Most of the welding of steel is fabrication and repair welding. Following a welding operation, the cooling and contracting of the weld metal cause stresses to be set up in the weld and in adjacent parts of the weldment which results to cracking and embrittlement in steel welds.The best way to minimize above difficulties is to reduce the heating and cooling rate of the parent metal and HAZ. Pre heating and/or Post heating have been widely employed in welding operation for preventing cold cracking. This paper presents the effect of preheating and/or PWHT on maximum HAZ hardness, cold cracking susceptibility and residual stresses of various hardened steel types.