Method of Controlling Crack Formation in Heat-Affected Zone of Nickel-based Alloy Multilayer Laser Filler Welding

Abstract

The invention discloses a method for controlling liquefied crack formation in heat affected zones in nickel-based alloy laser multi-layer filler wire welding. The method is mainly suitable for the welding process of welding and repair welding of nickel-based alloy laser filler wires with the thickness ranging from 3 mm to 12 mm. According to the method, the main principle is that joint stress distribution is changed, and the high-temperature dwell time of the heat affected zones of the overlapped positions is shortened, so that the crack formation rate is lowered. The welding method mainly comprises the following steps that firstly, the appropriate laser welding defocusing amount is determined, so that the fusion line of the cross section of each of weld joints is in a circular arc shape or an oval arc shape; and secondly, after the primary weld joint process is completed, in the secondary welding process, the heat affected zones generated in primary welding are made to be located in weld joint regions generated in the secondary welding process, and so on, the follow-up weld joints are treated. By the adoption of the welding method, under the same condition, the crack rate is lower compared with common laser filler wire repair welding or laser filler wire thick plate welding.

Description

technical field [0001] The invention belongs to the technical field of nickel-base alloy multi-layer laser wire-fill welding, and mainly relates to a connection method for butt welding of nickel-base alloy plates less than 12 mm thick, in particular to a laser wire-fill repair welding method for nickel-base alloy casting defects. Background technique [0002] High-temperature nickel-based alloys are widely used in important large-scale components such as steam turbines, engines, turbine disks, and blades because of their good mechanical properties, good high-temperature oxidation resistance, corrosion resistance, and good thermal stability in high-temperature environments. These large components will have a certain degree of defects and damage during the casting process or in the high-temperature service environment, so they must be repaired or replaced in time, but when the damaged area is small, replacing the entire component will not only increase the cost, but also Incre...

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Problems solved by technology

[0005] The invention aims to solve the problem that cracks are prone to appear in the heat-affected zone in nickel-based alloy laser wire repair welding or butt welding. By controlling the heat input of the weld seam, the secondary heat of the heat-affected zone can be avoided, and the high-temperature residence time of the heat-affected zone can be reduced. At the same time, by controlling the laser defocus, the welding seam is controlled to be arc-shaped or elliptical, avoiding the "nail-shaped" weld seam formation that easily leads to stress concentration, changing the stress distribution of the joint, thereby reducing the formation rate of liquefaction cracks in the heat-affected zone , to provide an effective method to control the formation of liquefaction cracks in the heat-affected zone of nickel-based alloy laser wire repair welding and butt welding

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