Numerical investigation of residual stresses, distortion and microstructure evolution in multi-pass welded steel components

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Tezin Türü: Doktora

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Rektörlük, Rektörlük, Türkiye

Tezin Onay Tarihi: 2016

Öğrenci: NURIYA GARIPOVA

Eş Danışman: CEMİL HAKAN GÜR, CANER BATIGÜN

Özet:

Formation of residual stresses, distortion and microstructure evolution in multi-pass welding and surfacing welding on pipeline HSLA steels were numerically investigated. A procedure for three-dimensional finite element analysis of temperature field, stress-strain state and phase changes in weldments was developed by using ESI SYSWELD & VISUAL WELD software. Numerical results were verified by comparisons with the results of various tests and measurements, such as molten pool profile calibration, microstructure investigation, hardness measurement, residual stress measurement by XRD. Influences of the subsequent weld passes, the interpass temperature, and the unclamping temperature on the residual stress state were investigated. Subsequent weld passes accomplish partial PWHT on the previous weld passes. Higher interpass temperature decreases residual stresses, but shows greater effect on distortion. Besides, the effects of weld pass sequence and welding direction in surfacing welding were studied for three different cases. It was observed that the most uneven weld deposition mode results in more uniform residual stress field and deformation.