无熔滴电弧热丝GTAW自润滑耐磨堆焊层组织及性能

Microstructure and Performance of Self-lubricating Anti-abrasion Composite Layer by Non-droplet Arcing Wire GTAW

目的采用无熔滴电弧热丝GTAW堆焊技术,在Q235钢表面堆焊具有自润滑功能的含石墨相耐磨合金。方法设计含有镍包石墨粉的药芯焊丝,并使用无熔滴电弧热丝GTAW堆焊技术和传统GMAW两种方法进行对比堆焊。焊后,采用销盘式摩擦磨损试验机对堆焊层进行对比摩擦磨损性能测试,利用光学显微镜、SEM和EDS研究堆焊层的微观结构及成分,并对磨损面形貌进行对比分析,探究自研焊接系统制备含石墨相堆焊层的工艺特点和堆焊层自润滑耐磨性能。结果无熔滴电弧热丝GTAW可以有效降低母材的稀释率,保证药芯焊丝自润滑石墨相过渡,且能提高熔敷率。堆焊层形成了Fe-Cr-B耐磨基体,并在晶界处分布大量的颗粒状石墨相。摩擦磨损实验中,堆焊层摩擦系数可低至约0.65,随着摩擦时间的延长,摩擦系数进一步减小,磨损面未发现典型犁沟,表面平滑且呈黑色,堆焊层具有自润滑功能,且摩擦系数与焊接参数有关。传统GMAW方法制备的堆焊层的摩擦系数为1.4左右,且随着磨损时间的延长,摩擦系数略有增大。结论无熔滴电弧热丝GTAW堆焊技术低热输入和高熔敷率的工艺特点适合堆焊,尤其适合防止焊丝化学成分烧损的堆焊。在合理控制工艺参数,焊接稳定的前提下,选择低辅助电流,可以成功制备含石墨相的自润滑耐磨堆焊层。

The work aims to overlay the self-lubricating anti-abrasion alloy with graphite phase on the Q235 steel by non-droplet arcing wire GTAW.The nickel-coated graphite flux-cored wire was designed and introduced into the overlay by the non-droplet arcing wire GTAW and the traditional GMAW for comparison.After welding,the pin-and-disc friction and wear tester were used to compare the anti-abrasion and wear resistance of the overlay.OM,SEM and EDS were accomplished to study the microstructure and component of the overlay and analyze the wear morphology.The processing characteristic of preparing overlay with graphite phase by welding system and the self-lubricating anti-abrasion performance of the overlay were analyzed.Non-droplet arcing wire GTAW could effectively inhibit the dilution ratio of the substrate,ensure the transition of the graphite phase in fluxed cored wire and improve the deposition rate.Fe-Cr-B anti-abrasion substrate was formed on the overlay and a lot of granular graphite phase was observed at the boundary.The friction coefficient under the friction and wear test could be as low as 0.65 and decreased further with increasing friction time.No typical furrow was found on the wear surface which was smooth and black and belonged to self-lubricating wear type,and the friction coefficient was related to welding parameters.The friction coefficient of the overlay prepared by the traditional GMAW method was about 1.4,and slightly increased with the prolonging of wear time.Non-droplet arcing wire GMAW has the characteristics of low heat input and high deposition rate,which is suitable for overlay,especially for overaly to prevent the chemical composition of welding wire from burning out.Under the premise of reasonable control of process parameters and stable welding,self-lubricating anti-abrasion overlay containing graphite phase can be successfully prepared by selecting low auxiliary current.