Residual stress in welded high-strength steels and their correlation with microstructure

Abstract

Steel is the most important engineering metal, and with improvements in the manufacturing of higher-strength steel, its use is increasing. Accordingly, understanding problems relating to high-strength is of utmost importance. This study investigates the correlation between residual stress and microstructure in welded high-strength steels. For this purpose, a range of tests has been conducted on two samples of dissimilarly welded steels, namely Domex 500 MC D and Strenx 700 MC PLUS, in two different plate thicknesses, with the 6 mm thick plate being welded with a single run and the 8 mm thick plate with a double run of robotised gas metal arc welding. The tests included residual stress measurement, hardness measurements, and scanning electron microscopy of the microstructure. The results showed different residual stress profiles for the different steel grades and thicknesses. These differences are explained by differences in the chemical and microstructural compositions of the two steels, and by the different heat cycles of the different welds.