The use of laser radiation to increase the efficiency of nitriding processes

In this study, the technology of laser processing is tested. This combined process of laser chemical-thermal treatment allows by modifying the structures of the surface layers of metal alloys to significantly increase the thickness range of high-quality nitrided layers with a radical reduction in time and energy consumption of the process, significantly expand their applications to increase wear resistance, corrosion resistance and other performance characteristics.

The Study of the Formation Process of Microstructure and Properties during Laser Alloying of the Surface of the Structural Steels

Development and implementation of new methods of high-energy surface treatment of structural steels is one of the priorities of modern materials science One of the urgent problems of power engineering is the development of effective processing technologies that allow parts to provide the required properties of working surfaces. The use of laser technologies helps to increase wear resistance, corrosion resistance, reduce the duration of chemical and thermal treatment time and other technological characteristics that can improve the quality, durability and efficiency of parts, increase economic and environmental effects.

Development of a technology of gas-flame application of powders to increase wear resistance and adhesion strength

Every year, the world economy suffers enormous losses due to wear and corrosion of machine parts and equipment. With targeted preventive protection against wear and tear, these losses can be avoided. Along with the coating of new parts, this includes the restoration of worn parts. An effective method is the surfacing of materials with high performance properties. The quality of hardened parts depends on the properties of deposited material, so hardening material or alloy is selected taking into account the working environment of the part and the coating method. Today there are many self-fluxing surfacing powder alloys based on nickel, copper and others, obtained by different methods. The paper discusses the process of studying the gas-flame application of powders to increase wear resistance and adhesion strength. Experimental studies have been carried out to determine the optimal composition of the CrB2 master alloy introduced into the composition of the GP-Ir40 surfacing alloy. It has been found that to obtain the hardness of the deposited metal in the range of 450–600 HV, it is necessary to introduce CrB2 into the coating composition, within 10 % of the total mass. Thus, the strength of the alloy is increased by more than 54.41 HV. Tests for corrosion resistance in aggressive environments of hydrogen sulfide H2S, sulfuric acid H2SO4 were carried out. The wear resistance of ground pumps was evaluated, and the service life of wear-resistant ground pump parts made of the IChH28N2 alloy was determined. The new developed self-fluxing surfacing powder material based on iron with a hardening additive will be used to restore machine and equipment parts operating under conditions of abrasive wear, corrosion and elevated temperatures or corrosive environments

Wear evaluation and microstructure analysis of cryogenically treated AISI 440C Bearing steel

In this research work, two types of cryogenic treatment such as deep cryogenic treatment (-196oC) and shallow cryogenic treatment (-80oC) have been adopted for wear resistance to increase in AISI 440C bearing steel. This paper has been focused to increase Wear Resistance (WR) through deep micro structural analyses, and also attention has been made to correlate the microstructure with the wear character of Deep Cryogenic treated (DCT) specimens, Conventional Heat Treated (CHT) specimens and Shallow Cryogenic Treated (SCT) specimens. Micro structural examinations have been carried out in the specimens through Scanning Electron Microscopy (SEM), Energy Dispersive Analysis of X-ray (EDAX) and X-Ray Diffraction (XRD). Wear characteristics of AISI 440C bearing steel has been studied. The outcome of the research disclosed that the DCT specimens have higher wear resistance than SCT and CHT specimens. The effective wear mechanisms recognized were the constitution of white layers and delamination of white layers. The microstructures of the materials have been varied through heat treatment process. The modification of Secondary Carbides (SCs) precipitation characteristics and its reduction of retained austenite in the microstructure have been correlated with wear character and these are the liable mechanism to raise the wear resistance of bearing steels through DCT.

Adjusting Mechanical Properties of Forging Dies Produced by Ausforming

Due to high thermo-mechanical loads, tools used in hot forming operations need a high resistance to different damage phenomena, such as deformation, cracking and abrasion. They are exposed to cyclic thermo-mechanical stress conditions, which leads to tool failure and subsequent tool replacement during cost-intensive production interruptions. To increase wear resistance, forging tools can be produced in the metastable austenite area. Forming of steel below the recrystallisation temperature, also known as “ausforming”, offers the possibility to increase strength without affecting ductile properties. This is due to grain refinement during forming. In this study, the thermo-mechanical treatment ausforming will be used to form the final contour of forging dies. For this purpose, an analogy study was performed where a cup-preform is ausformed, which represents the inner contour of a highly mechanically loaded forging die. It is investigated to what extent a fine-grained microstructure generated in the last forming stage can be achieved and how it influences the tool’s performance. The hot-working tool steel X37CrMoV5-1 (AISI H11) was used as workpiece material. To achieve optimal properties, process routes with tempering temperatures from 300 °C to 500 °C and global true plastic strains of φ = 0.25 and φ = 0.45 were examined. The results were evaluated by pulsation tests, metallographic analysis and hardness measurements of the formed parts. Optimal ausforming parameters were derived to produce a high performance forging die.

Improving wear resistance of epoxy/SiC composite using a modified apparatus

A centrifugal mixing method was developed to disperse ceramic particles inside a thermosetting polymer. Horizontal centrifugal equipment was used to fabricate cylindrical rods from epoxy reinforced with silicon carbide particles. Silicon carbide particles (SiC) are used for the outer coating of epoxy to increase wear resistance. In the centrifugal mixing process, there are three important variables: rotational speed, ceramic percentage and, ceramic size which affect ceramic particle distribution. This paper aims to find the relationship between these variables and the distribution of ceramic particles then determine the optimum conditions to get maximum wear resistance and hardness. From the experiment and analysis, it can be concluded that when mixing speed was greater than 600 rpm, the possibility of air bubbles formation was increased especially for ultrafine particles. Otherwise, the maximum wear resistance and hardness values were found in ultrafine size SiC samples reinforced with 30 wt% which were mixed at a low speed of 300 rpm.

TECHNOLOGY OF COMBINED ELECTROMECHANICAL TREATMENT WITH PROFILE ROLLING

The technology of combined electromechanical treatment with profile rolling is presented, which is a combination of electromechanical treatment and surface plastic deformation, which allows to create on the surface directed regular microrelief. The proposed technology is tested during processing of parts of multipurpose tracked and wheeled machines operating under difficult loading conditions, signalternating dynamic loads, often with limited lubricant or presence of abrasive in its composition. Reasonable selection of relief (pattern) of treated surface makes it possible to maximize retention of lubricating material in zone of tribocontact, as well as to increase wear resistance of parts and to create residual compression stresses in surface layer. The mechanical properties of the surface layer of the sample with a strengthened geometric pattern by changing the microhardness of the smoothed surface and oil pockets (channels) obtained by surface plastic deformation were examined. Electromechanical treatment by rolling the profile makes it possible to create on the surface a strengthened surface layer with naturally varying parameters with the specified regular micro-relief including oil pockets (channels) and reinforced tracks, at the same time considerable increase of wear resistance of triboscreating is provided.

Providing of Operational Properties for Gas-Turbine Engine Parts and Assemblies Using Electrospark Deposition

Article explains manufacturing capability of titanium parts reliability enhancement and life cycle enhancement by electrospark deposition using low energy discharges. Carbon electrodes used to form functional properties of parts surface layer. Alloyed carbooxide zone consist of highly dispersed structure (with particles of titanium carbide, titanium oxide, graphite), with 3-10 micron thick, and high hardness antifrictionality. Alloyed layer contain ordered phase Ti8C5, TiC, and the structure of Ti6C3,75. Parts dimensions almost do not changed after electrospark deposition with carbon electrodes. Subsequent diamond burnishing decrease friction coefficient and surface roughness. Fatigue resistance increased after healing of defects and microcracks. Local carbooxidation and burnishing used to increase wear resistance of titanium alloys.

Determination of contact temperature on cutting disc during rock destruction

During the destruction of rocks by disc cutters the question of their operation without water cooling is arising. To implement this an approach to determining the temperature of the disk cutter is considered in the article. The calculations of heating of the disc cutter with various geometric parameters (diameter, sharpening angles, blunting edge radius) and geological conditions under different cutting conditions (cutting depth) are presented. The disc cutter temperature and comparison with a critical one is given. The results allow to increase wear resistance and thereby determine the modes of operation in which forced cooling of the cutting disc is not required.

On practical application of plasma and laser hardening

Laser and plasma hardening practically do not damage the surface, so the parts after their execution are sent to the assembly without finishing machining, which reduces the complexity and logistics of the process. In conditions of dry friction hardened steel discs 45 and 40Kh increase wear resistance up to 100 times. The service life of parts strengthened by laser and plasma hardening is repeatedly increased. Laser hardening differs from plasma hardening by higher cost of equipment, therefore it is preferable in large-scale production. Plasma installation UDGZ-200, thanks to manual operation, it is possible to temper the surfaces inaccessible or inaccessible to other hardening methods. This, together with the low cost of equipment, makes plasma hardening cost-effective in conditions of single-unit and small-scale productions.