Analysis on Cracking of 304 Stainless Steel Pipe in Drawing Process

The extension rate of 304 stainless steel pipe is low, the elastic modulus E is larger, the hardening exponent is higher, and the thickness is small (304 stainless steel pipe is 0.9 ~ 0.11, soft steel is 1.3 ~ 2.0). The 304 stainless steel pipe material is short in the plastic deformation stage, especially its plastic strain ratio. 304 stainless steel pipe sheet pull deep cracking sometimes occurs after pull deep deformation, and the gambling company sometimes occurs when the deep part is pulled out from the concave mold. Sometimes occurs when a deep deformation is subjected to impact or vibration; It can also occur after a period of storage or use after a deep deformation. This paper analyzes the causes of defects in 304 stainless steel pipe plate drawing, and puts forward some solutions.

1. Reasons for cracking formation

Austenitic 304 stainless steel pipe has a high hardening index (304 stainless steel pipe is 0.34). The austenitic type 304 stainless steel pipe is a stable type, and the phase transition occurs when the deformation occurs, which induces the martensite phase. The martensite is brittle and therefore prone to cracking.

In the case of plastic deformation, with the increase of deformation, the higher content of martensite, the greater the residual stress, and the more likely to crack in the process of processing.

The reasons for the formation of surface scratches

304 stainless steel pipe the scratch on the surface of the deep drawing is mainly due to the workpiece and die surface relative motion, to a certain pressure, under the action of the local surface of billet and the mold friction directly, combined with the deformation of the billet hot billet and scrap metal deposition in the mold on the surface, the surface scratch scratch.

Source: China Steel Pipe Manufacturer - Yaang Pipe Industry Co., Limited (www.yaang.com)