Causes of cracking of stainless steel head and anti-cracking technology

Understand the causes of cracking in stainless steel heads and crack prevention technology

304 stainless steel is a versatile stainless steel material with stronger rust resistance than the 200 series stainless steel. High temperature resistance is also good, the general use temperature limit is less than 650 °C. 304 stainless steel has excellent stainless corrosion resistance and good resistance to intergranular corrosion. For oxidizing acids, it is found in the experiment that 304 stainless steel has strong corrosion resistance in nitric acid below the boiling temperature of ≤ 65%. It also has good corrosion resistance to alkaline solutions and most organic and inorganic acids.

It indicates that the leakage of the pipeline is caused by sensitization during welding and rapid cracking along the crystal stress corrosion under the dual action of chloride and sulfide solution. Corresponding protective measures are proposed.

The production of large and small heads is basically based on pressing, but the pressing process will make the hardness and density of the steel larger, but if it is not heated, cracks will easily occur.

The control of the variable diameter range, under normal circumstances, the size of the first processing range is within one level, for example, the size of the head of 325-159, basically need to be heated several times, first press the 325 pipe, put 325 The pore size is pressed to 273. This pressing also needs to be heated. The second diameter is the process of 273 variable diameter 219. This time it is also necessary to heat the tube to the specified temperature and then press. Then there is the process of 219 changing to 159, and each time the diameter is required to be heat treated.

All kinds of materials have their own hardness and tensile strength, so it is determined that the pressing strength of each material is not the same. The same type of head, the material processing method and the program will be very different, such as It is said that the size of ordinary carbon steel is formed after three heat treatments. However, the larger the hardness of the alloy material, the more the number of pressing and the number of heating, and the more complicated the molding process.