Shot peening of austempered ductile iron gears

Abstract

This study investigates the suitability of shot peening as a surface treatment for austempered ductile iron (ADI) gears to lengthen their service life. Several studies have shown that shot peening prolongs the bending fatigue life of components. However, from the few works conducted on the tribological behaviour of ADI, it is not clear whether an improvement exists by shot peening. Hence, this work was conducted to study the contact fatigue resistance of shot peened ADI gears. Tests on as-ADI and shot peened ADI gears, as well as carburised steel gears were carried out. The results showed that the carburised steel gears exhibited superior performance and withstood the longest number of cycles before failure. The shot peened gears survived the lowest number of cycles. The poor performance after shot peening was attributed to an increase in the surface roughness induced by the peening process. In fact, the negative impact resulting from the roughened surface is greater than the benefits prompted by the induced compressive residual stresses, higher surface hardness and stress-induced austenite to martensite transformation.

Editorial: special issue on shot peening

“…The improvements resulting from the SP process on a variety of base materials, ranging from solid metals to alloys are discussed. These materials include austenitic stainless steel [4], AISI 1018 [1] and 4340 steel [5], S355 J2 structural steel [3], X65 steel [2], precipitation hardened ultrafine-grained copper alloy [6], austempered ductile iron [7] and Vitreloy 105 bulk metallic glass [8]. Yin et al [1] perform mathematical modelling and simulations of the kinetics of the process to predict the resulting surface topography of peened samples.…”

“…In some specific cases, the dimpled surface is sometimes considered to be favourable in lubricated contact, in which the resulting dimples act as lubricant reservoirs that maintain a full film thickness between mating surfaces [12,13]. Controversially, Zammit et al [7] reports a lower contact fatigue resistance of austempered ductile iron gears following SP. This was attributed to the mechanical interlocking of the asperities of the mating surfaces which accelerate pit formation during cycling.…”

“…Controversially, Zammit et al. [7] reports a lower contact fatigue resistance of austempered ductile iron gears following SP. This was attributed to the mechanical interlocking of the asperities of the mating surfaces which accelerate pit formation during cycling.…”

Gear fatigue of austempered ductile iron (ADI): an overview of numerical studies at UTFPR

“…ADI as gear material has been the subject of several studies [4][5][6][7][8][9], aiming to reduce manufacturing and machining costs and noise in service, in addition to improved gearing efficiency. ADI has been see as a possible substitute for steel alloy at different loading levels, as it combines adequate mechanical strength and high ductility, highlighting resistance to fatigue and wear [10].…”

Effect of the shot peening on the deformation of Al alloy component

“…The shot peening (SP) is widely applied to improve the mechanical properties of metals such as dislocation density, compressive residual stress (CRS), roughness and hardness, which serve to enhance the anti-fatigue ability and prolong the service life of SP parts [1][2][3][4][5]. In fact, this process has been popularly used in, for example, the aerospace and automobile industries due to cost effectiveness and high efficiency.…”