药芯焊丝耐磨堆焊过程中FB树脂对碳化钨颗粒的热保护作用

Effect of heat protection of FB phenolic resin on tungsten carbide particles in hardfacing with flux-cored wire

为了减轻堆焊过程中碳化钨颗粒的熔化及溶解烧损,采用FB树脂作为热保护剂对铸造碳化钨颗粒进行了表面包覆处理,并对制作的药芯焊丝进行了TIG焊堆焊试验。用金相显微镜、扫描电镜和能谱仪对堆焊层的微观组织和碳化物形貌进行观察分析,结果表明:采用FB树脂保护的碳化钨颗粒在堆焊过程中的熔化及溶解烧损明显降低,堆焊后复合层中保留了大量的碳化钨颗粒,颗粒周围的碳元素含量较高。热绝缘剂的使用与否对基体显微硬度的影响较大,而对堆焊层表面的洛氏硬度影响较小。此外,还通过湿砂橡胶轮磨损台对药芯焊丝进行了磨损实验,结果表明:采用了热保护的堆焊层在磨损试验中能够有效地阻碍砂粒的犁削作用,从而使耐磨性大大增加。

The FB phenolic resin was coated on the surface of cast tungsten carbide particles as heat protection material for decreasing the dissolution of particles in the process of welding. The flux-cored wire was made with the particles as core. The iron-based tungsten carbide wearable composite coa- tings on mild steel were prepared by means of TIG welding. OM, SEM and EDS were used to observe and investigate the microstructure of the welded Coating and carbide morphology. The results indicate that the melt of the tungsten carbide particles protected by FB resin is obviously lower and a lot of tungsten carbide particles are kept in the layer. The content of C element around particles is higher. The effect of heat protection on microhardness of matrix is large and on Rockwell hardness small. The results of evaluating abrasion resistance through wet sand rubber wear tests show that the overlaying layer with particles protected by FB resin can effectively prevent the cut of sands thus to greatly im- prove abrasion resistance.