挤压316H奥氏体不锈钢大口径管材的晶粒度控制

Grain size control of extruded 316H austenitic stainless steel large⁃diameter pipes

系统研究了不同变形量、变形速率、冷却方式、固溶处理温度对316H奥氏体不锈钢晶粒度的影响,并开展了挤压大口径316H奥氏体不锈钢工程化试制。结果表明,变形量越大,晶粒越细小,挤压变形量为80%时,挤压后的晶粒度可达4级以上;在相同变形速率情况下,试样的晶粒尺寸与冷却方式关系明显,水冷、空冷和3 min保温再空冷方式的晶粒尺寸依次增大;在相同的冷却速度条件下,变形速率越快,晶粒尺寸越细小,但随着冷却力度的减弱,晶粒尺寸差距逐渐减少。固溶处理温度对晶粒尺寸长大的作用远大于固溶时间的作用,成形后固溶处理对晶粒的均匀化起到一定的作用,但固溶温度过高会使晶粒迅速长大,固溶处理温度和保温时间应该控制在1050℃和40 min内。

Effects of deformation amount,deformation rate,cooling method and solution treatment temperature on the grain size of 316H austenitic stainless steel were systematically studied,and the engineering trial production of the extruded large⁃diameter 316H austenitic stainless steel was carried out.The results show that the larger the deformation,the finer the grains.When the extrusion deformation is 80%,the grain size reaches finer than grade 4.Under the same deformation rate,the grain size of the specimens is obviously related to the cooling method,where the grain size increases in turn for the specimens with water⁃cooling,air⁃cooling and holding for 3 min then air⁃cooling.Under the same cooling rate,the higher the deformation rate,the finer the grain size,but with the decrease of cooling rate,the difference in grain size decreases gradually.The effect of solution treatment temperature on the increase of grain size is much greater than that of the solution time.The solution treatment is effective to homogenize the grain size after extrusion,but the grain size grows rapidly if the solution treatment temperature is too high.The solution treatment temperature and time should be controlled within 1050℃and 40 min.