过共晶高硼堆焊合金的显微组织及耐磨性

Microstructure and Abrasion Resistance of Hypereutectic High-boron Hardfacing Alloys

采用药芯焊丝埋弧堆焊方法制备含有0.1~1.0 C,4~13 Cr,2.5~3.2 V,2.2~3.8 B（质量分数/%）的过共晶高硼合金。借助光学显微镜、扫描电镜、X射线衍射等手段,研究其显微组织及硼化物分布形貌。结果表明：显微组织由铁素体＋马氏体＋残余奥氏体＋M2B＋M3（B,C）＋V2C等组成,其初生M2B相的数量随硼含量而改变。此外,考察碳含量对高硼堆焊合金硬度及耐磨粒磨损性能的影响,实验表明,高硼堆焊合金硬度HRC高达66.5,耐磨性优良,随着碳含量增加,硬度和相对耐磨性ε先升高,然后下降,其磨损机制从磨粒的显微切削逐渐转变为微观断裂和显微切削共存。

Hypereutectic high-boron hardfacing alloys containing 0.1-1.0 C,4-13 Cr,2.5-3.2 V,2.2-3.8 B（mass fraction/%） were deposited by using submerged arc welding（SAW） flux-cored wire.The microstructure and boride morphology were investigated by optical microscopy（OM）,scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The microstructure consists of ferrite,martensite,residual austenite,borides and carbide such as M2B,M3（B,C）,V2C,etc.The volume fraction of primary boride M2B varied with boron content.In addition,the effects of carbon content on hardness and wear properties of high-boron hardfacing alloys were evaluated.The results showed that the hardness value was up to HRC 66.5 and the abrasion resistance was excellent.With the increased of carbon concentration,both the hardness and abrasion resistance firstly enhanced,and then decreased.The wear mechanism changed from abrasive particle micro-cutting to micro-area spalling together with micro-cutting.