment and strong pressure.

Why do we think titanium alloy flange is difficult to process?

Because of the lack of deep understanding of its processing mechanism and phenomenon.

1. Physical phenomenon of titanium processing
The cutting force of titanium alloy flange is only slightly higher than that of steel flange with the same hardness, but the physical phenomenon of titanium alloy flange machining is much more complex than that of steel flange machining, which makes the titanium alloy flange machining face great difficulties.

Most titanium alloy flanges have very low thermal conductivity, only 1 / 7 of steel flange and 1 / 16 of aluminum flange. Therefore, the heat generated in the process of cutting titanium alloy flange will not be transferred to the workpiece or taken away by the chips, but gathered in the cutting area, the temperature generated can be as high as 1000 ℃ or above, which makes the cutting edge of the tool wear, crack and generate chip accretion rapidly, the worn cutting edge appears rapidly, and more heat is generated in the cutting area, further shortening the service life of the tool.

The high temperature produced in the cutting process destroys the surface integrity of the titanium alloy flange parts at the same time, which leads to the decline of the geometric accuracy of the parts and the phenomenon of work hardening that seriously reduces its fatigue strength.
The elasticity of titanium alloy flange may be beneficial to the performance of flange, but in the process of cutting, the elastic deformation of flange is an important reason for vibration. The cutting pressure makes the “elastic” flange leave the tool and rebound, so that the friction between the tool and the workpiece is greater than the cutting effect. The friction process also produces heat, which aggravates the problem of poor thermal conductivity of titanium alloy flange.
When machining thin-walled or ring shaped parts, this problem is more serious. It is not easy to process titanium alloy thin-walled parts to the expected dimensional accuracy. Because when the workpiece material is pushed away by the cutter, the local deformation of the thin wall has exceeded the elastic range, resulting in plastic deformation, and the material strength and hardness of the cutting point increase significantly. At this time, according to the originally determined cutting speed, the machining becomes too high, which further leads to sharp tool wear.
“Heat” is the “culprit” of titanium alloy flange difficult to process!
2. Know how to process titanium alloy flange
On the basis of understanding the processing mechanism of titanium alloy flange and previous experience, the main know-how of processing titanium alloy flange is as follows:

  • (1) the blade with positive angle geometry is used to reduce cutting force, cutting heat and workpiece deformation.
  • (2) keep constant feeding to avoid hardening of the workpiece. During the cutting process, the tool should always be in the feeding state. During the milling, the radial cut a e should be 30% of the radius.
  • (3) adopt high-pressure and large flow cutting fluid to ensure the thermal stability of the processing process, and prevent the workpiece surface denaturation and tool damage due to the high temperature.
  • (4) keep the blade edge sharp and blunt tool is the cause of heat accumulation and wear, which is easy to lead to tool failure.
  • (5) it should be processed in the softest condition of titanium alloy flange as much as possible, because the material becomes more difficult to process after hardening, heat treatment improves the strength of material and increases the wear of blade.
  • (6) use a large tip arc radius or chamfer to cut in, and try to put more blades into cutting. This can reduce the cutting force and heat at each point and prevent local damage. In the milling of titanium alloy flange, the cutting speed has the greatest influence on the tool life VC, followed by the radial cut (milling depth) AE.

3. Solve the problem of titanium processing from blade
The wear of blade groove in titanium alloy flange machining is the local wear of the back and front along the cutting depth direction, which is often caused by the hardening layer left by the previous machining. The chemical reaction and diffusion of cutting tool and workpiece material at the processing temperature over 800 ℃ is also one of the reasons for the formation of groove wear. Because in the process of machining, titanium molecules of the workpiece accumulate in front of the blade, and “weld” to the blade under high pressure and high temperature, forming chip accretion tumor. When the chips are peeled off from the blade, the carbide coating of the blade will be taken away. Therefore, titanium alloy flange processing needs special blade material and geometry.
4. Cutter structure suitable for titanium flange machining
The focus of titanium alloy flange machining is heat. A large amount of high-pressure cutting fluid should be sprayed on the cutting edge timely and accurately to remove the heat quickly. There is a unique structure of milling cutter specially used for titanium alloy flange processing on the market.

Source: China Titanium Alloy Flange Manufacturer – 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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