Researche On The Influence Of Deformation And Temperature On The Austenitic Stainless Steel Performance

Cryogenic pressure vessel head at low temperature widely adopts Austenitic stainless steel materials, and takes its shape through spinning and stamping technologies. At present, however, problems such as splitting often happen during the process of using Austenitic stainless steel head, which has aroused high attention of producers, users and examiners. According to the analysis of the statistics about many Austenitic stainless steel head splitting cases, most of the cracks are in the excessive arc and straight flange, ie., the places where plastic deformation can be produced during the process of spinning and stamping technologies. And some relevant research shows that the large amount of martensite produced in the process of deformation is the main cause of the cracks. To solve this problem, this paper mainly studies the adverse impact of the deformation martensite on the performance of Austenitic stainless steel. And it also studies the driving characteristics of martensite change in Austenitic stainless steel in the process of all kinds of simulation technologies under different temperature, different deformation amount and different deformation speed. The result will provide valuable referential suggestions as well as basic data to the head processing technologies.The main researches and their results of this paper are as follows:(1) Different tests——including tensile test, impact test, hardness test, Intergranular Corrosion test and Stress Corrosion test——are carried out to the Austenitic stainless steel containing different amount of deformed martensite. The influence of martensite phase transition to the deterioration of material performance is studied, and the cause of the cracks in the large deformation area are determined, which is the over-containing of deformed martensite caused by the deformation technology.(2) Through the simulating deformation means of universal testing machine in lab, the impact of deformation parameter(deformation amount and strain speed) on three kinds of usual Austenitic stainless steels(S30408, S30403, and S31608) is studied. And the impact of deformation amount on the deformed martensite produced by the three kinds of materials is analyzed, and found out tendency changes of the impact of strain speed on deformed martensite in different deformation stages.(3) Through constructing low-temperature Metallography observing platform, the research on the stability of Austenitic stainless steel texture under the circumstance of deep-cold low temperature is done. Through the research about the coupling effect of temperature on the deformed martensite, some economic and feasible suggestions about head formation technologies are put forward. Spinning and stamping means are taken, and the temperature should be controlled above 80?.