Welded joint with excellent fatigue-resistance characteristics, and method for producing same

Abstract

Provided are: a welded joint that exhibits the effect of ultrasonic shock treatment more efficiently, and has improved fatigue-resistance characteristics; and a method for producing the joint. In thisjoint, the average hardness of the weld zone and of the heat-affected zone is 15% to 50% higher than that of the steel stock, and at the weld toe, an ultrasonic shock scar is formed which has a radius of curvature r of 1.0 to 10.0 mm at the cross-section perpendicular to the weld-line, and a thickness d of 1.0 mm or less from the surface of the steel stock.

Description

technical field [0001] The present invention relates to a welded joint excellent in fatigue resistance and a method of manufacturing the same. In particular, it relates to a welded joint capable of improving the reliability and prolonging the life of the welded structure by using it in a welded structure, and a method for manufacturing the same. Background technique [0002] Steel structures are often subject to cyclic loads during service, and it is necessary to fully consider the safety of the fatigue strength of the welded zone. [0003] Figure 6 is a schematic cross-sectional view showing an example of the welded joint 1 . The state where the steel materials 2, 2' are joined by the weld metal 3 is shown. Generally, the fatigue strength of the weld zone is significantly lower than that of the base metal. The main reasons for this are: the stress concentration at the weld toe 6, 6' is remarkable; the tensile residual stress is formed at the weld toe; Grain coarsening i...

AI Technical Summary

Problems solved by technology

[0005] However, the above-mentioned methods such as grinding, TIG trimming, and shaving and reinforcing surfacing welding have problems in that the work efficiency is poor, and the strength of the joint is reduced depending on the processing method, and the effect depends on the operator's proficiency.

In addition, shot peening, hammering, laser surface hardening, wet shot peening, or post-weld heat treatment have the problem of requiring large equipment and operating costs depending on the structure of the object to be treated.

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