Finite Element Analysis on Residual Stresses Occur in Heat Affected Zone (HAZ) of the Carbon Steel Welded Pipe

This dissertation presents the Finite Element Analysis (FEA) on the residual stresses occur in Heat Affected Zone (HAZ) of Carbon Steel Welded pipe. Residual Stresses are known to influence the mechanical properties such as creep or fatigue life of base metal. The uncontrolled amount of residual stresses can lead to serious problem in the future. The stress gradient near the fusion zone is higher than any other location in the surrounding area. This is attributed as one of the significant reasons for the development of cold cracks at the fusion zone in the high strength steel. In order to avoid such welding cracks, the residual stresses in the weld joint have to be minimized by controlling the heat input. Residual stresses are very difficult to be measured since there is a lot of complex governing equation need to be solved in order to get the result but the result is not the exact solutions. The objective of this analysis is to obtain the amount of residual stresses and its distribution at the Heat Affected Zone (HAZ) due to thermal load in Carbon Steel welded pipe. The method that being used is the Finite Element method using ANSYS Software which is a numerical procedure that can be used to obtain solution of engineering problems involving stress analysis, heat transfer, electromagnetism, and fluid flow. Welding method used is the Shield Metal Arc Welding (SMAW). The maximum stress intensity showed by the contour plot was 881 MPa. The total mechanical strain has the maximum value of 0.004769 m/m. The distortion showed that the maximum value was 0.001604m and this was seen on all degree of freedom. From the normal weld heat input that suggested by Welding Procedure Specification (WPS), the maximum temperature was 1944K. From the thermal and structural analysis, the stresses value was analyzed to see the significant of residual stresses on the HAZ of the welded pipe. As a conclusion, the more heat applied during the welding of the Carbon Steel welded pipe, the value of residual stresses was increased.