Effect Of Accelerating Cooling On Microstructure And Toughness Of HAZ Of X70 Pipeline Steel
加速冷却对X70钢热影响区组织与韧性的影响

Based on the effect of accelerating cooling on the microstructure and properties of thermo-mechanical control process (TMCP) steel, we proposed to adopt this method for improvement of heat affect zone (HAZ) toughness of X70 pipeline steel. The results of simulated experiment and actual weldment indicate that at appropriate accelerating cooling rate the M-A constituent in HAZ is reduced obviously in amount and replaced by tough austenite films. Coarse bainitic sheaves were obtained when jetting water directly to the sample and the toughness is not improved. Accelerating cooling with appropriate cooling rate is a simple and efficient method to improve the HAZ toughness.