What is the relationship between the cracking of stainless steel tensile parts?
The radius of the punch fillet is too small and too sharp, which is prone to cracks. Therefore, the method of repairing the mold is to increase the fillet as much as possible and polish it if the product specifications allow, and be careful not to be too sharp. The use of special drawing oil can also play a good anti-crack effect, but it should be noted that the lubricant is only suitable for the working surface of the die, and the lubricant should not be in contact with the punch, because the punch and the blank surface will produce good cracks. friction, preventing the material from sliding, cracking and thinning.
Stainless heat-resistant steel and austenitic stainless steel are more common, and these two materials are used as examples. The specific reasons are as follows:
Austenitic stainless steel: Austenitic stainless steel produces delayed cracks due to its own structure. Austenitic stainless steel has a large degree of work hardening. After stretching, in addition to the residual internal stress caused by cold working, the austenitic structure is There is also some martensitic transformation in the mouth, so the mouth of the mouth should be prevented from cracking. In order to eliminate residual stress and eliminate martensite structure and make it undergo phase transformation at high temperature, taking 304 as an example, the annealing temperature of austenitic stainless steel is 1010~1050℃. The mouth of the extension is annealed, and the faster one is high-frequency annealing.
For cylindrical drawn parts, when the diameter is greater than or equal to 0.8 and the diameter is greater than or equal to 300, annealing treatment is required. Of course, if cracks occur when the aspect ratio is less than 0.8, annealing should be arranged immediately.
Ferritic stainless steel: no phase change occurs after stretching. The main reason for product cracking is residual stress, which can ensure safety. From experience, for cylindrical drawn parts, when the diameter is greater than or equal to 0.8 , when the diameter is greater than or equal to 300, annealing treatment is required. If the height-diameter ratio is less than 0.8, cracks will appear, and annealing should be arranged immediately.
The above content is related to what is related to stainless steel cracking, and what problems will occur in the production process. In fact, many experienced workers can prevent it in advance. Only by reading and analyzing more can a lot of waste can be avoided. I hope the above content is correct. Readers help.