Effect of welding heat input on microstructure and impact toughness in CGHAZ of X100Q steel

The coarse-grained heat-affected zones (CGHAZs) of X100Q steel were reproduced via simulating their welding thermal cycles with the varying heat input ( E j ) from 10 to 55 kJ/cm in Gleeble3500 system. The microstructures were characterized, and the impact toughness was estimated from each simulated...

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Bibliographic Details
Published in:Journal of iron and steel research, international international, 2019-06, Vol.26 (6), p.637-646
Main Authors: Wang, Hui-bin, Wang, Fei-long, Shi, Gen-hao, Sun, Yu, Liu, Jiang-cheng, Wang, Qing-feng, Zhang, Fu-cheng
Format: Article
Language:English
Subjects:
Applied and Technical Physics
Engineering
Machines
Manufacturing
Materials Engineering
Materials Science
Metallic Materials
Original Paper
Physical Chemistry
Processes
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Summary:The coarse-grained heat-affected zones (CGHAZs) of X100Q steel were reproduced via simulating their welding thermal cycles with the varying heat input ( E j ) from 10 to 55 kJ/cm in Gleeble3500 system. The microstructures were characterized, and the impact toughness was estimated from each simulated sample. The results indicate that the microstructure in each simulated CGHAZ was primarily constituted of lath-like bainite. With the decreased heat input and accordingly the lowered A r3 (the onset temperature for this transition), the prior austenite grain and the bainitic packet/block/lath substructure were refined remarkably, and the impact toughness was enhanced due to the microstructure refinement. The bainitic packet was the microstructural unit most effectively controlling the impact properties in CGHAZ of X100Q steel, due to their close correlation with the 50% fracture appearance transition temperatures, their size equivalent to the cleavage facet and their boundaries impeding the crack propagation.
ISSN:1006-706X
2210-3988
DOI:10.1007/s42243-019-00271-5