The Influence of Microstructure Evolution in Thick Plate 9%Ni Steel Submerged Arc Welding Joint on Fracture Toughness Properties.

Autor: Li, Jiahui, Li, Yipeng, Liu, Dan, Ding, Yuming, Cui, Haichao, Tang, Xinhua, Lu, Fenggui
Předmět:
Zdroj: Journal of Materials Engineering & Performance; Oct2024, Vol. 33 Issue 19, p10081-10094, 14p
Abstrakt: The 45 mm thick plate of 9% Ni steel was successfully butt welded with NiCrMo-4 filler metal adopting the submerged arc welding (SAW) via a multi-layer and multi-pass process. After welding, the weld joints were tested in cryogenic and room temperature, respectively, to reveal the influence of microstructure evolution on fracture toughness. The microstructure of the heat-affected zone (HAZ) was characterized by reversed austenite and tempered martensite like the base metal (BM) after post-weld heat treatment, and the weld metal (WM) was presented by austenite in the form of layered columnar grain region (CGR) and fine equiaxed grain region (FGR). With the decrease in temperature, most of the reversed austenite in 9%Ni steel transformed into martensite, resulting in the plastic deformation ability of 9%Ni steel decreased significantly. Moreover, many microvoids formed in WM during the cryogenic fracture process due to the strength mismatch between precipitates and austenite. Compared to FGR, larger and more densely distributed microvoids in CGR were more likely to aggregate into macrocracks, making CGR the weak region in WM at cryogenic temperature. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index