Plasma spraying method for improving fatigue performance of welded structure

Abstract

The invention discloses a plasma spraying method for improving the endurance feature of welded structures in the invention, applied to a plasma spraying process in spraying coat on the surface of brazing seam, which is comprised the following steps: a. gritting blasting in the brazing seam of specimen; b. plasma spraying bound substratum on the surface of the brazing seam for 0.03mm to 0.07mm in thickness, the materials of which is selected form Ni / AL, Ni / Cr or McrALY, wherein the M is a transient metal as Fe, Ni, Co or NiCo; c. spraying plasma powder on the brazing seam surface as face coat for 0.8mm to 1.2mm in thickness. The invention improves the endurance feature of the welded structure in such a way of plasma spraying coats of a low elasticity modulus in the weld joint, with which the shape of the cross section can be improved, the stress concentration there can be lower and the endurance strength of the welded structure can be advanced; (b) comparing to the welding specimen, the endurance strength of the invented plasma spraying specimen increases 25.9 percent, while flame spraying specimen increases only 9.7 percent.

Description

technical field [0001] The invention relates to a post-treatment method for welded joints of metal materials, in particular to a plasma spraying method for improving the fatigue performance of welded structures. Background technique [0002] The ability of welded joints to withstand static loads is generally not lower than that of the base metal, but the ability to withstand alternating loads is far from that of the base metal. Therefore, some welded structural joints cause premature fatigue cracks and fail. The main reasons for the low fatigue strength of welded structures are: the sudden change of the section caused by the weld metal; the residual stress and deformation caused by local heating and uneven cooling; welding defects such as undercut and slag inclusions in the weld toe area. For the specific welding structure, some technological measures can be taken after welding to improve its fatigue strength, such as local grinding at the welding toe, shot peening, TIG weld...

AI Technical Summary

Problems solved by technology

For the specific welding structure, some technological measures can be taken after welding to improve its fatigue strength, such as local grinding at the welding toe, shot peening, TIG welding remelting, local heating, low phase transition point electrode and ultrasonic impact treatment, etc. Its purpose is to reduce stress concentration, eliminate notches or introduce compressive residual stress on the surface of the component, but the effect is not very satisfactory

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