Microstructural developments during abrasion of M50 bearing steel

doi:10.1016/j.wear.2014.03.010

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Volume 315, Issues 1–2, 15 July 2014, Pages 31-37

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Highlights

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Development of ferritic structure during abrasion.
•
Development of martensite structure during abrasion.
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Martensite lath sheared feature during abrasion.
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Higher abrasion resistance of martensite than ferrite.

Abstract

Current study has been carried out to compare the development of microstructure in deformed zone of M50 bearing steel during abrasion. Three-body abrasive wear was carried out using abrasive test apparatus as per ASTM G 65-85 with applied load of 13 kg. Silica sand of dimension 200±50 μm was used as abrasives. The effect of deformed features in abrasion resistance has also been delineated. Crystallographic lath pocket oriented sheared features were observed after abrasion of martensite. Very less fractions of crystallographic sheared features were observed after abrasion of ferrite. The abrasion did not produce dislocation cell structure in ferrite. Ferrite associated just more dynamic recovery while martensite was concomitant to greater dynamic recrystallization. Major toughness enhancement by abundant sheared features and dynamic recrystallization in martensite resulted in higher abrasion resistance of martensite than ferrite.

Introduction

Progress in science and technology has increased the demand for bearing materials with enhanced properties used in demanding environment. It has resulted in development of several varieties of bearing steels [1], [2], [3], [4]. Aerospace engines require the bearing steel to be used at elevated temperature in the range of 300–350 °C. The secondary hardened M50 steel is one of the best to retain its high strength, hardness, toughness and contact fatigue resistance for elevated temperature use [5]. Though, rolling contact fatigue property is one of the crucial parameters defining the quality of bearing material, the bearings also go through other tribological phenomenon such as abrasion. Failure analysis of engineering components indeed reveals that typically components fail by abrasion due to depletion of lubricants, generation of debris and ingestion of dirt [6], [7], [8]. Therefore, the abrasion resistance of M50 steel has been the topic of the current study.

The progressive trend of abrasion resistant steel development is oriented to proper microstructural design. Plastic deformation during wear and abrasion produces dislocations, dislocations cells, grain refinement and deformation bands [9], [10], [11], [12], [13], [14], [15], [16]. The formation of deformed structure is governed by composition and crystal structure [17], [18], [19]. The role played by Stacking Fault Energy (SFE) in this context is crucial [20].

The hard martensite is believed to be associated with the highest abrasion resistance [21]. Report has showed that comparatively softer multiphase steels with high ductility and toughness can have higher sliding wear resistance than harder steels [22]. The earlier result has also been strengthened by other data [23]. According to Rendón et al. the additional high toughness as well as with hardness could be the best way to enhance impact and sliding abrasion resistance [24]. The hardened surface of steels by nitro-carburizing induces compressive residual stress and it provides additional abrasion resistance [25]. Reports suggest that wear rate varies with the thermal stability of the phases, resistance to plastic deformation and resistance to micro-crack initiation and propagation. The order of increasing sliding wear resistance for steel has been found to be (martensite+carbide+retained austenite)–(ferrite+globular carbide)–(martensite)–(bainite)–(lamellar pearlite) [22], [26], [27].

The developed microstructural features of materials after abrasion have hardly been studied. Ives [10] and Brygmann et al. [11] have reported formation of fine grain crystalline structure and dislocation cell structure beneath the abraded surface of Cu and Cu thin film respectively. Lawless [13] also has noted dislocation cell structure in the region below the worn surface of Cu film. Dislocation concept in friction and wear has been discussed extensively with the help of TEM images by Kuhlmann-Wilsdorf [14]. Ultra-fine grained aluminum layers, which extend up to 10 μm, have been formed beneath the tribolayers under sliding wear conditions as reported by Li et al. [16]. These fine-grained structures were presumably formed due to severe plastic deformation because the microstructural investigations did not show signs of recrystallization under the wear conditions.

With the above background and also because of the fact that deformation behavior of the material during abrasion is associated with some structural features, the current study has been carried out. It has explored the development of microstructure in the deformed zone and emphasized the effect of structural features in the abrasion resistance of M50 bearing steel.

Section snippets

Material and methods

Bearing steel with composition as given in Table 1 was used as investigated material. The steel contains 3.72 wt% Cr, 4 wt% Mo, 1 wt% V and about 0.72 wt% C. The composition in weight percentage (%) was analyzed using inductively coupled plasma optical emission spectrophotometer and the interstitial elements were analyzed by LECO instrument.

During hardening treatment material was preheated to 850 °C soaked for 30 min. The temperature was then raised from 850 °C to 1110 °C, soaked for five minutes

Results

The true stress (σ)–true strain (ε) plots of this alloy before and after hardening are presented in Fig. 2. From these plots various parameters like yield strength (σ_YS), ultimate tensile strength (σ_UTS), uniform strain (ε_u), and fracture strain (ε_f) have been determined. The tensile properties of these materials are listed in Table 2. Ferrite reveals higher ductility and toughness than martensite.

The SEM micrographs in Fig. 3(i) and (ii) reveal the ferritic structure before hardening and

Discussion

Deformation behavior of metallic materials during abrasion has several similar and dissimilar features. During abrasion the stress state under which the plastic deformation occurs is multi-directional and compressive. As the thickness of the sample or the component is considerably larger than the plastic zone size, the plastic zone surrounding the indenting particle is completely confined. These features develop constrained plastic flow in the presence of hydrostatic compressive stresses. The

Conclusions

(i)
Lath pocket oriented sheared features were found after abrasion of martensitic structure but very less fractions of crystallographic shear bands were observed after abrasion of ferrite.
(ii)
Taylor factor based on high work hardening rate and accumulation of high localized strain during abrasion developed shear band.
(iii)
Ferrite associated just more recovery while martensite was concomitant to greater dynamic recrystallization.
(iv)
Major toughening by abundant sheared features and dynamic recrystallization of

Acknowledgments

Authors gratefully acknowledge the grant for the project Speciality steel in defence application DMR-292 by DRDO and would like to sincerely thank director DMRL, Dr. A.A. Gokhale for his continuous encouragement.

References (40)

H.K.D.H. Bhadeshia
Steels for bearings
Prog. Mater. Sci.
(2012)
D. Scott
Debris examination – a prognostic approach to failure prevention
Wear
(1975)
R. Büscher et al.
The effects of subsurface deformation on the sliding wear behavior of a microtextured high-nitrogen steel surface
Wear
(2004)
N.P. Suh
An overview of the delamination theory of wear
Wear
(1977)
I.I. Garbar
Abrasion resistance as a function of substructural changes in steel
Wear
(2005)
J. Li et al.
FIB and TEM characterization of subsurfaces of an Al–Si alloy (A390) subjected to sliding wear
Mater. Sci. Eng. A
(2006)
E. Nes et al.
On the mechanisms of dynamic recovery
Scr. Mater.
(2002)
S. Sato et al.
Microstructural characterization of high-manganese austenitic steels with different stacking fault energies
Mater. Charact.
(2011)
Y. Wang et al.
Tribo-metallographic behavior of high carbon steels in dry sliding: II. Microstructure and wear
Wear
(1999)
V. Ratia et al.
Surface deformation of steels in impact-abrasion: the effect of sample angle and test duration
Wear
(2013)

J. Rendón et al.

Abrasive wear resistance of some commercial abrasion resistant steels evaluated by laboratory test methods

Wear

(2009)

K.S. Al-Rubaie et al.

Two-body abrasion of nitrocarburised steels for hydraulic cylinders

Wear

(2000)

Y. Wang et al.

Wear behavior of steel 1080 with different microstructures during dry sliding

Wear

(1996)

N. Jin et al.

Effect of microstructure on rolling/sliding wear of low carbon bainitic steels

Wear

(1997)

N. Jia et al.

Orientation dependence of shear banding in face-centered-cubic single crystals

Acta Mater.

(2012)

S. Kibey et al.

Effect of nitrogen on generalized stacking fault energy and stacking fault widths in high nitrogen steels

Acta Mater.

(2006)

J. Liu et al.

Influence of Ni and N on generalized stacking-fault energies in Fe–Cr–Ni alloy: a first principle study

Phys. B: Condens. Matter

(2012)

A. Abbasi et al.

First-principles investigation of the effect of carbon on the stacking fault energy of Fe–C alloys

Acta Mater.

(2011)

H. Paul et al.

Shear band microtexture formation in twinned face centred cubic single crystals

Mater. Sci. Eng. A

(2003)

T. Leffers et al.

Intra- and intergranular heterogeneities in the plastic deformation of brass during rolling

Acta Metall. Mater.

(1990)

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Microstructural developments during abrasion of M50 bearing steel

Highlights

Abstract

Introduction

Section snippets

Material and methods

Results

Discussion

Conclusions

Acknowledgments

Prog. Mater. Sci.

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Mater. Sci. Eng. A

Scr. Mater.

Mater. Charact.

Wear

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Acta Mater.

Acta Mater.

Phys. B: Condens. Matter

Acta Mater.

Mater. Sci. Eng. A

Acta Metall. Mater.