The Study Of Placed Flux Strips With Ultra Narrow Gap Welding Method

Having proved the possibility of welding with flux strips constraining arc by using welding with flux strips constraining arc to weld 5mm thick 430 ferritic stainless steels and get good weld formation. But the reason that one of the critical factors which this method is not generalized to commercial process is flux strips. The research group had designed small and independent flux bands and designed placement methods in the groove, and by using welding with flux bands constraining arc to carry on the welding tests. Because of the main problem is manufacture methods of flux strips are limited to handmade, though we had designed the fabricated equipment that made flux strips, but it can not be manufactured automatically and multitudinously. The article need to improve the automation fabricated equipments and fabricated technologies.Base on former structure of flux strips, the article designs the arrangement modes of flux bands in the groove, For fabricated process of flux bands, the article uses pressure coating method and compression method to make flux bands automatically, and studies on influence factors of making flux bands. It turned out that the craftsmanship of using compression method to make flux bands is reliable and easy to control; in the influence factors of making flux bands, the humidity of flux、the granularity of flux、the concentration-modulus of water glass、the proportion between flux powder and water glass and drying modes and so on have an effect on quality and shaping of flux bands.Using the welding with flux bands constraining arc to carry out the welding test of T-joints of two different forms of the lap joints, the research emphasis is welding procedure. It turned out that using this welding method has achieved single side welding three surface forming and got T-shape welded joints and got matching range of welding parameters by adjusting matching relations of welding parameters. Welding voltage is the main factor effecting the penetration between panel and core plate, this welding method’ heat input is small and the arrangement is 0.37~0.55KJ/mm.Aim at two different forms of the lap joints, welding with flux bands constraining arc welded T-joints are studied through microstructure analysis, hardness and mechanical tests. By using H08Mn2 Si welding wire, the first and the second forms of the lap joints of welded T-joints’ microstructure are same in the weld zone, the main microstructure is acicular ferrite; in the HAZ zone, the main different reflects in the core board, because of two different base metal of core boards, there are two different microstructures, the former’ main microstructure are granular bainite, the latter’ main microstructure are bainite and ferrite, the microstructure is same on the panel and the main microstructure are granular bainite; in the fusion zone, the main microstructures are coarse martensite and lath martensite respectively; About hardness test result, the hardness distribution is similar on the panel, The weld metal is found to be over matched in terms of mechanical properties; In the direction of the core boards, the former’ hardness distribution is similar with the hardness distribution on the panel, but aim to the latter’ hardness distribution, the hardness in the HAZ zone is higher than hardness in the weld zone and base metal, compared with the former, the latter’ hardness has increased 153.2HV; For tensile test, the former’ fracture position occurred on the base metal of core boards and close to the HAZ zone, the latter’ fracture position occurred on the weld zone of the joint of panel and core boards, and compared with the former, the loads which the latter can bear and yield strength are higher.