Effect Of White Layer Research Articles

Effect of white layer on residual autofrettage stresses and strains in open – end cylinders

A semi-analytic solution for residual autofrettage stresses and strains in open-end cylinders is given. The primary objective of this research is to reveal the effect of white layer in the vicinity of the inner radius of the cylinder on the magnitude of residual stresses and strains at this radius. In contrast to many available semi-analytic solutions for residual autofrettage stresses and strains, the von Mises yield criterion and its associated flow rule are adopted. A remarkable property of the solution found is that the residual stresses and strains in the white layer can be determined without solving the strain equations in the plastic region. Therefore, the solution is rather simple. In particular, numerical techniques are only necessary to solve transcendental and ordinary differential equations.

An Experimental Study on the Effect of Machining-Induced White Layer on Frictional and Wear Performance at Dry and Lubricated Sliding Contact

The frictional and wear performance of a machined component depends strongly on the surface properties. A white layer on the machining surface is often produced at abusive machining conditions. However, the effect of white layer on frictional and wear performance has received little attention. Dry and lubricated sliding contact tests for white layer surfaces by turning and grinding were carried out at different load levels on a ball-on-disk tribometer with real-time monitoring of the wear process using an acoustic emission sensor. The experimental results show that the existence of a turned white layer slightly decreases the coefficient of friction (COF), while a ground white layer significantly increases COF at dry conditions. At lubricated conditions, the turned white layer only slightly increases COF while the ground white layer slightly reduces it. The trends of acoustic emission (AE) amplitude are consistent with those of COF at dry conditions for the turned or ground surfaces. At lubricated conditions, a turned white layer increases the AE amplitude with the increase of normal load when compared with a turned fresh surface. The ground white layer makes AE amplitude much smaller than that of the ground fresh surface at high normal load. The third body wear debris may act as solid lubricants leading to reduced friction. A turned white layer shows better wear resistance than the turned fresh surface. However, the ground white layer has poor wear resistance than the ground fresh one at large load.

Effect of surface integrity of hard turned AISI 52100 steel on fatigue performance

This paper addresses the relationship between surface integrity and fatigue life of hard turned AISI 52100 steel (60–62 HRC), with grinding as a benchmark. The impact of superfinishing on the fatigue performance of hard turned and ground surfaces is also discussed. Specifically, the surface integrity and fatigue life of the following five distinct surface conditions are examined: hard turned with continuous white layer, hard turned with no white layer, ground, and superfinished hard turned and ground specimens. Surface integrity of the specimens is characterized via surface topography measurement, metallography, residual stress measurements, transmission electron microscopy (TEM), and nano-indentation tests. High cycle tension–tension fatigue tests show that the presence of white layer does not adversely affect fatigue life and that, on average, the hard turned surface performs as well or better than the ground surface. The effect of superfinishing is to exaggerate these differences in performance. The results obtained from this study suggest that the effect of residual stress on fatigue life is more significant than the effect of white layer. For the hard turned surfaces, the fatigue life is found to be directly proportional to both the surface compressive residual stress and the maximum compressive residual stress. Possible explanations for the observed effects are discussed.

Effect of white layer on cracking resistance of steel in a sulfuric acid solution

It has been found [1-3] that the cracking res is tance of tubular specimens {wall thickness 1.75 mm) with a white layer in sulfuric acid solutions is appreciably lower than with solid specimens. To find the reasons for this phenomenon, additional tes t s have been made in 20% sulfuric acid Solution on solid and tubular specimens of 40Kh steel with various wall th icknesses (external diam. 20 mm; internal diam. 17, 15, 13, 11 mm; working length 70 mm). Heat t reatment : oil hardening f rom 850~ temper ing at 180~ (2 h). The white layer on the surface of the specimens was prepared according to the following schedule: cutting rate 71 m / m i n , feed 0.3 mm/revolu t ion , cutting depth 004 mm, cut rake 45 ~ radius at c res t of cut 1 mm. The surface finish was V5. The specimens were subjected to uniaxial extension on lever machines.