1 绪言最近,通过a+r二相区轧制改善钢的韧性的方法发展异常迅速,二相区轧制与传统的通过细化晶粒和控制热处理的组织转变来改善钢韧性的方法根本不同,其最大特点是:由于轧制织构的形成,在主裂纹萌生或传播之前,生成平行板面的层状裂纹。由于缓和了应力集中。轧向及横向(以下分别称为L向、C向)的韧性得到显著改善。与轧面平行的层状裂纹一般称为分层,就其形成机理有各种说法。最初认为分层形成的主要原因是沿轧向延伸的MnS。然而,甚至在不含Mn、s的极低碳素钢中也见到有分层发生,这就否定了MnS引起分层的说法。一般还认为由于平行轧面的 1 INTRODUCTION Recently, the method of improving the toughness of steels through the a + r two-phase zone has developed exceptionally rapidly. The methods for improving the toughness of steel by two-phase zone rolling and the conventional microstructure modification by refining the grains and controlling the heat treatment are fundamentally different , Its most prominent feature is: due to the formation of rolling texture, the main crack initiation or propagation, the generation of parallel plate-shaped layer of cracks. Due to ease the stress concentration. The toughness in the rolling direction and in the lateral direction (hereinafter referred to as L direction and C direction, respectively) is remarkably improved. Layered cracks parallel to the rolling surface are generally called delamination, and there are various explanations for their formation mechanism. Initially considered the main reason for the formation of stratified MnS extending along the rolling direction. However, delamination was seen even in very low carbon steels that did not contain Mn, s, which denied that MnS caused delamination. Generally considered because of the parallel rolling surface