Numerical Simulation and Experimental Verification of Residual Stress in the Welded Joints of Weldolet-Branch Pipe Dissimilar Steels.

Chunliang Mai,Xue Hu,Lixin Zhang,Bao Song,Xiongfei Zheng

doi:10.3390/ma15031044

Chunliang Mai, Xue Hu + Show 3 more

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https://doi.org/10.3390/ma15031044

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Abstract

It is well known that welding dissimilar metals can play the advantages and characteristics of those different metals, but it is easy to encounter some problems. In this paper, the thermomechanical behavior of the weldolet–branch dissimilar steel joints in different welding cases is analyzed by establishing a three-dimensional finite element model, and the predicted thermal cycling and residual stresses are verified using experimental tools. The results show that the high temperature area and the heat affected zone on the side of the branch pipe are larger, and there is a large stress gradient at the fusion line on both sides of the weld. Too high or too low temperature between welding layers will cause large residual stress, thus, 200 °C is more suitable for the welding of weldolet–branch joints. The residual stresses of path-1, path-2 and path-3 have similar distributions at 0° and 180° sections, and the circumferential and axial residual stresses on the inner surface are larger than those on the outer surface. The residual stress on the inner and outer surfaces of path-3 is smaller than that of path-1 and path-2 at the 90° and 270° sections as a whole, and the residual stress at the 90° section reaches the minimum.

Highlights

As a new type of reinforcing receiver, the weldolet is widely used in pipeline systems of chemical plants, thermal power plants and nuclear power plants
The surrou ing points of the butt joint of the weldolet and the branch pipe are fixed by spot weld The rust, oil and other impurities near the groove are cleaned up before welding. experimental process was a two‐layer, two‐pass weld, and the welding sequence w single‐pass straight‐through type with gas tungsten arc welding (GTAW) priming and SWAM filler capping. shielding gas is pure argon, and the welding parameters of the different welding chan are shown in TablFeix1tu.reThe workpiece needs to be preheated before welding, and the heaating temperature and the interlayerbtemperature are kept the same
The purpose of this study is to investigate the influence of the interlayer temperature and welding sequence on the residual stress distribution of dissimilar steel joints

Summary

Introduction

As a new type of reinforcing receiver, the weldolet is widely used in pipeline systems of chemical plants, thermal power plants and nuclear power plants. The weldolet can directly replace the traditionally used branch pipe connections, such as reducer tees and reinforced pipe sections, with higher safety and economy. It is especially used more frequently in high temperature, high pressure and even ultra-high pressure and subcritical pipelines [1,2,3,4,5]. The realization of the interconnection of dissimilar materials can combine the advantages of these materials and compensate for the defects of different materials themselves, which, to some extent, effectively meets the production requirements [8,9,10]

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