Composite welding method for preventing coarsening of base material HAZ crystal grains

Abstract

The invention discloses a composite welding method for preventing coarsening of base material HAZ crystal grains. The method includes the steps that (1) a plurality of layers of metal wires with required components are formed on a to-be-welded surface of a workpiece, namely a base material through build-up welding, so that a build-up welded layer with a certain thickness is formed, wherein the thickness of the build-up welded layer is larger than the before-welding thickness (delta); (2) after build-up welding, a required groove shape and size are machined in the build-up welded layer; and (3)filling welding is carried out through a conventional welding method to fill a groove, and the build-up welded layer with an initial thickness (alpha) is melted in the filling welding process, so that the thickness of the grooved build-up welded layer is reduced from the before-welding thickness (delta) before filling welding to the after-welding thickness (theta) after filling welding, meanwhile, a heat affected zone with the width (beta) formed by filling welding is formed on the remaining build-up welded layer with the after-welding thickness (theta), and the before-welding thickness (delta), the initial thickness (alpha) and the width (beta) satisfy the condition that delta minus alpha is lager than beta or theta is larger than beta.

Description

technical field [0001] The invention relates to the technical field of mechanical processing welding. Background technique [0002] When conventional arc welding methods and processes are used to weld materials such as fine-grained high-strength steel and ferritic stainless steel that are sensitive to heat input, due to the relatively large welding heat input, the high temperature residence time in the welding heat-affected zone (HAZ) is longer, resulting in Due to the serious grain coarsening of HAZ, the mechanical properties of joints are significantly reduced. Both theoretical research and production practice show that reducing the welding heat input is the most effective way to suppress the grain coarsening of the base metal HAZ. In comparison, grain coarsening in the weld zone is relatively easy to solve, for example, by adding grain refinement elements (Nb, Ti, B) to the weld pool, or applying ultrasonic vibration to the weld pool to effectively refine grains in the ...

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Problems solved by technology

[0002] When conventional arc welding methods and processes are used to weld materials such as fine-grained high-strength steel and ferritic stainless steel that are sensitive to heat input, due to the relatively large welding heat input, the high temperature residence time in the welding heat-affected zone (HAZ) is longer, resulting in The mechanical properties of the joint are significantly reduced due to the severe grain coarsening of the HAZ

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