Effect of Post Weld Heat Treatment on Microstructure and Properties of Laser Arc Hybrid Welded AH36 Ship Plates

To improve the microstructure and properties of the laser-arc hybrid welded AH36 steel plate joints, post-weld heat treatment was applied, including single high-temperature tempering and quenching+high-temperature tempering. The experimental results show that high-temperature tempering at 550℃ has no effect on the microstructure of the joint but results in a reduction in hardness. During quenching at 850℃, the joint does not achieve complete austenitization. When the quenching temperature is increased to 880℃, the joint undergoes complete austenitization and forms a large amount of martensite after quenching. After high-temperature tempering at 550℃, it transforms into tempered sorbite with good comprehensive properties. However, when the quenching temperature is further increased to 910℃, the resulting martensite is coarse, and there is a higher amount of retained austenite. When employing a quenching temperature of 880℃ followed by a high-temperature tempering at 550℃, the joint exhibited the optimal microstructure and properties. At the same time, the hardness distribution became more uniform, with an average hardness of 190 HV.