20钢高压管脆断分析

BRITTLE FRACTURE ANALYSIS OF 20 STEEL HIGH PRESSURE PIPING

采用金相显微镜和透射电镜显微分析、力学性能试验与有限元分析等方法 ,系统分析合成氨系统使用的 2 0钢高压管发生脆断的原因。认为发生脆断的主要原因是由于钢中氮等元素在管道冷加工后形成Cottrell气团 ,从而产生应变时效所致。建议 2 0钢等低碳钢应严格控制其中氮等元素含量 ,控制管道弯制等成型的温度 ,避免发生冷加工现象 ,对必需的冷加工应进行应变时效试验 ,这样才能避免 2 0钢等高压管道脆断的发生。

It is systematically analyzed the reason of brittle fracture taking placed at the 20 steel high pressure piping used in the ammonia synthesis system by the methods of micro analyses of metallographic microscope and transmission electron microscope, mechanical property experiments and finite element analysis etc. The occurrence of brittle fracture is considered to be mainly caused by strain aging after cold working to the pipe when the steel containing sufficient Nitrogen and the other chemical element. So that, in order to avoid the phenomenon of cold working, it is suggested that the Nitrogen and the other chemical elements contained in low Carbon steels such as 20 steel, and forming temperatures of the pipe bending, etc. should be strictly controlled. If the cold working to the steels must be required, the experiment of strain aging should be carried out to them. After then the brittle fracture at 20 steel etc. high pressure piping can be avoided.