Numerical simulation of slit type cracking test for 9%Ni steel

With SYSWELD software, the temperature and stress field of 9% Ni steel Y-slit weldments with different preheat temperatures were simulated by applying double-ellipsoid heat source.Distribution laws of welding temperature and stress field were studied.Effects of preheat temperature on welding heat cycles and residual stress were analyzed.Results show that with increasing preheat temperature, cooling rate decreases facilitates escaping of hydrogen and self-tempering of martensite, the average stress level and cold-cracking susceptibility of the weldments increase, so high preheat temperature shall be avoided for 9%Ni steel welding.