亚共晶Fe-Cr-B-C系堆焊合金的组织及耐磨性

Microstructure and Wear Resistance of Hypoeutectic Fe-Cr-B-C Hardfacing Alloys

采用药芯焊丝气保焊堆焊方法制备了0.8%~1.6%C（质量分数）的亚共晶Fe-Cr-B-C系耐磨合金,采用光学显微镜,扫描电镜和X射线衍射仪对堆焊合金微观组织和物相进行了分析。结果表明：堆焊合金显微组织是亚共晶组织,由初生γ-Fe枝晶和共晶组织（硼碳化物＋共晶基体）组成;元素C能显著增加共晶组织数量,增加共晶组织上共晶基体的尺寸;堆焊合金的耐磨性能主要受作为耐磨骨架的共晶组织数量和形态共同影响,0.8%C堆焊合金的共晶组织数量较少,相对磨损性能仅为9.1;当C含量增加到1.2%时,共晶组织数量明显增加,堆焊合金的磨损性能显著上升至17.2;继续增加C到1.6%时,共晶组织数量最多,但是由于共晶基体尺寸偏大,堆焊合金的磨损性能大幅降低至11.4。

Hypoeutectic Fe-Cr-B-C hardfacing alloys with 0.8%-1.6% C were deposited by flux-cored wire using metal active gas arc welding. The microstructure and phases morphology were investigated by optical microscopy（OM）,scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The results show that the alloys are hypoeutectic with primary austenite and eutectic structure（boron carbide ＋ eutectic matrix）. The volume fraction of eutectic structure and the size of eutectic matrix increased with the C content increasing. The wear resistance of hardfacing alloys is affected by the volume fraction and morphology of eutectic structure. Because of less eutectic structure, the relative wear resistance of 0.8% C hardfacing alloy is just 9.1. When the content of C increases to 1.2%, the relative wear resistance of hardfacing alloys rises significantly to 17.2 for the volume fraction of eutectic structure increasing. When C is added to 1.6%, lots of eutectic structure appear, the relative wear resistance property significantly decreases to 11.4 for the big size of eutectic matrix.