TY - JOUR
T1 - Ductile-to-brittle transition in tensile failure due to shear-affected zone with a stress-concentration source
T2 - a comparative study on punched-plate tensile-failure characteristics of precipitation-hardened and dual-phase steels
AU - Hamada, Shigeru
AU - Zhang, Jiwang
AU - Zhang, Kejin
AU - Koyama, Motomichi
AU - Tsuchiyama, Toshihiro
AU - Yokoi, Tatsuo
AU - Noguchi, Hiroshi
N1 - Publisher Copyright:
© 2018, Springer Nature B.V.
PY - 2018/8/1
Y1 - 2018/8/1
N2 - The effect of shear-affected zone (SAZ), with a stress-concentration source induced by the punching process, on tensile properties was investigated. Tests using honed specimens (which have the same shapes and stress-concentration without any SAZ) and smooth specimens were conducted to compare the effect with that of the punched specimens. Dual-phase steel, which has a high work-hardening ability and low yield strength, and precipitation-hardened steel, which has a low work-hardening ability and high yield strength, were used in the tests. Materials with two tensile strength grades were prepared from both types of steel. Only the precipitation-hardened steel with higher strength grade punched specimen showed a brittle fracture with extremely short fracture-elongation, whereas the other specimens showed a ductile fracture. The fracture surface analysis revealed that cracks initiated in the maximum shear stress plane of the SAZ under tensile loading at first. We call the crack “shear crack.” The steel which showed brittle fracture used in this study easily exhibited plastic-strain localization compared with the other steels. If the shear crack is sharp, then the transition from ductile to brittle failure tends to occur. Furthermore, the strength characteristics of the punched specimen depend on the crack length dependency of the strength resistance and the failure phenomenon of the original material.
AB - The effect of shear-affected zone (SAZ), with a stress-concentration source induced by the punching process, on tensile properties was investigated. Tests using honed specimens (which have the same shapes and stress-concentration without any SAZ) and smooth specimens were conducted to compare the effect with that of the punched specimens. Dual-phase steel, which has a high work-hardening ability and low yield strength, and precipitation-hardened steel, which has a low work-hardening ability and high yield strength, were used in the tests. Materials with two tensile strength grades were prepared from both types of steel. Only the precipitation-hardened steel with higher strength grade punched specimen showed a brittle fracture with extremely short fracture-elongation, whereas the other specimens showed a ductile fracture. The fracture surface analysis revealed that cracks initiated in the maximum shear stress plane of the SAZ under tensile loading at first. We call the crack “shear crack.” The steel which showed brittle fracture used in this study easily exhibited plastic-strain localization compared with the other steels. If the shear crack is sharp, then the transition from ductile to brittle failure tends to occur. Furthermore, the strength characteristics of the punched specimen depend on the crack length dependency of the strength resistance and the failure phenomenon of the original material.
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U2 - 10.1007/s10704-018-0304-9
DO - 10.1007/s10704-018-0304-9
M3 - Article
AN - SCOPUS:85048450643
SN - 0376-9429
VL - 212
SP - 237
EP - 248
JO - International Journal of Fracture
JF - International Journal of Fracture
IS - 2
ER -