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一引言有关非平衡组织加热时的相变问题,引起了普遍的重视。目前国内外对加热时马氏体的组织转变研究得较多,所得出的结论大致可归纳为两种:1.在Ac_1以上加热速度愈慢,或在Ac_1～Ac_3的低温侧保温,然后再加热到Ac_3以上,会导致原粗大奥氏体晶粒的遗传;反之,如果在Ac_1以上的温度采用快加热,则有助于晶粒的细化。2.快加热或慢加热均会导致奥氏体晶粒的遗传。当加热速度约为200～300℃/分时,可以观察到奥氏体晶粒细化。但是,我们的生产实践和某些有系统的试验结果表明,一般不吻合上述的结论,特别是12CrNi3、
I. INTRODUCTION The issue of phase transition when unbalanced tissue is heated has attracted widespread attention. At present, there are a lot of researches on the transformation of martensite during heating. The conclusions can be summarized into two kinds: 1. The slower the heating rate at Ac_1 or the lower temperature side of Ac_1 ~ Ac_3, and then Heating above Ac_3 will result in the inheritance of original coarse austenite grains. On the other hand, if the temperature is above Ac_1, rapid heating will help to refine grains. 2. Rapid heating or slow heating will lead to austenite grain genetic. When the heating rate is about 200 ~ 300 ℃ / min, the austenite grain refinement can be observed. However, our production practices and some systematic tests show that the above conclusions are generally not consistent, especially 12CrNi3,