PRODUCTION OF THE HIGH STRENGTH AUSTENITIC STAINLESS STEEL SHEET HAVING ULTRAFINE GRAIN

调查人员已经成功地在超级谷物精炼中完成了基于Fe-Cr-Ni系统由Martensite Austenite reversion的0.5 mum的metastable Austenitic不锈钢。目前这项工作的目标是找到的，三种条件应该对谷物超级精炼感到满意： （1）奥斯汀的转变几乎所有的人，由冷卷。（2）《火星人对奥斯汀的完全逆转》，相对较低的温度被退火。（3）在房间温度下存在逆转的澳大利亚的温度女士。下一个目标是确定高强度钢含有分子溴和硝基的合适化学成分。最后，使用了370公斤，热机械治疗已经在钢铁工作中运送到了试点线上。然后，张力特性和压力成形特性已经被测试了。所取得的结果如以下;1.铁-铬-镍系统中超精谷物钢的典型组成是铁-15.5%Cr-10%Ni。一种具有90%冷滚动的特殊物质，使其退火至600 ° C-10分钟。has the ultra\grain with the mean size of 0.5 mum，giving 0.2%proof stress of about 70 kgf/mm^2.2。13%Cr-10%Ni-2.5%Mo-0.12%N钢与15.5%Cr-10%Ni钢相比增加了强度。它被认为是由molybdenum和nitrogen制作的Austenite Grain比固体的Soul Harding。在翻新治疗后，这种高强度钢具有0.2毫米的奥氏体颗粒，给予100千克f/毫米^2的0.2%的证明压力，120千克f/毫米^2的拉伸强度，35%的长度。该高强度钢是{110}类型的结构。深度绘图是不够的，因为n和r的价值相对低于18-8年的奥地利钢。因此，这种钢材是有可能使用的零件不需要各种形式的，例如，用于铁路振动的Austenitical Steinless。

Investigators have already succeeded in super grain refining to 0.5mum of metastable austenitic stainless steels based of Fe-Cr-Ni system by martensite austenite reversion. The purpose of this present work is to found that three conditions should be satisfied for the grain super refining : (1) Austenite transforms to martensite almost all, by cold rolling. (2) The martensite perfectly reverses to austenite by annealing at relatively low temperature. (3) Ms temperature of the reversed austenite exist under the room temperature. Next purpose is to determine the suitable chemical composition for the high strength steel containing molybdenum and nitrogen. Lastly, using 370kg ingot, the thermo-mechanical treatments were carried out on the pilot line in steel works. And then, the tensile properties and press formabilities were examined. Results obtained were as follows;1. Typical composition of ultrafine grain steel in Fe-Cr-Ni system was Fe-15.5%Cr-10%Ni. A specimen with 90% cold rolling prior to annealing of 600゜C-10min. has the ultrafine grain with the mean size of 0.5mum,giving 0.2% proof stress of about 70kgf/mm^2.2. The strength of 13%Cr-10%Ni-2.5%Mo-0.12%N steel increased in comparison with 15.5%Cr-10%Ni steel. It is attributed to refining of austenite grain rather than solid soution hardening by molybdenum and nitrogen. After reversion treatment, this high strength steel has an austenite grain of 0.2mum, giving 0.2% proof stress of 100kgf/mm^2, a tensile strength of 120kgf/mm^2 and an elongation of 35% respectively.3. The texture of this high strength steel was of {110} type. A deep drawability was not enough, because both values of n and r were relatively lower than 18-8 austenitic steel. Therefore,this steel will be able to used for the parts not required the severe forming, for example, austenitic stainless for railroad vihicles.