Abstract：The effect of T8/5 time on the coarse-grained microstructure and properties in heat affected zone of X80 pipeline steel was investigated by Gleeble 3500 thermal simulator with four T8/5 time ranged from 21 to 40 s. The Charpy V-Notch impact toughness on a coarse grained region was measured，and the microstructure and the fracture morphology after the impact toughness measurement was analyzed. The results showed that the coarse-grained heat affected zone with T8/5 of 21 s exhibits excellent and steady low temperature Charpy V-Notch impact toughness. The low temperature impact toughness decreases as the T8/5 time increases from 21 to 40 s，and the fracture mechanisms is transformed from ductile fracture to brittle rupture. The impact fracture model changes from a partly ductile fracture to a totally brittle fracture as well at －20 ℃. Prolonging the T8/5 time can promote the formation of long strip M/A constituents in the coarse-grained heat affected zone and the space between the bainitic laths.
张清清，章传国，郑磊. T8/5时间对X80管线钢热影响区组织和韧性的影响[J]. 中国冶金, 2017, 27(4): 26-31.
ZHANG Qing-qing，ZHANG Chuan-guo，ZHENG Lei. Effect of T8/5 time on microstructure and toughness in heat affected zone of X80 pipeline steel. China Metallurgy, 2017, 27(4): 26-31.
2017, Vol. 27 
