1、Since the alloy element and nitric atom segregate on the austenite crystal boundary, the vein-like structure is formed.
2、A new method for showing the prior austenite crystal boundary corrosion, of pipeline steel has been also supposed.
3、The results shows that the corrosion is an ideal austenite crystal boundary corrosion for pipe line steel. The accuracy of adopted determination method is high.
4、In composites contained 1.5%C, VC particles were along austenite crystal boundary, while others of 3%C content were distributed uniformly.
5、The results show that the precipitated austenite crystals of welded joint after solid solution treatment are fewer, the grains are smaller. And the shape of austenite changes from strip to roundness.