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本文从两方面研究了影响钢中奥氏体晶粒粗化的现象。即一方面从AlN的溶解和析出行为对晶界的钉扎作用出发,考虑阻碍晶界迁移的阻力来源和大小。另方面从原始奥氏体晶粒和起始晶粒的大小及晶粒度不均匀因子对晶界迁移的驱动作用出发,考虑不同热处理条件下,诸因素对晶界驱动力的影响。研究结果表明,当AlN粒子的尺寸小于临界尺寸γ_(crit)且弥散度较高时,才能起到钉扎晶界的作用;当原始奥氏体晶粒和平均起始晶粒粗大且不均匀因子较小时,则驱使晶界迁移的作用力较小。如果上述两方面的条件不能满足,将使奥氏体晶粒发生粗化。除此而外,本文对我国长期以来沿用的“奥氏体本质晶粒度”的概念提出了不同的看法,认为“本质晶粒度”的概念是含糊不清的,是值得商榷的。
This article from two aspects studied the phenomenon of austenite grain coarsening in steel. That is, on the one hand, starting from the pinning effect of AlN dissolution and precipitation on the grain boundaries, consider the source and size of the resistance that impedes the migration of grain boundaries. On the other hand, from the effect of the size of the original austenite grain and the initial grain size and the grain size unevenness factor on the grain boundary migration, we consider the influence of various factors on the grain boundary driving force under different heat treatment conditions. The results show that when the size of the AlN particles is smaller than the critical dimension γ crit and the dispersion is high, the grain boundaries can be pinned. When the original austenite grains and the average starting grains are coarse and inhomogeneous When the factor is smaller, the force that drives the grain boundary migration is smaller. If these two conditions can not be met, austenite grains will be coarsened. In addition, this paper puts forward different opinions on the concept of “intrinsic grain size of austenite”, which has been used for a long time in our country, and holds the view that the notion of “intrinsic grain size” is ambiguous and worthwhile Negotiable.