高氮无镍奥氏体不锈钢热变形工艺基础研究

发布时间：2018-09-01 07:10

【摘要】：我国是贫镍的国家,镍需要大量进口,导致奥氏体不锈钢的生产成本处于高位,为了解决这一问题,科研人员研发出了高氮不锈钢。但是关于高氮奥氏体不锈钢热加工方面的报道相对较少,尤其是与不含氮奥氏体不锈钢热加工规律的差异研究较少,因此需要在这方面进行系统研究。对铸态和锻态N0.7试验钢进行热处理,随着加热温度和保温时间的增加,两种状态的组织晶粒均呈长大趋势;为使铸态N0.7试验钢中的析出物充分溶解,同时组织中不易出现异常的长大晶粒,加热温度应低于1200℃,保温时间不超过4h。适合于锻态N0.7试验钢的加热制度为:加热温度1200℃,保温1h;铸态N0.7试验钢在800℃左右进行热处理时,原始晶粒的晶界处出现片层状析出物,其成分为Cr2N和转变后的奥氏体。研究不同变形参数(变形温度、应变速率)对N0、N0.45及N0.7试验钢热变形的影响;构造出相应的本构方程,计算出变形表观激活能QN0.45=823.31KJ/mol,QN0.7=524.84KJ/mol,QN0=479.59KJ/mol,为制定出合理的热加工工艺提供理论依据。对高温压缩变形后的试样进行组织观察,随着温度的升高、应变速率的降低,动态再结晶晶粒越多,动态再结晶进行越完全;氮含量的增加促进动态再结晶的进行。对N0.7试验钢进行高温拉伸实验。相同应变速率下,温度升高,变形抗力降低,塑性提高;1200℃时,应变速率增加,变形抗力增加,同时由于温度效应,热塑性提高。
[Abstract]:In order to solve this problem, high nitrogen stainless steel has been developed in order to solve this problem because of the high production cost of austenitic stainless steel due to the large import of nickel in China. However, there are few reports on hot working of high nitrogen austenitic stainless steel, especially the difference between austenitic stainless steel and nitrogen free austenitic stainless steel. With the increase of heating temperature and holding time, the microstructure grains of as-cast and forged N0.7 test steels show a long trend, in order to make the precipitates in the as-cast N0.7 test steels dissolve fully. At the same time, it is not easy to appear abnormal grains in the microstructure, the heating temperature should be lower than 1200 鈩，

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