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本文对20Cr1Mo1VNbTiB钢退火组织中发现的“粗晶”进行了金相形貌及X射线结构分析,并以电子探针进行微区成分对比研究。对Ac_1～Ac_3区间不同加热条件下的组织进行了对比观察。结果表明,被原初生奥氏体晶粒所遗传的“粗晶”,并非由简单的晶粒所组成,是由加热过程中形成的针状r相长大,汇聚的结果。其形成是与附近碳化物具有密切关系,长大受到α相的回复所限制,整个转变过程属于扩散型相变。研究表明,采用适当热处理工艺,可有效消除和避免“粗晶”的产生。
In this paper, the microstructure and X-ray structure of “coarse grain” found in the annealed microstructure of 20Cr1Mo1VNbTiB steel were studied. The tissues under different heating conditions of Ac_1 ~ Ac_3 were compared. The results show that the “coarse grains” inherited by primary austenite grains are not composed of simple grains and are the result of the acicular r-phase formed and heated during heating. Its formation is closely related with the vicinity of the carbide, growth by α-phase recovery limit, the entire transition process is a diffusion-type phase transition. Studies have shown that the use of appropriate heat treatment process can effectively eliminate and avoid the “coarse grain” of the production.