Additive manufacturing method for heterogeneous steel pipe joints

Abstract

The invention relates to the field of laser additive manufacturing, in particular to an additive manufacturing method for heterogeneous steel pipe joints. The direct welding and manufacturing of existing heterogeneous steel pipe joints have problems such as low weld fusion surface strength, cracks in welded joints and heat affected zones, and performance degradation after long-term service. According to the additive manufacturing method for heterogeneous steel pipe joints, by adoption of the laser-coaxial powder feeding additive manufacturing technology, spherical powders of two alloys A and Bare put into two powder feeders; and the powder feeding ratio and the laser power are continuously changed during the melting process to change chemical components in a micro-zone of a molten pool, so that heterogeneous steel pipe joints with the chemical components transitioning from A to B in order are formed; the difference in physical properties, such as the expansion coefficient, of the twosides of the heterogeneous steel pipe joints is reduced; the thermal stress under high temperature and high pressure is greatly reduced; the chemical component concentration gradient on both sides ofthe heterogeneous steel pipe joints is also reduced; the interdiffusion of the alloys A and B can be inhibited; high temperature properties are improved, and the and service life is prolonged; and themethod has significant safety and economic benefits.

Description

technical field [0001] The invention relates to the field of laser additive manufacturing, in particular to an additive manufacturing method for dissimilar steel pipe joints, which are used to connect two steel pipes of different materials. Background technique [0002] The use of different heat-resistant alloy heat exchange tubes for high-temperature and high-pressure boilers in different heat load areas requires the use of a large number of dissimilar steel pipe joints. At present, the widely used dissimilar steel pipe joints are directly welded together by two different metal pipes through a welding process. The filler metal at the welding position of the metal pipe adopts one of the base materials, such as the butt welding of TP347H and S30432 materials, using the S30432 electrode; or using other materials such as the butt welding of T91 and S30432 materials, using the ERNiCr-3 electrode. This welding process will produce a layer of interface with different properties an...

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved and the technical task proposed by the present invention are to solve the problems of low welding fusion surface strength, cracks in the weld seam and heat-affected zone, and performance degradation after long-term service in the direct welding of existing dissimilar steel pipe joints. The present invention provides a An additive manufacturing method for dissimilar steel pipe joints, the steel pipe joints made by this manufacturing method are well melted at the docking position, the components of the two materials transition in an orderly manner, and the difference in physical properties such as expansion coefficients on both sides of the steel pipe joints is small. The stress is greatly reduced; the concentration gradient of chemical components on both sides of the steel pipe joint is low, which is beneficial to inhibit the interdiffusion of dissimilar alloys, improve the mechanical properties of the steel pipe joint after high temperature aging, and prolong the service life of the steel pipe joint, which has significant safety and economic benefits

Images