Manufacturing Technology 2018, 18(3):369-371 | DOI: 10.21062/ujep/107.2018/a/1213-2489/MT/18/3/369

Comparison of Residual Stress in High Strength Steel Sample before and after Laser Welding

Mária Blatnická, Michal Šajgalík, Milan Sága, Miroslav Blatnický

Faculty of Mechanical Engineering, University of Žilina. Univerzitná 8215/1, 010 26 Žilina. Slovakia

The paper deals with the evaluation of residual stress in high strength steel sample measured by x-ray method before and after laser welding. Data were collected and processed in program Matlab, where surfaces of stress distribution in the sample were created. Polynomial functions were fit to the data to achieve smoother curves and a better understanding of results. Finally, results of residual stress in the welded sample were compared to those in the non-welded sample for determining the effect of welding on residual stress. Nowadays, the use of high strength steels is being developed, yet their use is sometimes limited by their fatigue critical welds. One common problem associated with welding is the formation of residual stress. Heating, melting and cooling of the weld and nonuniform temperature distribution are causing plastic thermal strain formation, which results in permanent deformation and residual stress near the weld and its heat-affected zone and can be high enough to cause cracking without any applied loads. The welding-induced tensile residual stresses have a harmful effect on fatigue lifetime of structures, corrosion resistance and other mechanical properties. On the other hand, compressive residual stress can improve the fatigue resistance of the material.

Keywords: residual stress, laser welding, X-ray method, high strength steel Domex

Published: June 1, 2018  Show citation