Properties Of High-speed Steels Research Articles

Methods of Improving the Structure and Properties of High-Speed Steels

Methods of Improving the Structure and Properties of High-Speed Steels

Influence mechanism of Y addition on microstructure, adsorbability, mechanical properties of as-cast high speed steel

To improve the mechanical properties of high speed steels (HSSs), different contents of rare earth Y (0, 0.047, 0.096, 0.229, and 0.310 (wt.%)) are added, and the microstructure and mechanical properties of as-cast HSSs are systematically studied. The results show that the phases of HSSs are mainly composed of α-Fe, MC, M2C, and M6C (M = Fe, V, Cr, etc.). The Y element is primarily distributed at the interface between carbide and matrix. The morphology of carbide changes remarkedly with the increased Y content, i.e. the shape factor K of carbide increases from 0.3154 to 0.4028. Moreover, as the Y content increases from 0 wt% to 0.229 wt%, the strength, elongation and impact toughness of HSSs are improved from 516.7 MPa, 0.29% and 3.8 J to 820.9 MPa, 0.47% and 5.2 J, respectively. This provides a new idea for the design and application of HSSs, and has a practical reference value for the development of other wear-resistant materials.

Influence of heat treatment parameters on effectiveness of deep cryogenic treatment on properties of high-speed steels

This study investigates the influence of heat treatment parameters on effectiveness of deep cryogenic treatment (DCT) and on properties of three high-speed steels (HSS) (AISI M2, AISI M3:2 and AISI M35) with different chemical composition. Within this research the same preselected soaking temperature, time, cooling/warming rate and placement of DCT, being found in the literature as the most effective, were applied to the selected HSS grades. The fatigue resistance, hardness, impact and fracture toughness, compressive strength and strain-hardening exponent were selected as the evaluators of DCT effectiveness. The results indicate that the influence and effectiveness of DCT is strongly subjected by the type (wrought or PM steel), chemical composition of the particular steel grade and heat treatment parameters, resulting in either degradation or improvement of the steel properties. Furthermore, the study elucidates the effect of DCT on different HSS grades based on the selected heat treatment temperatures (austenitization and tempering). The research confirms that DCT generally improves the hardness, fatigue properties, fracture and impact toughness, compressive strength and strain-hardening exponent for HSS grades. However, it may also have negative impact on HSS properties. For all HSS investigated, the level of DCT effect depended also on the heat treatment conditions, i.e. austenitization and tempering temperature. The lower austenitization and higher tempering temperature in general resulted in improvement of steel properties, as compared to higher austenitization and lower tempering temperature with predominantly negative effect.

Effects of alloying elements with various heat treatment processes on the properties of high speed steels

Effects of alloying elements with various heat treatment processes on the properties of high speed steels

High Speed Steel with Iron Addition Materials Sintered by Spark Plasma Sintering

Attempts were made to describe the effect of the sintering temperature and pure iron powder addition on the properties of high speed steel based materials produced by the spark plasma sintering technique. After sintering, their density, hardness, flexural strength, and tribological properties were determined. The sintered materials were also subjected to microstructural analysis in order to determine the phenomena occurring at the particle contact boundaries during sintering. Based on the analysis of the obtained results, it was found that the mechanical properties and microstructure were mainly influenced by the sintering temperature. Using the temperature of 1000 °C allowed materials with a density close to the theoretical density to be obtained, characterized by a high hardness of about 360 HB and a low wear rate of about 1E-07 g/s.

Cutting performance of deep cryogenic treated and nitrided HSS cutting tool inserts

High speed steel (HSS) is a very important industrial tool material and has been constantly improved for different wear resistance applications and cutting tools, i.e. drills, milling cutters, hobs and for the cutting tools in which the economical cutting speed is too low for choosing the carbide tools. The properties of HSS depend significantly on the parameters of the conducted heat treatment. In this paper, the influence of deep cryogenic treatment in combination with nitriding of metallurgical powder metallurgy HSS on the wear resistance was measured. Additionally, the cutting performance in a single point cutting tool machinability test at the configuration of the dry low-speed turning of steel was investigated. The results showed that deep cryogenic treatment itself, and in combination with nitriding, resulted in the reduction of the wear rate. The results of the single point cutting tool machinability test showed that deep cryogenic treated and nitrided HSS inserts performed worse than the classically heat-treated inserts and deep cryogenic treated HSS inserts exhibited approximately the same flank wear as the nitrided ones.

The effect of amorphous nanocrystalline inoculants on structures and properties of high speed steel

High speed steel (HSS) is widely used in the production of high-speed cutting tools and roll etc, and the modification method is an effective approach for improving the microstructure and properties of HSS. Fe–Al–Cr–Nb–C–N amorphous nanocrystalline inoculants were fabricated using the method of in situ reaction and rapid solidification. The phase compositions of Fe–Al–Cr–Nb–C–N inoculants were analyzed. And the effect of inoculants on structures and properties of AISI T1 HSS was studied. The results show that the inoculant is a mixture of amorphous and nanometer crystal, and Fe–Al(–Cr) intermetallic compounds are the matrix phases of inoculant, while particulate nitride, carbide and oxide are the important precipitation. After modification, the quenching and tempering microstructure of HSS has been refined significantly. The carbides contents increase and the sizes of carbides decrease in HSS. The hardness, red-hardness, wear resistance and impact toughness of T1 HSS were also improved obviously after modification.

Effect of heat treatment conditions on structure and properties of high-speed steel

High-speed steels made by powder and traditional metallurgical technology have been investigated. These steels are used for manufacturing of metalworking tools. Powder high-speed steels have a large safety margin and a high level of mechanical properties. Mechanical properties and the structure of steels S390 MICROCLEAN® and Fe-9%W-4%Mo-8%Co were compared after their hardening heat treatment. The composition of the carbides was determined by x-ray phase analysis. Residual stresses of the finished cutters were determined. It was shown that the mechanical properties of steels have been determined by the phase composition and the degree of carbides dispersion. The dependence of the microstructure and the high-speed steels phase composition on heat treatment conditions was identified. The conclusion about structure control effectiveness in the adjustment of heat treatment conditions of high speed steels was made.

Оценка трибоэлектрических характеристик быстрорежущих сталей

Оценка трибоэлектрических характеристик быстрорежущих сталей

Effect of Mischmetal on As-cast Microstructure and Mechanical Properties of M2 High Speed Steel

High speed steel has been widely used in various fields due to their excellent red hardness and good wear resistance. However, the influence of mischmetal (Ce-La) on the as-cast microstructures and mechanical properties of high speed steel has rarely been reported. Thus, the microstructure and mechanical properties of M2 high speed steel with addition of mischmetal (Ce-La) were investigated. The morphology and distribution of the eutectic carbides of the steel were observed by using optical microscopy and scanning electron microscopy, and the impact toughness and bending strength were tested. The results show that adding mischmetal has an obvious effect on the microstructure and mechanical properties of M2 high speed steel. The coarse eutectic structure is refined, the weak connection of the carbide networks is broken and the flake carbides become short and fine. More networks of eutectic carbides dissolve into the matrix. When a suitable adding content of mischmetal is selected, for example, 0.3 mass%, the impact strength and bending strength can increase by 27% and 10.76% compared with that without mischmetal, respectively.

Microstructural Characterization of Ni Based Cladding on SS-304 Developed through Microwave Energy

In the present work microwave cladding technique was progressed for enhancement of surface properties of high speed steel (SS-304). The experiments were conducted in domestic microwave oven with the help of Al2O3 shield. The clad of thickness, approximately 1mm was developed by microwave exposure at frequency 2.45GHz. The entire setup was exposed to microwave environment for about 1080s.The developed clads were characterized using FE-SEM, EDS, XRD and measurement of Vicker's microhardness. Microstructural study reveals that there is a metallurgical bond with SS-304 substrate & partial diffusion of constituent elements. Chromium was observed segregated around the cell boundaries while iron and nickel were identified inside the cells.

高速钢表面激光熔覆Al2O3条纹的摩擦磨损性能研究

高速钢表面激光熔覆Al₂O₃条纹的摩擦磨损性能研究

The investigation of Microstructures and Properties of High Speed Steel HS6-5-2-5 after Laser Alloying

W pracy przedstawiono wyniki badań laserowego stopowania na strukturę i własności warstwy wierzchniej stali szybkotnącej HS6-5-2-5, przetapianej za pomocą lasera diodowego dużej mocy (HPDL). Jako materiał stopujący użyto proszków WC, VC, TiC, SiC, Si3N4 i AI2O3. Stwierdzono, że do przetopienia i stopowanie laserowe twardymi cząstkami powoduje poprawę własności warstwy wierzchniej w całym zakresie mocy lasera. Odpowiedni dobór warunków pracy lasera jak również jakość wiązki ma wpływ na wyniki przetopienia co potwierdzono badaniami twardości, mikrotwardości, mikroanalizy rentgenowskiej i rentgenowskie analizy fazowej. W strefie przetopionej i stopowanej stwierdzono występowanie drobnoziarnistej oraz dendrytycznej struktury z kierunkiem krystalizacji związanym z dynamicznym przepływem ciepła ze strefy oddziaływania wiązki laserowej. Drobnoziarnista struktura martenzytu jest odpowiedzialna za wzrost twardości warstwy stopowanej. Zmiany mikrotwardości ściśle zależą od efektów oddziaływania wiązki laserowej na obrabianą powierzchnię. Wyniki badań pozwalają na lepsze zrozumienie mechanizmów strukturalnych towarzyszących przetapianiu i stopowaniu laserowemu. Laserowa obróbka powierzchniowa stanowi szczególnie obiecujące narzędzie do rozwiązywania problemów inżynierii powierzchni dzięki wykorzystaniu własności fizycznych wiązki lasera umożliwiających precyzyjną obróbkę cieplną w warstwie wierzchniej.

The effects of AlCrN coating, surface modification and their combination on the tribological properties of high speed steel under dry conditions

In this study, the effects of a combination of ultrasonic nanocrystalline surface modification (UNSM) technique and AlCrN coating on the tribological properties of high speed steel (HSS) were investigated. The AlCrN coating with a thickness of about 3µm was deposited by the physical vapor deposition (PVD) technique onto the polished and UNSM-treated HSS specimens. The tribological and scratch tests results revealed that the AlCrN coating deposited onto the UNSM-treated specimen showed better tribological properties compared to that of the AlCrN coating deposited onto the polished specimen, which may be attributed to the modified surface beneath the AlCrN coating. Hence, it is expected that the results of this study can be applied to reduce the wear of fine blanking punches.

Abnormal grain growth in high speed steels

The combination of the chemical composition and a specific heat treatment consisting of austenitising close to solidus temperature and subsequent triple tempering leads to the excellent properties of high speed steels. Usually when high speed steels are heated up to austenitising temperature, intermediate holding stages and specific heating rates are applied. This specific heat treatment affects the microstructure, especially the grain size distribution. In some cases, abnormal grain growth can occur. This study describes the influence of the variation of the parameters, such as intermediate holding temperature and heating rate on the microstructural development. All investigations were carried out on the high speed steel HS 6-5-2-5 using both laboratory tests and vacuum heat treating.

Effect of Ti Addition on the Microstructure and Properties of a High Speed Steel Roll

Abstract In the present work, the effect of Ti addition on microstructure and properties of high speed steel (HSS) used for rolls was investigated utilizing optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy spectrum analysis. The results indicated that as-cast microstructure of the HSS roll is mainly composed of MC, M2C and M7C3 eutectic carbides and metallic matrix consishing of a mixture of martensite, austenite, and pearlite. The carbides are connected or placed next to each other to form a network along grain boundaries. The addition of 0.5 wt.-% Ti leads to a great change in the morphology, size and distribution of carbides. The carbide network tends to break, and all carbides are refined and distributed homogeneously in the matrix. After normalizing treatment at 1050 °C, the carbides in the Ti containing HSS roll transform into granular or nodular distribution. The mechanical properties, thermal fatigue, and wear resistance of Ti containing HSS roll are more excellent than that of the HSS roll without titanium.

Effects of Electrolyte Plasma Carbonitriding on Tribological Properties of High Speed Steel

This paper presents research of influence electrolyte plasma carbonitriding on tribological properties of R6M5 high-speed steel. Shows perspectiveness of carbonitriding high-speed steels in electrolyte plasma. The results of research demonstrated increasing wear-resistance of R6M5 steel after carbonitriding in electrolyte plasma. Under the same test conditions by the method of scratch-test have been determined that the depth of the scar of a modified layer has become less in comparison with the original sample, which indicates a significant increase of wear-resistance and hardness of the surface carbonitriding layer R6М5 steel. It was set that after electrolytic-plasma carbonitriding abrasive wear-resistance of the surface layers of R6M5 steel is increased by 25%. Introduction

Effect of Electromagnetic Stirring on the Microstructure and Mechanical Properties of the High Speed Steel

In order to improve the microstructure and mechanical properties of High Speed Steel (HSS), electromagnetic stirring method is adopted to enhance the solidification of target materials in this paper. The results show that optimization of the microstructure, refinement of the grain, reducing in segregation of the alloy elements, and improvement of the comprehensive properties of HSS can be obtained by the electromagnetic stirring through changing the morphology and distribution of the carbide.

Effects of Co as an Alloying Element and Heat Treatment Processes on the Properties of High Speed Steels

Abstract In this study, effects of Co as an alloying element and different heat treatments processes on the properties of DIN 1.3243 and 1.3343 were investigated. Austenitising and tempering temperatures are critical parameters for steel hardening. Also, Co has critical effect on mechanical properties of high speed steels. Samples were subjected to two different austenitising temperatures with two tempering temperatures. Effects of process parameters on the mechanical properties and tooling abilities of the specimens were investigated. Specimens were characterized by Rockwell hardness tests and tooling abilities of the specimen were determined by characterizing the number of screws that were fabricated with specimens. According to results of experiments, Co has any effect on the hardness of specimens after the austenitising and tempering processes. Moreover, tool life of the specimens were increased by the higher hardening temperatures, the lower tempering temperatures and the presence of Co as an alloying element, because of the positive effect of Co on the hot hardness and hot strength.

Modification of the structure and properties of high-speed steel by combined vacuum-plasma treatment

Modification of the surface of a cutting tool from steel R6M5 by the method of vacuum-plasma treatment including ion nitriding in gas plasma and deposition of a wear-resistant (Ti, Al)N coating in the metal-gas plasma of vacuum-arc discharge is studied. Regular features of formation of nitrided layer are determined and optimization of its structure for various operating conditions of the cutting tool is performed. Modes of vacuum- arc treatment providing the lowest intensity of wear of the tool in the process of cutting are determined.