Papers by Keyword: High Speed Steel

Abstract: Sustainable material processing is the current need of machine tool industries. This paper aims to design and experimentally study the material removal rate of mild steel during dry turning using a high-speed steel single point cutting tool and a conventional lathe machine. Twenty-seven turning operations are designed using an orthogonal array experimental design method. The speed, feed and depth of cut are selected as input parameters while material removal rate is considered as quality parameter. Input parameters are varied twenty-seven times during dry turning of mild steel workpieces. Effects of input parameters are investigated to discover which one has a significant effect on material removal rate and hence to determine the dry turning conditions for mild steel. Statistical test results revealed that the depth of cut is significant than feed and speed. The F-value obtained from ANOVA result and Pareto chart are verified that depth of cut is significant on material removal rate of mild steel during dry turning

Abstract: The article describes the orthogonal turn-milling technology applied for powder high speed steels. The cutter with carbide inserts was used in the experiments. The orthogonal turn-milling model was developed to improve the surface quality by choosing optimal cutting modes based on the simulation results. The mathematical model makes it possible to predict geometric surface deviations. The impact of cutting speed, tool feed and radial depth of cut on the geometric surface parameters was identified. The results make it possible to achieve the satisfactory level of surface quality without deteriorating the machining productivity. The avenues for further research are outlined.

Abstract: A matrix type high speed steel YXR3 designed for a combination of wear resistance and toughness is investigated for its mechanical properties after hardening by deep cryogenic treatment follow by tempering. The deep cryogenic quenching carried out at -200 °C for 36 hours and the single step tempering results in an obvious improvement in wear resistance while balancing the toughness, comparing with the conventional quenching followed by a double tempering treatment. The quantitative image analysis reveals little difference in the MC carbide size distribution between tempering at different temperatures. The synchrotron high energy XRD confirms the MC type carbide with some evolution in its orientation together with tempered martensite approaching the BCC structure at higher temperatures. In contrary to the conventional quenching and tempering, the lowest tempering temperature at 200 °C yields a moderate drop in hardness with increase in surface toughness proportionally while exhibiting exceptional wear resistance. Such thermal cycle can be recommended for the industry both for the practicality and improved tool life.

Abstract: In the Metal Market, it has been important to understand the structure of steels, so that it is possible to develop new cutting materials at lower costs and more resistant to high temperatures and wear. This is possible by raising the mechanical strength for solid solution in fast steels, ie, addition of alloying elements to the steel in its solid state, the alloys fundamental to this process were: cobalt, manganese, silicon, tungsten and vanadium. Among the thermal treatments, tempering and quenching were used to raise the degree of hardness and strength of the steel. The samples studied were high speed steels HS6-5-3, HS6-5-3-5, K190 e K390. Hardness and metallographic tests were carried out on the samples and with the results generated, it was possible to draw a comparison and understand which alloying elements provide the least oxidation, corrosion and greater impact strength of fast steel.

Abstract: The paper studies the surface structure and microhardness of the coating modified by the pulsed laser irradiation. The coating is obtained by plasma-jet hard-facing of the AISI (American Iron and Steel Institute) М2 high speed steel powder. The modes of the laser irradiation differ in peaking capacity, pulse duration and diameters of the focused laser beam. It is demonstrated that the weld penetration shape factor depends on the laser beam fluence and the pulse duration. In its turn, the weld penetration shape factor effects the quality of obtained irradiation zones.

Abstract: Powder metallurgical high speed steel (such as S390) has superior mechanical properties and been used as fineblanking tools. The electrical discharge machining has been widely used for cutting fine blanking tools which are made of especially hard tool steels. Whereas, its thermal nature causes great concerns regarding surface integrity, which matters a lot to tool life. In the present study, the evolution of surface integrity of the S390 with multi-cutting is comprehensively compared. The result shows that the surface roughness, white layer thickness and surface residual stress decrease with the increase of cutting pass. Additionally, the effectiveness to remove white layer on HSS S390 by manual and towed polishing and electrolytic polishing are compared. At last, a device of abrasive water jet polishing is designated to remove the white layer resulted from wire-cutting.

Abstract: Hot strip rolling process is one of the most promising industrial processes to fabricate finished or semi-finished bulk products. Numerical analysis on the temperature and thermal stress distributions in a high speed steel work roll during hot rolling has been conducted based on a transient thermo-mechanical model. Influence of initial work roll body temperature on temperature and thermal stress has been discussed in detail by assuming different rolling stages. Compared to the work roll surface, stress is much smaller at depth of 2.1 mm and 5.0 mm, respectively. Results showed similar maximum circumferential thermal stress at both depths of 2.1 mm and 5.0 mm when the roll has initial temperature of 25 °C and 100 °C, but they are about 3 times and 8 times larger than at depth of 2.1 mm and 5.0 mm, respectively, when the initial temperature is 200 °C.

Abstract: This work aimed to evaluate the effect of pre-sintering annealing heat treatments and sintering times in AISI M2 high-speed steel powders processed by high energy milling. Turning chips were obtained from an AISI M2 drill bit that was annealed during 2 hours at 900°C, under argon atmosphere, before machining. Subsequently, the chips were milled during 10 hours in a high energy planetary mill with a power ratio of 10:1, also under argon atmosphere. Half of the powder mass was annealed at 650oC during 30 minutes under argon atmosphere after milling. Three different samples were prepared, consisting of: non-annealed powder, annealed powder and a mixture 1:1 of annealed and non-annealed powders. All powders were compacted by uniaxial pressing before sintered. Compressibility curves were obtained for all samples. Sintering process was conducted at 1200°C during 1, 2 and 3 hours and samples were cooled inside the furnace. The annealed powder sample presented the best compactation behavior, due to its restored ductility, followed by the 1:1 mixture of annealed and non-annealed powders. The microstructure of sintered samples displayed a ferritic matrix surrounded by carbide networks at grain boundaries. Higher sintering times resulted in carbon impoverishing, leading to lower volume fractions of carbides and hence reducing its hardness. Non-annealed powders showed higher dependency of sintering time to reduce their porosity. The best results were obtained for the annealed powder with shorter sintering time, since it presented low volume fraction of porosities and smaller grain sizes.

Abstract: The main aim of this work was to study the behavior of the secondary hardening of AISI M3:2 high speed steel named Sinter 23^® produced by powder metallurgy process of hot isostatic pressing (HIP). The M3:2 high speed steel Sinter 23^® was submitted to heat treatment of hardening with austenitizing temperatures of 1140 oC, 1160 oC, 1180 oC and 1200 oC and tempering at 540 oC, 560 oC and finally 580 oC. The effectiveness and response of the heat treatment was determined using hardness tests (Vickers and Rockwell C hardness) and had its property of secondary hardness evaluated. The results showed that the secondary hardening peak of Sinter 23^® high speed steel (tempering temperature at which maximum hardness is attained) is at 540 °C for the lower austenitization temperatures of 1140 °C and 1160 °C, and it is at 560 °C for the higher austenitizing/quenching temperatures of 1180 °C and 1200°C.

Abstract: The phase composition, microstructure and morphology of composite powders «TiC-HSS steel binder» obtained by the SHS method in layerwise combustion mode have been studied. Titanium powder, carbon (carbon black) in a ratio corresponding to equiatomic titanium carbide and high speed steel as a thermally inert binder was used as a reaction mixture. It was found that the mass transfer of reaction mixture components between the carbide and metal binder was taking place during synthesis, as a result of which the final phase and elemental composition of the synthesis products was formed. It is shown that the volume content of thermally inert binder significantly affects the dispersion of the formed carbide phase.