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.

S. Ganesh Sundara Raman

Department of Metallurgical and Materials Engineering

Rajappa Gnanamoorthy

Department of Mechanical Engineering

S. Anand Kumar

T.S.N. Sankara Narayanan

Compressive residual stress

FRETTING WEAR BEHAVIOUR

FRICTION AND WEAR

HIGH HARDNESS

NANOSTRUCTURED SURFACE

NEAR SURFACE REGIONS

SMAT

STEEL BALLS

SURFACE MECHANICAL ATTRITION TREATMENTS

TANGENTIAL FORCE COEFFICIENT

Ti-6Al-4V

Ti-6Al-4V alloy

treatment duration

FRETTING CORROSION

Grain refinement

Grain size and shape

Hardness

Nanostructured materials

Surface roughness

Titanium alloys

Wear resistance

Surfaces

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IIT Madras

Advanced Materials Research

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.

Transactions of the Indian Institute of Metals

Influence of surface mechanical attrition treatment duration on fatigue lives of Ti-6Al-4V

In the present work, multi layer perceptron feed forward artificial neural network (ANN) technique was employed to predict the fretting wear behavior of surface mechanical attrition treated and untreated Ti-6Al-4V fretted against alumina and steel counterbodies. A three-layer neural network with a gradient descent learning algorithm was used to train the network. Three input parameters normal load (L), surface hardness of the test material (H) and hardness of counterbody material (CB) were employed in construction of ANN. Tangential force coefficient (TFC), fretting wear volume and wear rate obtained from a series of fretting wear tests were used in the training and testing data sets of ANN. Ranking of the importance of input parameters on the output TFC was found to be in the order of L &gt; CB &gt; H. For wear volume and wear rate, it was found in the order of L &gt; H &gt; CB. The degrees of accuracy of predictions were 96.6%, 96.1% and 92.2% for TFC, wear volume and wear rate respectively. Owing to the good correlation between the predicted values and the experimental results, ANN can be used in the prediction of fretting wear behavior. © 2013 Elsevier Ltd.

Materials and Design

Prediction of fretting wear behavior of surface mechanical attrition treated Ti-6Al-4V using artificial neural network

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

Rolling element bearings experience fretting wear type of failures due to small relative oscillatory motion existing between races and rolling elements of the bearing. Small oscillatory motion between contacting surfaces that occur due to overall machine or system vibration and unexpected loads in service causes accumulation of wear debris in the contact zone and accelerate the wear process. A fretting wear test rig is designed and developed in the laboratory for understanding the fretting wear behavior of bearing materials. The test rig is designed for testing at slip amplitudes ranging from 20 to 200 μm and test frequencies ranging from 1 to 30 Hz. Preliminary studies for understanding the fretting wear characteristics were conducted on hardened and tempered bearing steel, En31 and widely employed hardened and tempered structural steel, En24 at various normal loads. Coefficient of friction during fretting tests was high during the initial stages of fretting tests and reached a steady state. The coefficient of friction depends on the normal load. Wear scar morphology reveals the nature of contact exhibited by the fretting contacts. © 2004 Elsevier Ltd. All rights reserved.

Development of a fretting wear test rig and preliminary studies for understanding the fretting wear properties of steels

Corrosion Science

Effect of surface nanocrystallization on the corrosion behaviour of AISI 409 stainless steel

Wear

Fretting wear behavior of nanocrystalline surface layer of copper under dry condition

Scripta Materialia

Grain size effect on wear resistance of a nanostructured AISI52100 steel

Acta Materialia

Plastic strain-induced grain refinement at the nanometer scale in copper

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

Journal	Advanced Materials Research
ISSN	10226680
Open Access	No