A. Alsaran

Effect of post-oxidizing on tribological and corrosion behaviour of plasma nitrided AISI 5140 steel

Abstract A post-oxidation treatment was performed for times of 15, 30 and 60 min at a substrate temperature of 500 °C to investigate the tribological and corrosion properties of plasma nitrided AISI 5140 steel. The structural, mechanical, tribological and corrosion properties were analyzed by using XRD, SEM, microhardness testing, surface profilometry, pin-on-disk tribotesting and electrochemical polarization. The experimental results showed that oxide layer consists of magnetite (Fe 3 O 4 ) and hematite (Fe 2 O 3 ) phases. With increasing oxidation time, the thickness of the compound layer decreased due to the sputtering as a result of prolonged oxidation. In addition, it was found that the oxidation treatment after plasma nitriding provided an important improvement in the friction coefficient against a WC-Co ball, the wear rate and the corrosion resistance.

Mechanical and structural properties of similar and dissimilar steel joints

The mechanical properties of specimens from similar and dissimilar weld joints were examined. A ferritic steel (St37-2) and an austenitic stainless steel (AISI 304) were joined by the gas tungsten arc weld (GTAW) process using an austenitic filler metal. Mechanical and metallographic properties of the specimens were obtained by means of microhardness testing, tensile testing, bending fatigue testing, and light optical and scanning electron microscopy. The highest microhardness values were recorded on the ferritic-austenitic dissimilar weld joint, whereas the highest tensile strength and bending fatigue life were obtained with the austenitic-austenitic joints. Ferritic and pearlitic structures were observed in the microstructure of the ferritic-ferritic joint. The microstructures of austenitic-austenitic and austenitic-ferritic joints showed small recrystallization grains in addition to the typical austenitic and ferritic structures. Scanning electron microscopy was used to observe the fracture surfaces of the specimens and the origins of the fatigue cracks.

Structural characterization of ion-nitrided AISI 5140 low-alloy steel

The ion nitriding behavior of AISI 5140 alloy steel was investigated under different process parameters including time (1, 4, 8, and 12 h), temperature (400, 450, 500, and 550 � C), and gas mixture ratio (0.05, 0.33, 1, and 3 N2/H2). The ion nitriding of steels has been assessed by evaluation of phase composition, hardness profile, compound layer thickness, and case depth by using a microhardness tester, X-ray diffraction (XRD), and scanning electron microscopy (SEM). It is observed that the compound layer thickness and the case depth increase with increasing treatment time and temperature. With increasing gas mixture ratio, the compound layer thickness increases, whereas the case depth decreases. The maximum surface hardness was observed at 450 � C temperature, for 0.33 N2/H2 gas mixture ratio, and for 4-h treatment time. D 2001 Elsevier Science Inc. All rights reserved.

The investigation of mechanical properties of ion-nitrided AISI 5140 low-alloy steel

Abstract The ion nitriding behavior of AISI 5140 low-alloy steel was investigated under different process parameters including time (1, 4, 8, and 12 h), temperature (400, 450, 500, and 550 °C), and gas mixture ratio (0.05, 0.33, and 3 N2/H2). The ion nitriding properties of AISI 5140 steel have been assessed by evaluating fatigue strength, hardness profile, compound layer thickness, and case depth by using a rotating bending fatigue machine, a microhardness tester, and scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS). It was found that ion nitriding improves the fatigue strength, which depends on increasing the case depth, but the compound layer does not have a dominant effect on the fatigue strength. After the fatigue tests, sections of ion-nitrided specimens were observed to have failed by the fish eye phenomenon with the fatigue cracks originating from nonmetallic inclusions.

Determination of the optimum conditions for ion nitriding of AISI 5140 steel

Abstract AISI 5140 low alloy steel was ion nitrided under different process parameters including time (1, 4, 8 and 12 h), temperature (400, 450, 500 and 550 °C) and gas mixture ratio (0.05, 0.33, 1 and 3 N 2 /H 2 ). By determining the fatigue strength, surface hardness, compound layer thickness and case depth, the optimum working conditions were determined by using a Taguchi design of experiment. After ion nitriding process, it is aimed to maximize fatigue strength, surface hardness and case depth as well as to minimize compound layer thickness. While the optimum conditions were determined, due to the goals (above aims) more than one being, the trade-off among goals was considered. First of all, each goal was optimised, separately. Then, all the goals were optimised together, considering the priority of the goals, and the optimum results were obtained at 0.05 N 2 /H 2 gas mixture ratio, at the temperature of 450 °C and for 12 h process time.

Deposition and Adhesion Characterization of Ti(BN:MoS2) Based Composite Thin Films Prepared by Closed-Field Unbalanced Magnetron Sputtering

Composite structured solid thin films were deposited on 52100 tool steel by co-sputtering from BN, TiB2, MoS2 and Ti targets using a closed-field unbalanced magnetron sputtering process (CFUBMS). The structural and mechanical properties of the composite structured coatings were investigated. The composition and morphology of the films were investigated using X-ray diffraction and scanning electron microscopy (SEM). The adhesion properties of the films were characterized by the use of a Revetest-scratch tester. The adhesion test results indicated that bias voltage was the most effective coating parameter related to the critical load.

Effect of Plasma Nitriding Parameters on the Wear Resistance of Alloy Inconel 718

The effect of the temperature and duration of plasma nitriding on the microstructure and friction and wear parameters of Inconel 718 nickel alloy is investigated. The process of plasma nitriding is conducted in a nitrogen-hydrogen gaseous mixture at a temperature of 400, 500 and 600°C for 1 and 4 h. The modulus of elasticity of the nitrided layer, the micro- and nanohardness, the surface roughness, the friction factor and the wear resistance of the alloy are determined prior to and after the nitriding. The optimum nitriding regime providing the best tribological characteristics is determined.

Performance of Plasma Sprayed Al2O3 Coating in Bio-Simulated Environment

Alumina coatings deposited on the surface of stainless steel 316L by the method of plasma spraying are studied. Tests for wear and corrosion are preformed in Ringer’s solution simulating a human body environment. The structure, microhardness, wear resistance and corrosion resistance of the steel are determined with and without a coating. Deposition of a coating onto the stainless steel is shown to be an effective means for protecting implants from corrosion and wear.

Effect of Boron Nitride Coating on Wear Behavior of Carbide Cutting Tools in Milling of Inconel 718

Boron nitride based tribological coatings promise hope in tribological applications thanks to their excellent lubrication and heat resistance properties. However, the applicability of these coatings on cutting tools in machining applications is not well known and it needs to be revealed. Therefore, in this study, a boron nitride (BN) coating was deposited on carbide milling tools. Inconel 718 was used as workpiece material in face milling tests to determine the wear behavior of the BN coated carbide tools. Surface roughness and tool wear was recorded in relation with cutting length. Wear mechanisms on the coated carbide tools were determined using scanning electron microscopy in combination with energy dispersive spectroscopy. Abrasive and adhesive wear was found as main failure mechanisms on the worn tools. Approximately two times longer tool life was obtained with the BN coated carbide tools.

The wear behaviour of duplex treated AISI 5140 steel

Purpose – This work aims to investigate the wear behavior of manganese phosphate coating on plasma nitrided AISI 5140 steel.Design/methodology/approach – Prior to manganese phosphate coating, plasma nitriding of substrates was performed at gas mixture of 50 percent H2 and 50 percent N2, for the different treatment parameters. The structural, mechanical and tribological properties of the substrates were determined using hardness test, optical microscope, scanning electron microscopy , X‐ray diffraction and pin‐on‐disk tribotester. The wear behavior of untreated, nitrided and duplex treated substrates was evaluated under dry sliding conditions.Findings – The results indicated that the duplex treatment improved the wear behavior. It was also observed that manganese phosphating of the nitrided substrates at low temperature (450°C‐2h‐N) resulted in a decrease of the wear rate and yielded a reduction in the friction coefficient by forming a transfer film at the counter face.Originality/value – This study can be...