Chuan PAN
,
Zhengbang LI
,
Zhiling TIAN
,
Dongtu LIANG
,
Lijie QIAO
,
Wuyang CHU
材料科学技术（英文）
For 308L and 347L weld metals of austenitc stainless steels (ASS), hydrogen induced cracking (HIC) occurred during dynamically charging under constant load. The threshold stress intensity for HIC, KIH, decreased linearly with the logarithm of the concentration of diffusible hydrogen C0 in the weld metals and the rolled plate of type 304L ASS, i.e., KIH=85.2-10.7ln C0 (308L),KIH=76.1-9.3ln C0(347L), and KIH=91.7-10.1ln C0(304L). The fracture mode for HIC in the three type of ASS changed from ductile to brittle with the decrease in the applied stress intensity KI or/and the increase in C0. The boundary line between ductile and brittle fracture surfaces was KI-54+25exp(-C 0/153)=0.
关键词:
Austenitic stainless steel
,
null
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Xudong ZHANG
,
Wuzhu CHEN
,
Cheng WANG
,
Lin ZHAO
,
Yun PENG
,
Zhiling TIAN
材料科学技术（英文）
3 mm thick 400 MPa grade ultrafine grained ferritic steel plates were bead-on-plate welded by CO¬2 laser with heat input of 120~480 J/mm. The microstructures of the weld metal mainly consist of bainite, which form is lower bainite plates or polygonal ferrite containing quantities of dispersed cementite particles, mixed with a few of low carbon martensite laths or ferrite, depending on the heat input. The hardness and the tensile strength of the weld metal are higher than those of the base metal, and monotonously increase as the heat input decreases. No softened zone exists in heat affected zone (HAZ). Compared with the base metal, although the grains of laser weld are much larger, the toughness of the weld metal is higher within a large range of heat input. Furthermore, as the heat input increases, the toughness of the weld metal rises to a maximum value, at which point the percentage of lower bainite is the highest, and then drops.
关键词:
Laser welding
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null
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null
,
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