DAI Guangming, JIANG Guoyan, YIN Dongyang, et al.Analysis and Improvement of the Cracking of Bending Test by Electrode Arc Welding based on 9%Ni steel sheet[J].Electric Welding Machine, 2023, 53(5): 70-76.
DAI Guangming, JIANG Guoyan, YIN Dongyang, et al.Analysis and Improvement of the Cracking of Bending Test by Electrode Arc Welding based on 9%Ni steel sheet[J].Electric Welding Machine, 2023, 53(5): 70-76. DOI: 10.7512/j.issn.1001-2303.2023.05.10.
Analysis and Improvement of the Cracking of Bending Test by Electrode Arc Welding based on 9%Ni steel sheet
The ,w,(Ni) =60 nickel-base type (Ni-Cr-Mo) series alloy is widely used for LNG (liquefied natural gas) Marine vessels 9%Ni steel welding. For thin plate (thickness less than 5 mm) welding, the transverse bending test is easy to produce cracks. The research on this problem is lacking. In this paper, this study would investigate the reasons for the easy occurrence of unqualified cracking (bend surface crack length more than 3 mm),through the combination of finite element analysis and process test the X7Ni9 steel sheet welded by manual (ENiCrMo-6) arc welding process. The results show that the main reason of bending cracking is that the base material and welding material are heterogeneous materials. The yield strength varies greatly. When the test plate thickness is too thin, the weld metal is overstretched and forced cracking beyond 4t requirement of the standard during the lateral bending test, which distorts the test results. The weld orifice defect are easy to occur on root weld by manual (ENiCrMo-6) arc welding process with poor weld formation under combined action of.which and crack lead to the sample fracture. The process improvement measures: increase the weld width to ensure sufficient plastic reserve when stretching, control the weld duct molding to improve the weld orifice defects; adopt longitudinal bending instead of transverse bending test. The process improvement measures are: increase the weld width to ensure sufficient plastic reserve when stretching; control the weld duct forming to improve the weld orifice defect.
WEI B C,YANG S Y,SUN X H. Quality safety and health risks of 9%Ni steel vertical weld by SMAW for LNG tank[J]. Electric Welding Machine,2020,50(08):110-117+141.
SUN X. Discussion on selection principle of 9%Ni steel welding consumable based on engineering application[J]. Welding Digest of Machinery Manufacturing,2018(04):6-16.
MIN X F,ZHAO Z H,LI Y L,et al. Effect of welding parameters on microstructure and bending properties of welded joint of 9Ni steel[J]. Electric Welding Machine,2019,49(06):41-44+49.
GUO W,CAI Y,HUA X M. Microstructure and Cryogenic Properties of Low-nickel Low Temperature Steel Joint for LNG Storage Tank[J]. Electric Welding Machine,2022,52(01):17-24.
JIA L C.Development of nickel based alloy submerged arc welding flux for LNG storage tank and research on the mechanism of welding hot crack[D].Heilongjiang:Harbin Institute of Technology,2017.
SONG B,GUO X,CHU J J,et al. Current situation of bending test standards for welded joints and study of influence factors[J]. Pressure Vessel Technology,2022,39(09):64-71+86.
王峰,房永强.试样加工质量对金属性能的影响及改进[J].山东工业术,2015(21):7.
WANG F,FANG Y Q. Influence and Improvement of Sample Processing Quality on Metal Properties[J]. Shandong Industrial Technology,2015(21):7.
MIN X F,ZHAO Z H,BAI X L,et al. Discussion on bending test method of welded joint based on 9Ni steel[J]. Electric Welding Machine,2019,49(05): 104-107.