Abstract：Heavy steel plates (max thickness， 80 mm) for offshore platform with yield-strength greater than 500 MPa have been produced by thermomechanically controlled process (TMCP). Continuous cooling transformation in the simulated coarse-grained heat-affected zone (CGHAZ) was investigated. The influence of heat input[E]on the microstructure and mechanical properties of the CGHAZ with and without second reheating peak temperature[(t2p)]was studied by means of metallographic analysis， hardness testing， instrumented impact testing and electron backscatter diffraction (EBSD). The microstructure of the CGHAZ changes from lath-like Bainite (LB) to granular Bainite (GB) as[E]increases， resulting in decreased hardness， impact energy， and the fraction of large-angle grain boundaries (＞15°). The predominant microstructure of the CGHAZ is refined LB when[E]is lower than 50 kJ/cm. Coarsened martensite-anstenite constituents (MA) are formed in the intercritically (reheatedCGHAZ) with[t2p]at 750 ℃. This leads to decreased impact toughness showing brittle fracture regardless off the variation of heat input. When[E]is smaller than 50 kJ/cm and[t2p]is higher than 850 ℃， the fraction of high angle grain boundaries increases and the impact toughness is largely improved showing ductile fracture.
收稿日期: 2014-12-06
出版日期: 2015-09-08
引用本文:
陈焕德，刘东升. TMCP特厚E500钢板模拟焊接热影响区的组织与性能[J]. 钢铁, 2015, 50(9): 87-91.
CHEN Huan-de，LIU Dong-sheng. Microstructure and properties of simulated heat affected zone of TMCP processed E500 heavy plate steel for offshore platform. Iron and Steel, 2015, 50(9): 87-91.
2015, Vol. 50 
