高强焊丝用H10Mn2SiNiMoTi盘条拉拔横裂分析

某高强焊丝用盘条在拉拔过程中出现很多横向断裂裂纹,采用扫描电镜、金相显微镜、直读光谱仪、显微硬度计等设备对断裂试样进行检测分析,结果表明,断裂的盘条化学成分和金相组织正常,夹杂物不严重,引起横裂产生的主要原因是边部的马氏体组织。焊丝在拉拔过速或者拉拔时润滑条件差的情况下,焊丝圆周与模具的接触位置摩擦生热,在高温下发生奥氏体相变,后续冷却又形成了马氏体组织。马氏体组织硬度高、脆性大,在焊丝拉拔轴向拉应力的作用下产生了横向开裂。

Analysis on Transverse Crack of H10Mn2SiNiMoTi Wire Rod for High Strength Welding Wire

Many transverse cracks appear in a wire rod for high strength welding wire in the drawing process. The fractured specimens are tested and analyzed by scanning electron microscope and metallographic microscope, direct-reading spectrometer and microhardness tester. The results show that the chemical composition and internal metallographic structure of the fractured welding wire rod are normal, and that the inclusion situation is not serious. The main cause for transverse crack is the martensite structure at the edge. When the welding wire is drawn too fast or the lubrication condition is poor during drawing, heat is generated by friction of contact position the between the welding wire and mould. The austenite transforms at high temperature, and turns to be martensite after being cooling. The martensite has high hardness and brittleness, so transverse cracking occurs under the action of axial tensile stress of wire drawing.