Precipitation hardening on repeated heating in welded joints of the 1Kh2M and 1Kh2MFB

The study concerns the regularities of precipitation hardening of the metal of the weld and of the weld-adjacent zone of 1Kh2M and 1Kh2MFB steels in reheating to temperatures of 550, 600 and 650 deg C. It is shown that the degree of strengthening and latter stability in welds of 1Kh2MFB steel are much higher than those in 1Kh2M steel. This is explained by a higher thermal stability of niobium and vanadium carbides precipitating on decomposition from the solid solution as compared to that of chromium and molybdenum carbides. The obtained temperature vs. time dependences can be helpful in selecting heat treatment conditions ensuring the required final hardness of welds of the above steels