Microstructure and Texture Evolution in the Welded Semi-Austenitic PH Steel after the Heat Treatment

The aim of this study was to reveal the influence of the heat treatment after welding of 17-7PH (X7CrNiAl17-7) steel on the microstructure evolution and the texture of the welds.Microstructure investigation carried out by light microscopy and transmission electron microscopy showed that the austenite and δ ferrite coexist in as-welded condition.Annealing at the temperature range between 400 • C and 620 • C after welding causes small changes in the microstructure and the hardness of the welds increases.Heat treatment at 760 • C for 1 h resulted in the partial destabilization of the austenite.Aging after destabilization leads to tempering of the martensite: first the hardness increases and then decreases.The maximum hardness is observed when the ageing temperature reaches 510 • C. XRD studies confirmed the presence of the two phases: δ ferrite and austenite.Annealing at 400 • C/1 h and 550 • C/1 h results in changes of the intensities for individual peaks derived from austenite and ferrite.The calculated ratios of peak intensity were compared with the intensities of the reference sample.The differences in intensities suggested strong texture of the material.