This work deals with the influence of surface mechanical attrition treatment (SMAT) duration on fatigue lives of Ti-6Al-4V. The SMAT process was carried out in vacuum with SAE 52100 steel balls of 5 mm diameter for 30 and 60 min at a vibrating frequency of 50 Hz. SMAT treated surface was characterized by electron microscopy. Surface roughness, nano-indentation hardness, residual stress, and tensile properties of the material in both SMAT treated and untreated conditions were determined. SMAT enabled surface nanocrystallization, increased surface roughness, surface hardness, compressive residual stress and tensile strength but reduced ductility. Samples treated for 30 min exhibited superior fatigue lives owing to positive influence of nanostructured surface layer, compressive residual stress and work hardened layer. However, fatigue lives of the samples treated for 60 min were inferior to those of untreated samples due to presence of microdamages or cracks induced by the impacting balls during the treatment. © 2013 Indian Institute of Metals.

S. Ganesh Sundara Raman

Department of Metallurgical and Materials Engineering

Satendra Anand Kumar

T. S. N. Sankara Narayanan

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Transactions of the Indian Institute of Metals

Surface mechanical attrition treatment (SMAT) was carried out on Ti-6Al-4V. Fretting wear tests were conducted using two counterbody materials (alumina and steel). SMAT resulted in surface nanocrystallization. Due to high hardness, low tangential force coefcient (TFC) and more TiO 2 layer, fretting wear resistance of SMAT treated samples was higher than that of the untreated samples. TFC values obtained with alumina counterbody were higher than those obtained with steel counterbody. The fretting wear resistance of untreated and treated samples fretted against alumina was lower than that of the samples fretted against steel due to tribochemical reactions at the contact zone. © 2012 Elsevier Ltd.

Tribology International

Influence of counterbody material on fretting wear behaviour of surface mechanical attrition treated Ti-6Al-4V

Ti-6Al-4V alloy was subjected to surface mechanical attrition treatment (SMAT) by using SAE 52100 steel balls of 5 mm diameter for two treatment durations (30 and 60 min). SMAT resulted in the formation of nanostructured material on the surface and near surface regions, increased hardness, increased surface roughness and compressive residual stress on the surface. Treated samples exhibited lower tangential force coefficient (TFC) compared to untreated samples. Samples treated for 60 min exhibited higher grain refinement, higher hardness, lower surface roughness and higher TFC compared to the samples treated for 30 min. Fretting wear resistance of the samples treated for 30 min was higher than that of untreated samples and the samples treated for 60 min. Due to very high hardness and presumably reduced ductility, the fretting wear resistance of the samples treated for 60 min was lower than that of the untreated samples and samples treated for 30 min. © (2012) Trans Tech Publications.

Advanced Materials Research

Influence of surface mechanical attrition treatment on fretting wear behaviour of Ti-6Al-4V

The effect of surface mechanical attrition treatment (SMAT) and its duration on fatigue lives of alloy 718 has been studied. The SMAT process was carried out in vacuum (-0.1 MPa) with SAE 52100 steel balls of 5 mm diameter for 30 and 60 min at a vibrating frequency of 50 Hz. SMAT resulted in surface nanocrystallization, higher surface roughness, higher surface hardness, higher compressive residual stress, higher tensile strength, reduced ductility and superior fatigue lives. The enhancement in the fatigue lives of treated samples can be attributed to the positive influence of nanostructured surface layer, compressive residual stress and work hardened layer, which surpassed the negative effect of increased surface roughness. There was no significant difference between the fatigue lives of samples treated for 30 and 60 min. © Indian Institute of Metals 2012.

Effect of surface mechanical attrition treatment on fatigue lives of alloy 718

Alloy 718 was subjected to surface mechanical attrition treatment (SMAT) using SAE 52100 steel balls of a 5. mm diameter for four different treatment durations (15, 30, 45 and 60. min). Fretting wear tests were conducted at different normal loads on untreated and treated samples for 25,000. cycles using alumina as a counterbody material. Microstructural features of the surface layer of samples treated by SMAT were characterized by cross-sectional optical microscopy and transmission electron microscopy. Hardness, surface roughness and residual stress were determined using a nano-indenter, surface roughness tester and X-ray residual stress analyzer respectively. SMAT resulted in the formation of nanocrystallites on the surface and near surface regions, increased hardness, increased surface roughness and compressive residual stress at the surface. Treated samples exhibited lower tangential force coefficient (TFC) compared to untreated samples. Samples treated for 60. min exhibited higher grain refinement, higher hardness, lower surface roughness and higher TFC compared to the samples treated for 30. min. The wear volume and wear rate of samples treated for 30. min were lower compared to those of the untreated samples, which may be attributed to an optimum combination of hardness and toughness and a low work hardening rate of the nanocrystalline structure at the surface of the treated samples. In contrast, the wear volume and wear rate of the samples treated for 60. min were higher than those of untreated samples, presumably due to the higher hardness and reduced toughness of the samples treated for 60. min. © 2012 Elsevier B.V.

Surface and Coatings Technology

Fretting wear behaviour of surface mechanical attrition treated alloy 718

Materials & Design

Surface state of Inconel 718 ultrasonic shot peened: Effect of processing time, material and quantity of shot balls and distance from radiating surface to sample

Journal	Transactions of the Indian Institute of Metals
ISSN	09722815
Open Access	No