A Method for Analyzing and Eliminating Hidden Defects of Welded Pipes

Abstract

The invention discloses a numerical calculation method for analyzing and eliminating hidden defects of welded pipes. Including: setting the geometric parameters in the overall model of high-frequency welding and intermediate frequency heat treatment of welded pipes as variables, and assigning values ​​to the set variables; using Hypermesh to establish the overall model of welding and heat treatment, and performing grid optimization; generating models into ANSYS, setting high-frequency welding, intermediate frequency Heat treatment boundary conditions, initial conditions, thermal physical environment and electromagnetic physical environment files; electromagnetic field and temperature field after intermediate frequency heat treatment; geometric model and grid are imported into SYSWELD, and boundary conditions and physical environment are set according to the material characteristics of the tube blank, and extracted from ANSYS Import the temperature field data into SYSWELD as the initial condition; calculate the residual stress distribution of the welded pipe after it is air-cooled to room temperature; adjust the distance between heat treatment internal coil 1 and internal coil 2 according to the residual stress calculation results; repeat the above steps to calculate the residual stress distribution of the welded pipe after the distance is changed . This method is beneficial to eliminate hidden defects of welded pipes.

Description

technical field [0001] The invention relates to the field of welding heat treatment, in particular to a method for analyzing and eliminating hidden defects of welded pipes. Background technique [0002] During high-frequency straight seam welding of welded pipes, the induction coil is loaded with high-frequency current, and the high-frequency current energy is concentrated on the V-shaped corner area at the edge of the weld by using the skin effect and proximity effect, and the edge of the plate is instantly heated from room temperature to the welding temperature. High-frequency resistance welding, electromagnetic heating energy is concentrated, although the heating surface is small, the thermal gradient is large; the local intermediate frequency heat treatment of the weld is carried out on the basis of high-frequency welding, and the welding waste heat in online production is used. However, the superposition effect of high and medium frequency heating in the weld area of ​​...

AI Technical Summary

Problems solved by technology

Among them, the targeting of intermediate frequency heat treatment is the direct cause of the heating blind zone and overheating zone becoming the high incidence of welding quality defects

This kind of welding quality defect is different from the defects of welding cracks, slag inclusions, pores and weld appearance detected by conventional flaw detection. The low toughness, high hardness, large residual stress, and poor stability of comprehensive mechanical properties in some areas have buried a large safety hazard for welded pipes in harsh conditions, so they are called hidden defects.

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