82B线材脆性断裂原因分析

82B线材在终轧后冷速过快导致表层出现马氏体是引起脆性断裂的原因之一.心部成分偏析导致奥氏体过冷,从而使马氏体出现在轴心部位,在拉拔过程中轴心马氏体断成竹节状,变成脆性断裂的裂纹源.大型脆性的夹杂物也是引起线材脆性断裂的起源.

Analysis on Causes to Embrittlement Fracture of 82B Wire Rod

One of the causes to the embrittlement fracture of the 82B wire rod is found to be the over speed cooling after finish rolling,which leads to formation of martensites over the surface of the 82B wire rod.Central segregation of the compositions leads to the over-cooling of the austenites which will transform into martensites in the central part and in the process of drawing the martensites in the central part,which are probably broken into the bambooknot-shaped ones are assumed to be the initial cracks of the embrittlement fracture.In addition,the larger inclusions are also an origin of the embrittlement fracture of the wire rod.