Characteristics of Welding Crack Defects and Failure Mode in Resistance Spot Welding of DP780 Steel

The mechanical properties of welded joints in resistance spot welding of DP780 steel were tested, and three different types of welding cracks in welded joints were investigated by optical microscopy, scanning electron microscopy and electron back-scattered diffraction. Finally, the failure mode of t...

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Bibliographic Details
Published inJournal of iron and steel research, international Vol. 23; no. 10; pp. 1104 - 1110
Main Authors WANG, Xiao-pei, ZHANG, Yong-qiang, JU, Jian-bin, ZHANG, Jian-qiang, YANG, Jian-wei
Format Journal Article
LanguageEnglish
Published Singapore Elsevier Ltd 01.10.2016
Springer Singapore
Subjects
Applied and Technical Physics
crack defect
DP780 steel
Engineering
failure mode
Machines
Manufacturing
Material
Materials Engineering
Materials Science
mechanical property
Metallic Materials
Physical Chemistry
Processes
resistance spot welding
resistance spot welding
crack defect
mechanical property
failure mode
DP780 steel
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Summary:The mechanical properties of welded joints in resistance spot welding of DP780 steel were tested, and three different types of welding cracks in welded joints were investigated by optical microscopy, scanning electron microscopy and electron back-scattered diffraction. Finally, the failure mode of the welded joints in shear tensile test was discussed. It is found the shear tensile strength of welded joints can be greatly improved by adding preheating current or tempering current. The surface crack in welded joint is intergranular fracture, while the inner crack in welded joint is transgranular fracture, and the surface crack on the edge of the electrode imprint can be improved by adding preheating current or tempering current. The traditional failure mode criterion advised by American Welding Society is no longer suitable for DP780 spot welds and the critical nugget size suggested by Pouranvari is overestimated.
Bibliography:resistance spot welding; mechanical property; crack defect; failure mode; DP780 steel
11-3678/TF
The mechanical properties of welded joints in resistance spot welding of DP780 steel were tested,and three different types of welding cracks in welded joints were investigated by optical microscopy,scanning electron microscopy and electron back-scattered diffraction.Finally,the failure mode of the welded joints in shear tensile test was discussed.It is found the shear tensile strength of welded joints can be greatly improved by adding preheating current or tempering current.The surface crack in welded joint is intergranular fracture,while the inner crack in welded joint is transgranular fracture,and the surface crack on the edge of the electrode imprint can be improved by adding preheating current or tempering current.The traditional failure mode criterion advised by American Welding Society is no longer suitable for DP780 spot welds and the critical nugget size suggested by Pouranvari is overestimated.
ISSN:1006-706X
2210-3988
DOI:10.1016/S1006-706X(16)30163-7