Si对明弧堆焊合金M_7C_3相及耐磨性的影响

采用药芯焊丝自保护明弧焊方法制备Fe-17Cr-4C-2V-Mn-Si-Ti多元合金系堆焊合金。借助金相显微镜、X射线衍射仪及扫描电镜等手段,研究硅对其M_7C_3(M=Fe,Cr,V,Mn)相及耐磨性的影响。结果表明:当硅含量从0.6%(质量分数,下同)增加到2.4%时,初生M_7C_3相由板条状转变为块状弥散分布;其相邻间隔的γ-Fe数量逐渐减少直至消失。硅改变了初生M_7C_3形核前驱体-液态合金化高碳原子团簇的属性而引起其形态、分布和尺寸改变。磨损结果表明,当硅含量从0.6%增加至2.4%时,合金耐磨性先提高后下降,至1.5%时耐磨性最佳,微切削和微观断裂两种磨损机理并存。

Effect of Silicon on M7C3 Phases and Abrasion Resistance of Open Arc Hardfacing Alloys

Fe-17Cr-4C-2V-Mn-Si-Ti complex system hardfacing alloys were deposited by using flux-cored wire self-shielded open arc welding.The effects of silicon on their M7C3 (M=Fe, Cr, V, Mn) phases and abrasion resistance were investigated by OM, XRD and SEM.The results show that, with silicon content increasing from 0.6%(mass fraction) to 2.4%, the size of primary M7C3 carbides gradually reduces and transites from rod-like shape to block-like shape in dispersion distributing state.γ-Fe phases, which adjacent to those primary M7C3 grains, progressively reduce until disappear.It dues to that silicon can change the precursor of primary M7C3 nucleates in nature, e.g.liquid high carbon atom clusters and it results in the change of their morphology, distribution and size.The wear test results indicate that the abrasion resistance of open arc hardfacing alloys improves firstly and then reduces when silicon content increases from 0.6% to 2.4%.The optimum abrasion resistance is acquired at 1.5%Si.The analysis on the surface worn morphologies show that the micro-cutting and micro-spalling wearing mechanisms coexist.