Application of External Electromagnetic Forces for Resistance Spot Welding of Р6М5 Instrumental Steel Parts

Abstract

Background. Joining of working part of the instrument using mechanical methods or brazing doesn’t ensure its good fixation and isn’t technologically reasonable for mass production purposes. This problem can be solved by application of electromagnetic forces for resistance welding methods based on physical effect on joint formation process. Objective. The aim of the paper is estimation of technological possibilities of resistance spot welding with electromagnetic stirring for joining of instrumental steels. Methods. Transversal opposite-symmetric magnetic field is generated in the working zone. It has equal value but opposite direction of magnetic induction relative to contact plane of parts to be joined for stirring of molten metal with ponderomotive forces. Results. Positive changes of parameters of joint formation were detected. They define mechanical properties of joints. Control of molten metal hydrodynamics resulted in decreasing of sponginess-type imperfections in the central area of the nut. It was shown that changes in thermal processes, leading to decreasing of cooling speed, result in decrease of hardened structures in the moulded zone which, in turn, results in decreasing of microhardness of structure elements. Conclusions. Reasonability and effectiveness of application of electromagnetic forces for resistance spot welding of instrumental steels was proven.

Keywords

• Instrumental steels
• Resistance spot welding
• External electromagnetic forces
• Ponderomotive forces
• Mechanical properties