A new test method named “Trapezoidal hot” cracking test was developed to evaluate solidification cracking susceptibility of stainless steel during laser welding. The new test method was used to obtain the solidification cracking directly, and the solidification cracking susceptibility could be evaluated by the solidification cracking rate, defined as the ratio of the solidification cracking length to the weld bead length under certain conditions. The results show that with the increase in the solidification cracking rate, the solidification cracking susceptibility of SUS310 stainless steel was much higher than that of SUS316 and SUS304 stainless steels during laser welding (at a welding speed of 1.0 m/min) because a fully austenite structure appeared in the weld joint of the former steel, while the others were ferrite and austenitic mixed structures during solidification. Besides, with an increase in welding speed from 1.0 to 2.0 m/min during laser welding, the solidification cracking susceptibility of SUS310 stainless steel decreased slightly; however, there was a tendency towards an increase in the solidification cracking susceptibility of SUS304 stainless steel due to the decrease in the amount of ferrite under a higher cooling rate.

In order to prevent the lead-bismuth eutectic (LBE) corrosion of stainless-steel components used in nuclear reactors, the FeCrAlTiC-xY₂O₃ coatings were prepared on 304 stainless steel (304SS) by laser cladding. After adding Y₂O₃, Y₂TiO₅ and Y₂Ti₂O₇ formed, which have a combined strengthening effect on improving hardness. The 0.2 wt.% Y₂O₃ coating showed the highest hardness as ~489 HV. In the 400 °C wear test, the weight loss of coating samples was less than ~5.2 mg, while the weight loss of 304SS samples was ~35.5 mg. The 0 wt.% Y₂O₃ coating showed the highest wear resistance, indicating that adding Y₂O₃ could result in the decrease of wear resistance. The LBE corrosion behaviors of coatings at 500 °C were investigated. The results showed that a uniform and dense oxide scale with a low growth rate was obtained on the coating surface, and no penetration of LBE into the coating was observed. After 1000 h of corrosion, the oxide scale of coatings grew to merely a ~0.3 μm thickness. The corrosion resistance mechanism of the coating in oxygen-saturated LBE at 500 °C was proposed based on experimental results along with a thermodynamic and kinetic analysis.

The modified Zn interlayer was introduced to realise the tungsten inert gas (TIG) arc lap welding of DP780 steel (upper plate) and 6061 aluminum alloy (lower plate). The tensile shear force of the joint could be increased to more than 150 N/mm by introducing a modified Zn interlayer with a large hole diameter and hole spacing. The large hole diameter and spacing can regulate the heat conduction effect of the steel–aluminum interface, increase the welding penetration and width of the aluminum side and facilitate adequate metallurgical reactions. Moreover, allowing a certain amount of Zn vapour to escape promptly is beneficial, ensuring the stability of the interfacial melting pool and achieving high-quality welded joints.