Abrasive wear behavior of different case depth gas carburized AISI 8620 gear steel

In this study, abrasive wear behaviors of gas carburized AISI 8620 steels with different case depths were examined. AISI 8620 steels yield excellent carburizing results and are used in manufacturing of gears. Two carburized and quenched specimens with different case depths were produced. Specimens were prepared at HEMA Gear Factory. Wear tests were carried out using pin-on disc test machine. Specimens were abraded under 10, 25 and 40 N loads by using 80 grid Al₂O₃ and SiC abrasive papers. Mass losses were measured using an electronic balance with accuracy of 10⁻⁴ g. Results of this study reveal that data on laboratory samples can be used to interpret the abrasive wear performance of AISI 8620 gas carburized steel gears. It has been observed that gas carburizing time affects the case depth, and in turn, specimen with higher case depth has shown better wear resistance. In addition to this, as the case depth has increased, the hardness of the material has increased as well.     

Abrasive wear behavior of boronized AISI 8620 steel

In this study, AISI 8620 steel was boronized using the solid state boronizing technique. Processes were carried out at the temperatures of 850, 900 and 950 °C for 2, 4 and 6 h of treatment. Abrasive wear behavior of the samples boronized at different temperatures and treatment durations have been examined. Using boronized and unboronized samples, abrasive tests were conducted using pin on disc test apparatus. 80 and 120 mesh aluminum oxide (Al₂O₃) abrasive papers were used in the abrasion experiments and the samples were subjected to abrasion under 10, 20 and 30 N loads. Boronized steels exhibited an improvement in abrasive wear resistance reaching up to 500%. Microstructures and wear surfaces of the samples were inspected using SEM microscopy. SEM examinations revealed that the thickness of the boride layer on the steel surfaces changes with changing process durations and temperatures. The presence of boride formed in the borided layer at the surface of the steels were determined by XRD analysis and microhardness values of the iron borides (FeB, Fe₂B) formed on the steel surface were found to be over 1600 HV.     

Effects of hardness on the solid particle erosion mechanisms in AISI 1060 steel

The mechanisms of mass loss were studied using impacts of single particles (WC spheres $\text{3}\text{16}$ in in diameter) for a 0.6% C steel (AISI 1060 steel) heat treated to give hardnesses of 12, 45 or 60 HRC. Both oblique and near-normal angles of impact were used. A new foil laminate was developed to measure rebound velocity and angle. Velocities of 100–200 m s^?1 were studied. A measurable mass loss was found only at 200 m s^?1. At a hardness of 12 HRC the mode of metal loss involved the loss of shear lips. At 60 HRC the dominant loss mode involves the intersection of adiabatic shear bands (ASBs) and shows a maximum mass loss at near-normal impact. The material with a hardness of 45 HRC shows both modes of mass loss and a maximum mass loss rate at oblique (30°) impact. ASBs on the surface and welding of target material to the impacting ball indicate a high temperature at the surface. However, the material welded to the particle is not a significant fraction of the material lost.     

Investigation into erosion rate of AISI 4340 steel during wire electrical discharge turning process

Wire electrical discharge turning (WEDT) process was developed to generate cylindrical form on any electrically conductive material applied in aerospace and automotive industry. The mechanism of metal removal in WEDT process is by means of successive spark discharge. Each spark results in the formation of crater. In the present work, a new model is proposed to predict the erosion rate of each spark for a given discharge energy. A new method is proposed to measure the crater depth from 2D roughness profile of the machined component. The proposed model is validated by conducting experiments on AISI 4340 steel and the results obtained are presented in the paper. It is observed that the results are in close proximity with the experimental values at low discharge energy. The stochastic erosion mechanism of WEDT process is analyzed using scanning electron microscope images of spark eroded wire. Using the proposed model the erosion rate can be controlled and better surface characteristic of machined surface can be achieved.     

Influence of the countermaterial on the dry sliding friction and wear behaviour of low temperature carburized AISI316L steel

Low temperature carburising (LTC) allows a significant hardness increase, with a consequent increase in wear resistance, without deteriorating corrosion behaviour. However, wear resistance strongly depends on contact conditions, therefore this work focuses on the dry sliding behaviour of LTC-treated AISI316L austenitic stainless steel against several countermaterials (AISI316L, LTC-treated AISI316L, hard chromium or plasma-sprayed Al₂O₃–TiO₂). LTC produced a hardened surface layer (C-supersaturated expanded austenite), which improved corrosion resistance in NaCl 3.5% and increased wear resistance, to an extent which depends on both normal load and countermaterial. The best results were obtained when at least one of the contacting bodies was LTC-treated, because this condition led to mild tribo-oxidative wear. However, LTC did not improve the behaviour in terms of friction.     

Coal slurry erosion of reaction-bonded SiC

The main problems associated with surfaces produced by electrodischarge machining, electrochemical machining and ultrasonic machining are outlined. Recommendations in the form of empirical approaches, special tool design or improved flow systems to aid the production engineer in the solution of such problems are given.     

Erosion of AISI 4140 steel

The erosion behavior of AISI 4140 steel under various heat treatment conditions was investigated. A variety of microstructures, such as the primary and tempered martensites, varying proportions of martensite and bainite, cementite spheroids embedded in a ferrite matrix and ferrite and pearlite were obtained. The erosion tests were performed in a sand-blast-type test rig. Except in the region where temper embrittlement occurred, the erosion decreased with increasing tempering temperatures. Erosion decreased with the increasing percentage of bainite in the austempered condition and also with increasing tempering time during spheroidization. From the point of view of the mechanical properties, erosion decreased with increasing ductility and decreasing hardness or ultimate strength. The abraded surfaces were also studied using scanning electron microscopy.     

Some Coriolis slurry erosion test developments

The Coriolis test has developed into a useful way of evaluating the slurry erosion behaviour of materials. Wear mapping has revealed some sensitivity to test conditions so both the tester and test procedures continue to evolve. Experiments with very dilute model slurries comprising a ‘pinch’ of glass beads, or a single glass bead, gave information on bead contact depth and normal component of impingement velocities which confirmed previous theoretical predictions that erodent particles interact with the specimen in a series of low angle impacts. The superior discriminating ability of the Coriolis slurry erosion test is due to the lower interaction intensity of erodent particles with target surfaces compared to that in slurry jet testing.     

Design of a slurry erosion test rig

The design of a jet impingement slurry erosion test rig, built for laboratory use, is presented. This apparatus gives good control over many of the important test parameters, such as impact velocity, solid particle concentration and impact angle. An ejector nozzle is employed to entrain sand particles from a sand bed into a stream of water to form a slurry; after impingement, the abrasive particles and the water phase are separated and recycled. This makes the rig simple, economical and easy to operate and its pump and pipeline remain free from erosive wear. Experimental results are presented to illustrate the operation and performance of the rig.     

Influence of temperature on the fretting response between AISI 301 stainless steel and AISI 52100 steel

Fretting of AISI 301 stainless steel sheet in contact with AISI 52100 steel from 20 °C to 550 °C in air and argon has been studied. Transitions in the mechanical properties of 301SS and oxidative behavior of this pair have been identified as a function of temperature. Strength and ductility of 301SS is reduced from 20 °C to 250 °C, increasing susceptibility to fretting damage. Steady state friction decreases as temperature increases, reducing cyclic stresses. Wear resistance increases in this temperature range, increasing fatigue damage due to the increase in fatigue life associated with increased wear. This study aims to identify the causes of the transitions in behavior and determine the net outcome of the competing effects with regard to fatigue damage.     

Study of solid particle erosion on AISI D2 using angular silicon carbide and steel round grit particles

Abstract

In this study, the performance of AISI D2 steel subjected to solid particle erosion tests was analysed. This material has applications for tools and dies for blanking, wood milling cutters, cold-extruding and other operations requiring high compressive strength and excellent wear resistance. The erosion tests performed by using a rig developed according to some parameters of the ASTM G76-95 standard. Two abrasive were used, angular silicon carbide (SiC) and steel round grit, both, with a particle size of 400–420 μm. This allowed comparing the erosion severity of each abrasive particle. The tests were conducted using four different incident angles 30, 45, 60 and 90° with a particle velocity of 24±2 m s^?1 and a flow rate of 21±2·5 g min^?1 for silicon carbide and 48·5±3·5 g min^?1 for the steel round grit. The exposure testing time was 10 min. Subsequently, the surface damage was analysed with a scanning electron microscope (SEM) to identify the wear mechanisms. Additionally, atomic force microscopy (AFM) was conducted in order to obtain roughness of the surface damage at 60°. The results indicated that higher amount of mass loss was obtained by angular silicon carbide particles.     

Quality control of carburized parts made from 15XM steel

A procedure for multiparameteric testing of the depth and hardness of a carburized layer, as well as the hardness of the core of a link bushing made from 15XM steel without the direct access to the cores material, is developed. The testing is based on the relative value of the coercive force that is measured using different schemes of magnetization of a specimen.Translated from Defektoskopiya, Vol. 40, No. 12, 2004, pp. 49–53.Original Russian Text Copyright © 2004 by Kostin, Stashkov, Nichipuruk, Sapozhnikova.This revised version was published online in April 2005 with a corrected cover date.     

基于累积损伤的渗碳齿轮钢疲劳寿命预测模型构建

采用轴向高频疲劳试验机进行超高周疲劳实验,研究了不同应力比(R=0和R=0.3)下渗碳齿轮钢疲劳特性。结果表明：在应力比为0和0.3时,渗碳齿轮钢的失效形式分为表面失效和内部失效。内部失效过程分为疲劳裂纹萌生阶段(夹杂-细颗粒区(fine granular area, FGA))、稳定扩展阶段(FGA-鱼眼)和瞬间断裂(鱼眼之外)。基于累积损伤法,建立了内部裂纹萌生和扩展阶段的疲劳寿命预测模型;最终建立了渗碳齿轮钢多应力比下的全寿命预测模型,预测精度较高。     

Laser welding of cast iron and carburized steel for differential gear

This study concerned laser welding replacing the traditional bolted connection of the ring gear and differential case in the power train of the automobile. Laser welding is necessary to reduce weight and manufacturing cost, since the bolted connection method requires additional parts and space. In the differential gear, however, it is difficult to control the welding processes because cast iron and carburized steel contain high carbon content. To solve these welding problems, laser welding using Ni-base filler metal was used in this work. The results of welding with Ni-base filler metal satisfied the torsional stiffness and durability, but compared to the bolted connection method, noise and hardness problems occurred. Therefore, to solve these problems, penetration depth was decrease from 5mm to 4mm and the carburized layer of the ring gear was cut with 1mm. As well, numerical method was used to evaluate welding deformation, torsional stiffness and fatigue.     

Magnetic abrasive finishing of hardened AISI 52100 steel

Surface finish has a vital influence on functional properties such as wear resistance and power loss due to friction on most of the engineering components. Magnetic abrasive finishing (MAF) is one of the advanced finishing process in which a surface is finished by removing the material in the form of microchips by abrasive particles in the presence of magnetic field in the finishing zone. In this study an electromagnet with four poles has been used which was found to give better performance in terms of achieving surface quality in lesser processing time. Voltage, mesh number, revolutions per minute (rpm) of electromagnet, and percentage weight of abrasives have been identified as important process parameters affecting surface roughness. The experiments were planned using response surface methodology and percentage change in surface roughness (??Ra) was considered as response. Analysis of experimental data showed that percentage change in surface roughness (??Ra) was highly influenced by mesh number followed by percentage weight of abrasives, rpm of electromagnet, and voltage. In this study, the least surface roughness value obtained was as low as 51?nm in 120?s processing time on a hardened AISI 52100 steel workpiece of 61 HRC hardness. In order to study the surface texture produced and to identify finishing mechanism, scanning electron microscopy and atomic force microscopy were also conducted. Shearing and brittle fracture of small portion of peaks of grounded workpiece have been found to be finishing mechanisms during MAF of AISI 52100 steel.     

Sand–water slurry erosion of API 5L X65 pipe steel as quenched from intercritical temperature

The objective of this study was to analyse the erosion of API 5L X65 pipe steel whose microstructure consisted of ferrite and martensite obtained by quenching from intercritical temperature (770°C). Jet impingement tests with sand–water slurry were used. The changes in mechanical properties, caused by heat treatment carried out, did not induce changes in either the mechanism or erosion resistance. The erosion rate increased with angle of attack until 30° and later decreased until 90°. The microtexture of the eroded surfaces, at angles of attack of 30° and 90°, were similar for both conditions and were composed of craters and platelets at several stages of evolution. The erosion mechanism was by extrusion with the forming and forging of platelets.     

Precision radial turning of AISI D2 steel

This paper compares finite element model (FEM) simulations with experimental and analytical findings concerning precision radial turning of AISI D2 steel. FEM machining simulation employs a Lagrangian finite element-based machining model applied to predict cutting and thrust forces, cutting temperature and plastic strain distribution. The results show that the difference between the experimental and simulated cutting force is near 20%, irrespectively of the friction coefficient used in the simulation work (approximately 19.8% for a friction of 0.25% and 18.4% for the Coulomb approach). Concerning the thrust force, differences of about 22.4% when using a friction coefficient of μ?=?0.25 and about 56.9% when using the Coulomb friction coefficient (μ?=?0.378) were found. The maximum cutting temperature obtained using the analytical model is 494.07°C and the difference between experimentation and simulation methods is 15.2% when using a friction coefficient of 0.25 and when using the Coulomb friction only 3.1%. Regarding the plastic strain, the differences between analytical calculations and FEM simulations (for the presented friction values) suggest that the finite element method is capable of predictions with reasonable precision.     

Wear of AISI 4340 steel under boundary lubrication

Wear tests were conducted using AISI 4340 steel sliding on AISI 01 tool steel under boundary lubrication conditions. The AISI 4340 steel was heat treated to obtain different microstructures and hardness levels. The results indicated that the wear behavior depends on the heat treatment procedure. It was found that hardness alone cannot be used as a measure of wear and that the microstructure and other mechanical properties should also be used. Chemical reaction products containing phosphorus, sulfur and zinc were found on the wear surfaces lubricated with a fully formulated light oil containing zinc dithiophosphates. The chemically reacted film was nonuniform and consisted of patches 1–1500 μm in size. The larger patches were formed on the surface of steel with a pearlite-ferrite microstructure and resulted in a high wear rate. In contrast, the small patches and the thin blue and brown films were formed on the wear surface of tempered martensite steel and produced low wear rates.     

Finite element modeling of burnishing of AISI 1042 steel

The aim of this study is to analyze the evolution of surface roughness finished by burnishing. Burnishing is done on a surface that was initially turned or turned and then ground. In a previous work, we have defined an analytical model to determine the R_t factor of burnished surfaces in relation to the feed f, the material displacement δ and the roughness R_ti of the initial surface. δ has been calculated using the Hertz contact theory which supposes that the behavior of the workpiece material is elastic. Hence, in this paper, we have defined a finite element model in which the elasto-plastic behavior of the piece is taken into account to determine the material displacement δ. This model has also permitted the calculation of the residual stresses related to the macroscopic contact geometry. Good correlations have been found between experimental and finite element results when burnishing an AISI 1042 steel.     

Electrochemical investigation of erosion-corrosion using a slurry pot erosion tester

The aim of this paper is to use a modified slurry pot erosion tester to perform in-situ electrochemical measurements during solid particle impingement to investigate the effects of velocity, sand size and sand concentration on a passive metal (UNS S31603). Samples are subjected to a set of erosion-corrosion experiments. The electrochemical response of UNS S31603 to the test parameters is plotted and compared to develop an understanding of the erosion-corrosion process. The current trend with variation of test parameters has been explained by an erosion enhanced corrosion synergistic effect. The current transients associated with depassivation and repassivation during solid particle impingement are observed through electrochemical noise measurements. It was observed that the increase in velocity and sand concentration increased the current levels during erosion-corrosion. However, the increase in sand size had a more complex response. Single particle impact experiments conducted revealed that the peak corrosion current and the repassivation time increased with increase in velocity. A linear trend was seen between the peak current and the kinetic energy. A second-order exponential decay was fitted to the repassivation kinetics of the single particle impact. SEM has been used to develop a mechanistic understanding of erosion-corrosion. The surface scars reveal that the depth of the craters and the length of the lips increase with increase in velocity. Micro-cracks also appear on these lips, believed to be due to corrosive action attacking the roots of these lips.