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

具有超细晶粒的高强度奥氏体不锈钢板的生产

基本信息

批准号：
62850135
负责人：
TOKUNAGA Youichi
金额：
$ 4.86万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

项目摘要

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.

研究人员已经成功地通过马氏体奥氏体逆转将基于Fe-Cr-Ni系统的亚稳奥氏体不锈钢的晶粒细化到0.5 μ m。本文的目的是发现晶粒超细化应满足三个条件：（1）通过冷轧，奥氏体几乎全部转变为马氏体。(2)通过在相对低的温度下退火，马氏体完全逆转为奥氏体。(3)在室温下存在着反转奥氏体的Ms温度。下一步的目的是确定含钼和氮的高强度钢的合适化学成分。最后，用370 kg钢锭在钢厂中试生产线上进行了形变热处理。然后，测试拉伸性能和压制成形性。结果如下：1. Fe-Cr-Ni系超细晶粒钢的典型成分为Fe-15.5%Cr-10%Ni。在600 ℃-10分钟退火之前进行90%冷轧的试样。具有平均尺寸为0.5 μ m的超细晶粒，提供约70 kgf/mm^2.2的0.2%屈服强度。13%Cr-10%Ni-2.5%Mo-0.12%N钢的强度比15.5%Cr-10%Ni钢有所提高。这是由于钼和氮对奥氏体晶粒的细化而不是固溶硬化。该高强度钢经回复处理后，奥氏体晶粒尺寸为0.2 μ m，0.2%屈服强度为100 kgf/mm^2，抗拉强度为120 kgf/mm^2，延伸率为35%。该高强度钢的织构为{110}型。深冲性是不够的，因为n和r的值都相对低于18-8奥氏体钢。因此，该钢可用于不需要剧烈成形的零件，如铁路车辆用奥氏体不锈钢。