TY - JOUR
T1 - Microstructure and mechanical properties of dissimilar NiTi and 304 stainless steel joints produced by ultrasonic welding
AU - Ao, S. S.
AU - Cheng, M. P.
AU - Zhang, Wenyi
AU - Oliveira, João Pedro
AU - Manladan, S. M.
AU - Zeng, Zhi
AU - Luo, Zhen
N1 - (No. U1933129)
(No. 18JCQNJC04100,
No. 19JCZDJC39000
No. 19YFFCYS00090
UID/00667/2020
PY - 2022/4
Y1 - 2022/4
N2 - Superelastic NiTi alloy and 304 stainless steel (304 SS) were joined with a Cu interlayer by ultrasonic spot welding (USW) using different welding energy inputs. The surface morphology, interfacial microstructure, mechanical properties, and fracture mechanisms of the dissimilar NiTi/304 SS USWed joints were studied. The results showed that the surface oxidation intensified with increasing ultrasonic welding energy due to mutual rubbing between tools and sheets. The weld interface microstructure exhibited voids or unbonded zones at low energy inputs, while an intimate contact was established at the joining interface when applying a higher energy input of 750 J. With increasing energy input to 750 J, the weld interface shows two interfaces due to the behavior of plastic flow of Cu interlayer. The lap-shear load of the joints first increased, achieving a maximum value of ∼690 N at an energy input of 750 J, and then decreased with further increase in welding energy. Interfacial failure was observed at NiTi/Cu interface at all energy inputs, and no intermetallic compounds were found on the fracture surfaces of both the NiTi/Cu and Cu/304 SS interfaces.
AB - Superelastic NiTi alloy and 304 stainless steel (304 SS) were joined with a Cu interlayer by ultrasonic spot welding (USW) using different welding energy inputs. The surface morphology, interfacial microstructure, mechanical properties, and fracture mechanisms of the dissimilar NiTi/304 SS USWed joints were studied. The results showed that the surface oxidation intensified with increasing ultrasonic welding energy due to mutual rubbing between tools and sheets. The weld interface microstructure exhibited voids or unbonded zones at low energy inputs, while an intimate contact was established at the joining interface when applying a higher energy input of 750 J. With increasing energy input to 750 J, the weld interface shows two interfaces due to the behavior of plastic flow of Cu interlayer. The lap-shear load of the joints first increased, achieving a maximum value of ∼690 N at an energy input of 750 J, and then decreased with further increase in welding energy. Interfacial failure was observed at NiTi/Cu interface at all energy inputs, and no intermetallic compounds were found on the fracture surfaces of both the NiTi/Cu and Cu/304 SS interfaces.
KW - 304 stainless steel
KW - Interlayer
KW - Intermetallic compounds
KW - NiTi alloys
KW - Ultrasonic spot welding
UR - http://www.scopus.com/inward/record.url?scp=85122658235&partnerID=8YFLogxK
U2 - 10.1016/j.ultras.2022.106684
DO - 10.1016/j.ultras.2022.106684
M3 - Article
AN - SCOPUS:85122658235
SN - 0041-624X
VL - 121
JO - Ultrasonics
JF - Ultrasonics
M1 - 106684
ER -