Microstructure And Property Of Bainitic Hardfacing Alloy With Different Carbon Contents

With excellent comprehensive mechanical properties the bainitic steel has been used widely in the fields of ship, bridge and building material. However, a lot of bainitic steel are alloy steel. The overall manufacturing is very expensive and many work pieces only require the surface with high performance in the field of mechanical engineering. So obtaining bainite structure on the surface of the work pieces not only can reduce the cost,but also can improve performance by hardfacing technology, which is so important for the development of bainitic steel widely.In this paper, six kinds of bainitic flux-cored wires with different carbon contents(medium-low carbon and high carbon) were developed. Six groups of hardfacing alloys were prepared by submerge-arc welding. Meanwhile, the microstructures of hardfacing alloys were observed, phase composition, wear resistance and toughness were measured and analysed respectively. Then combined with the actual working condition, the changes of microstructures and properties under long-time high load abrasion were analysed deeply.Microstructures of hardfacing alloys with different carbon contents are consist of proeutectoid-ferrite, bainite, martensite and retained-austenite. The microstructures of hardfacing alloys change regularly from medium-low to high carbon. When the carbon content is 0.29 wt.% in medium-low carbon hardfacing alloys, the microstructure is mainly granular-bainite/martensite; When the carbon content is 0.54 wt.% in high carbon hardfacing alloys, the microstructure is mainly quasi lower-bainite/martensite. And the two kinds of hardfacing alloys have the excellent mechanical properties.The long-time high load abrasion of hardfacing alloys shows that γ-Fe in the hardfacing alloys is transformed into α-Fe. Because of strain retained-austenite transformed into martensite, the hardness and wear resistance on the surface can be further improved.