Welding method for mig automatic welding of cemented carbide and steel

Abstract

The invention discloses an automatic MIG (metal-inert gas) welding method for hard alloy and steel. The automatic MIG welding method includes steps of firstly, removing surface oil stain and an oxidation film layer on welded surfaces of welded materials which are hard alloy and steel in thickness ranging from 2mm to 6mm and are uniform in thickness; respectively fixing the hard alloy and the steel on a worktable of a robot position changing machine, keeping a gap between the welded surface of the hard alloy and the welded surface of the steel within 1mm; delivering protective gas which is argon gas or helium gas, adjusting protective gas flow within 15-25L / min; moving a welding gun over the welding surfaces of the welded materials, starting automatic welding and finally performing post-welding inspection. Accordingly, the problems of low productivity, proneness to generating cracks at welding joints and the like in the prior art can be effectively solved, binding force between the hard alloy and the steel is improved, automation level of welding of the hard alloy is improved, durability of the welding joints of the hard alloy is improved, and strength and durability are integrated.

Description

technical field [0001] The invention relates to the technical field of cemented carbide connection, more specifically, relates to a welding method for MIG automatic welding of cemented carbide and steel. Background technique [0002] The carbide content of cemented carbide is usually between 70-97wt%, and the average grain size is between 0.2μm-20μm (market products). Among them, WC-Co-based cemented carbide is more common and is often used in tools and cutting tools, oil and gas transportation Preparation of tooling equipment, etc. It is usually applied in the form of solid carbide, tungsten carbide coating, thick plate connectors, and thin plate connectors; it comprehensively utilizes the strength and toughness of cemented carbide, the hardness of carbide coating, stainless steel / carbon steel / Invar alloy, etc. The steel structure can meet the actual needs of certain parts of the structure for high temperature resistance, heat resistance, and corrosion resistance. In orde...

AI Technical Summary

Problems solved by technology

[0003] However, the sintering process has certain restrictions on the product size; there are strict requirements on the equipment; and cracks will appear at the bonding interface during the secondary welding process between the sintered part and the substrate

That is to say, although the sintering method can easily solve the problem of combining cemented carbide and steel, the degree of automation is low, which limits industrial production, and there is also a large tendency to crack in the process of connecting sintered parts with other steel structures

[0004] In order to solve these problems, many practical technologies have been proposed, such as A Costa, R M Miranda, and L. Quintino proposed an automatic welding technology for laser welding: Materials Behavior in Laser Welding of Hardmetals to Steel, Materials and Manufacturing Processes, 2006, 21 (5), 459-465. The use of laser welding method for the connection of cemented carbide and steel solves the problem that the connection of cemented carbide and steel depends on the heating and size limitations in the furnace, making the production of cemented carbide and steel connection enter It is possible to provide a possibility in the stage of industrial automation, and a method of controlling the quality of the weld seam by controlling the heat input and the laser action position is proposed, which can effectively suppress the interface reaction and improve the strength of the weld seam. However, due to the large thermal expansion of cemented carbide and steel Due to the difference in coefficient and the absence of a certain intermediate layer of buffer material in the welding process, the tungsten carbide in the heat-affected zone on the cemented carbide side of the joint often dissolves in a large area, which reduces the original performance of the cemented carbide

Images