轴向压力对X65合金钢摩擦堆焊层组织和磨损性能的影响

Axial Pressure Effects on Microstructure and Wear Resistance During Friction Surfacing of X65 Alloy Steel

为拓宽摩擦堆焊的工程化应用,以X65钢作为耗材和基板材料进行了摩擦堆焊工艺试验研究,在选定最优焊速的基础上,主要讨论了轴向压力与堆焊层组织、显微硬度及磨损性能的影响。试验表明：在转速4 000 r/min、堆焊速度200 mm/min、轴向压力在59.7~104.4 MPa范围下可获得冶金连接与成型良好的摩擦堆焊层。随轴向压力增加,堆焊层宽度增加、但厚度减小;过高轴向压力不能增加摩擦堆焊层的有效体积。摩擦堆焊接头主要由堆焊层、热影响区（HAZ）和母材区域组成,与传统摩擦焊缝细小晶粒组织特征不同,摩擦堆焊层主要为粗大板条和粒状贝氏体混合组织特征。HAZ主要由过热区和相变重结晶区组成,过热区主要为贝氏体组织特征,而重结晶区为细小铁素体晶粒组织特征。轴向压力变化对堆焊层组织粗化倾向和HAZ尺寸有较大影响,但对HAZ的组织形态影响不大。不同轴向压力下的堆焊层平均硬度及抗磨损性能均高于母材,与母材比较堆焊层磨损体积最大可降低33.3%。

To broaden the engineering application of friction surfacing, experiments using X65 steel as the substrate and consumable rod were performed. The optimal surfacing speed was selected, and the effects of axial pressure on microstructures, microhardness and wear resisting properties were discussed. Results that the coatings with better bonding and shaping qualities are obtained under the conditions of 4 000 r/min, 200 mm/min and 59.7-104.4 MPa. The width of the coating increases. However, the thickness is decreased with increasing axial pressure. The excessive pressure decreases the effective volumes of the coatings. Friction surfacing joints consist of surfacing coating, heat affect zone （HAZ） and base metal, and the surfacing coatings are composed of coarser lath and granular bainites rather than fine equiaxed grain structures as found in conventional friction welds. The HAZ consists of the overheated zone and phase change recrystallization zone. The overheated zone has bainite features and the recrystallization zone has fine ferrite features. The variation of axial pressure has greater influence on the coarser tendancy of coating microstructure and the size of HAZ, but smaller effects on the microstructure types. Both the average hardness and wear resisting properties of the surfacing coatings are better than that of the base metal for different axial pressures, and the wear volume can be reduced to 33.3% compared with the base metal.