线材表面对称粗晶形成原因分析

针对超低碳钢高速线材盘条尾部表面对称粗晶进行了研究，分析了粗晶出现的位置、表面组织形态及相应的生产工艺环节。结果表明：线材表面对称粗晶是由于线材尾部在吐丝前夹送辊夹持时产生微变形，其表面奥氏体晶粒并没有发生动态再结晶晶粒细化，而是在随后的缓慢冷却过程中发生了奥氏体的静态再结晶晶粒粗化，尤其在表层以下的近表面的位置，晶粒以迅速长大的方式向表面变形储存能较高的区域推进，将夹送辊夹持带来的变形能释放，从而造成表面局部奥氏体晶粒异常粗大。为此，改变夹送辊的孔型设计，可解决线材表面对称粗晶问题。

Cause analysis of symmetrical grain coarsening on the surface of wire rods

In view of the symmetry coarse grain on the surface tail of the high speed wire rod of ultra low carbon steel,the coarse grain appeared position,surface morphology and the corresponding production process were analyzed.The results show that the surface of the wire symmetrical coarse grain is due to the pinch roll clamping deformation before laying.The austenite grain do not occur dynamic re-crystallization refinement on the surface of wire,but grow coarsening in the subsequent slow cooling occurred in the process of austenite static re-crystallization.Especially in the near surface position below the surface,the grain rapidly grow up to the surface region with higher deformation stored energy,and release the pinch roll clamping deformation energy,which resulting abnormal coarse austenite grain on local surface.Therefore,changing the groove design of pinch roll,can solve the problem of wire rod surface symmetry coarse grain.