Bending fatigue life enhancement of NiTi alloy by pre-strain warm surface mechanical attrition treatment

Wei, Pengbo1,2; Hua, Peng1,3; Xia, Minglu1; Yan, Kai1,2; Lin, Hongyang1; Yi, Shenghui4,7; Lu, Jian4,5,6; Ren, Fuzeng2; Sun, Qingping1,3

2022-11-01

10.1016/j.actamat.2022.118269

ACTA MATERIALIA   Impact Factor & Quartile

1359-6454

1873-2453

Many structures like medical stents made of superelastic NiTi shape memory alloy (SMA) are subjected to cyclic bending loads and show a limited fatigue life due to crack nucleation and growth in the surface layers under local tensile stress. Here, we enhance the bending fatigue life of NiTi plates by pre-strain warm surface mechanical attrition treatment (pw-SMAT) where the austenite phase is directly subjected to severe plastic deformation and grain refinement without inducing phase transformation. Amorphous and grain size gradient (5-100 nm) microstructures, as well as a maximum compressive residual stress of 1093 MPa are produced in the surface layer of the NiTi plates via the pw-SMAT. The compressive residual stress notably reduces the surface tensile stress from bending. The grain size gradient layers with improved hardness and reduced hysteresis have high fatigue crack nucleation resistance, while the middle large-grained layers of the plates have high fatigue crack growth resistance. The combined effects of the gradient nanostructure and the compressive residual stress substantially increase the bending fatigue life of the NiTi plates from an original 10 3 cycles to over 1.3 x 10(4) cycles. The results open up a new route to improve the bending fatigue life of NiTi plates by heterogenous nanostructures. (C) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Shape memory alloy (SMA) Fatigue Grain refinement Residual stress Pre-strain warm surface mechanical  attrition treatment (pw-SMAT)

SCI

English

Corresponding

Hong Kong Research Grant Council (RGC)[16206119] ; National Natural Science Foundation of China[52122102] ; Shenzhen Science and Technology Innovation Committee[SGDX2019081623360564] ; Project of Hetao Shenzhen- Hong Kong Science and Technology Innovation Cooperation Zone[HZQB-KCZYB-2020083] ; Fundamental Research Program of Shenzhen[JCYJ20190809153205492]

Materials Science ; Metallurgy & Metallurgical Engineering

Materials Science, Multidisciplinary ; Metallurgy & Metallurgical Engineering

WOS:000862266600004

PERGAMON-ELSEVIER SCIENCE LTD

MATERIALS SCIENCE

Web of Science

1.Hong Kong Univ Sci & Technol, Dept Mech & Aerosp Engn, Kowloon, Clear Water Bay, Hong Kong, Peoples R China
2.Southern Univ Sci & Technol, Dept Mat Sci & Engn, Shenzhen 518055, Peoples R China
3.HKUST Shenzhen, Hong Kong Collaborat Innovat Res Inst, Shenzhen, Peoples R China
4.City Univ Hong Kong, Ctr Adv Struct Mat, Greater Bay Joint Div, Shenyang Natl Lab Mat Sci,Shenzhen Res Inst, Shenzhen 518057, Peoples R China
5.City Univ Hong Kong, Dept Mech Engn, Hong Kong, Peoples R China
6.City Univ Hong Kong, Shenzhen Futian Res Inst, Shenzhen 518045, Peoples R China
7.Shenzhen MSU BIT Univ, Shenzhen, Peoples R China

Wei, Pengbo,Hua, Peng,Xia, Minglu,et al. Bending fatigue life enhancement of NiTi alloy by pre-strain warm surface mechanical attrition treatment[J]. ACTA MATERIALIA,2022,240.

Wei, Pengbo.,Hua, Peng.,Xia, Minglu.,Yan, Kai.,Lin, Hongyang.,...&Sun, Qingping.(2022).Bending fatigue life enhancement of NiTi alloy by pre-strain warm surface mechanical attrition treatment.ACTA MATERIALIA,240.

Wei, Pengbo,et al."Bending fatigue life enhancement of NiTi alloy by pre-strain warm surface mechanical attrition treatment".ACTA MATERIALIA 240(2022).