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Thick-section austenitic stainless steels have widespread industrial applications, especially in nuclear power plants. The joining methods used in the nuclear industry are primarily based on arc welding processes. However, it has recently been shown that narrow gap laser welding (NGLW) can weld materials with thicknesses that are well beyond the capabilities of single pass autogenous laser welding. The heat input for NGLW is much lower than for arc welding, as are the expected levels of residual stress and distortion. This paper reports on a preliminary investigation of the through-thickness 2D residual stresses distributions, distortions, and plastic strain characteristics, for the NGLW process using material thicknesses up to 20 mm. The results are compared with those obtained with gas-tungsten arc (GTA) welding. While further work is required on thicker test pieces, preliminary results suggest that the longitudinal tensile residual stresses in NGLW joints are 30e40% lower than those for GTA welds.

Industrial trials and thermodynamic calculations are performed to investigate the effect of Al content on the evolution of non-metallic inclusions in Si-Mn deoxidized spring steel by using scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS) and FactSage thermodynamic software. Sulfide type inclusions and CaO-Al 2 O 3 -SiO 2 -MgO type complex inclusions are two major non-metallic inclusions. The effect of Al content on the evolution of CaO-Al 2 O 3 -SiO 2 -MgO system inclusions is discussed. The stability diagram of Fe-Mn-Si-Al-Mg-O system inclusions is calculated in liquid steel at 1873 K. In practice, to achieve the liquid inclusions in molten steel, both the amount of magnesium and aluminum should be considered simultaneously.

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