Papers by Keyword: High Speed Steel

Abstract: Effect of magnetic field strength on carbide precipitation behavior in W₆Mo₅Cr₄V₃ highspeed steel during medium temperature tempering was investigated. The applied magnetic field promoted the precipitation and refinement of M₆C and MC carbides at boundaries and in the grain interior, but maximum spheroidization occurred for those M₆C carbides precipitated at boundaries, the stronger the magnetic field strength, the stronger the spheroidization effect. The high magnetic field hinders the precipitation of M₂C type carbides, and the M₂C type carbides basically disappear when applying the magnetic field.

Abstract: Spray forming has attracted considerable attention for the production of high speed steels due to its potential and priority in the microstructure refining and cost saving. In this study, high-quality large billets of 2060 high speed steel were successfully produced by spray forming process using a twin-atomizer facility. As-deposited billet was subsequently processed by hot forging, quenching in oil at 1180 °C and a triple tempering in the temperature range of 500-580 °C. The microstructures and hardness of the deposit and their subsequent development resulting from hot forging and heat treatment were investigated. This paper was designed to provide insight and have a better understanding of such a system for the steel. The results showed that the as-deposited microstructure was composed of the fine equiaxed grains with V-rich MC and W-Mo-rich M₂C carbides non-uniformly distributed along the grain boundaries and inside the grains. M₂C presented rod-like or unconnected net-shaped morphologies in the as-deposited microstructure. Following hot forging, metastable M₂C carbides were completely decomposed into refined MC and M₆C nearly spherical carbides uniformly distributed throughout the microstructure. A hardness value of 31HRC was attained for the spray deposited and hot forged samples. With increasing the tempering temperature, hardness was increased firstly and then decreased. Secondary hardening peak appeared at 540 °C for spray formed 2060 steel austenitized at 1180 °C, and the corresponding peak hardness reached 71HRC.

Abstract: The paper deals with the investigations of influence parameters of electro discharge machining (EDM) on the shape accuracy of external cylindrical surfaces machined by EDM process. A Sodick AD3L CNC electrode discharge machine was used to perform the EDM tests. In order to obtain the external cylindrical surfaces by RAM EDM copper cylindrical electrodes were used. Different machining setups and dielectric immersion modes were considered. In order to investigate the influence of the machining parameters on the investigated factors a factorial plan of experiments was considered. The preliminary experimental results highlighted the possibilities to obtain small diameter external surfaces of revolution on a ram electrical discharge machine.

Abstract: Manufacturing industries are presently using many tool materials, such as high speed steel, carbide tool and diamond tools etc. The most widely and commonly used tool in the engineering industries is high speed steel (HSS). The HSS tools are the cheapest and reliable for medium and small scale industries. In this work, the HSS single point cutting tool is taken as substrate material and coated with two different combinations of TiAlN composite coating using Physical vapour deposition (PVD) technique. Also, Tool life was calculated and compared with uncoated HSS tool. The hardness and surface roughness value for both the tools have been taken under same condition. The loss of weight in the tool after machining has been weighed using standard equipments. The differences have been closely observed with sufficient trials and find out the loss in weight in both the tools. The weight loss percentage was calculated after proper machining trials. The tool life of the Titanium Aluminium Nitride (Ti 70%, Al 25%) coated tool has been increased by 3.74 times than that of uncoated tool. The surface finish for TiAlN (Ti 70%, Al 25%) coating is better than the uncoated tool. The PVD coated tools having better performance comparing with uncoated HSS tool.

Abstract: This paper aims to study the tool life of coated and uncoated high speed steel (HSS) when machining LM6 aluminium. The experiment was carried out in dry condition with spindle speed of 5000 rpm and 6000 rpm, and feed rate of 90 mm/min and 120 mm/min. Axial and radial depth of cut remain constant at 0.5 mm and 1.0 mm, respectively during the experiment. Throughout the experiments, coated HSS showed higher tool life as compared to uncoated HSS due to the coating layer of titanium aluminium nitride (TiAlN) provides protection from rapid wear during machining. For both cutting tools, the optimum cutting parameter was recorded at 5000 rpm spindle speed, 90 mm/min feed rate, 0.5 mm axial depth of cut and 1.0 mm radial depth of cut. Some evidence of built up edge (BUE) formation were observed at most of cutting tools, showing the dominant wear mechanisms appear to be adhesive wear.

Abstract: The increasing productivity demand in machining industry has lead for fast material removal machining technique of pocket milling using different tool path strategies. This project aims to study about the effect of different tool path strategies on tool wear when machining aluminium alloy 7076. Five milling strategies were evaluated outward helical, inward helical, back and forth, offset on part one-way and offset on part zigzag. CATIA V5R19 was used to setup milling path and the machining experiments were carried out on a HAAS’ 3 axis CNC milling machine. The machining was held under wet condition with 2500 rpm cutting speed, 800 mm/min feed rate, 2 mm radial depth of cut and 2 mm axial depth of cut. The results showed that the best tool path strategies are inward helical and offset on part one-way, while the worst tool path strategy is outward helical. Failure to evacuate chip during pocket milling is the main reason to cause rapid tool wear due to temperature rise and higher contact time and area of cutting tool with the chip. Results from this experiment help to guide the machinist to perform pocket milling effectively.

Abstract: M2 steels, the typical Co-free high speed steel (HSS) possessing hardness level of 63~65 HRc, are most widely used for cutting tools. On the other hand, Co-containing HSS’s, such as M35 and M42, show a higher hardness level of 65~67 HRc and used for high quality cutting tools. In the fabrication of HSS’s, it is very important to control cleanliness and eutectic carbide structure of the ingot and it is required to increase productivity at the same time. Production of HSS ingots includes a variety of processes such as casting, electro-slag remelting (ESR), forging, blooming, and wire rod rolling processes. In the present study, electro-slag rapid remelting (ESRR) process, an advanced ESR process combined by continuous casting, was successfully employed to fabricate HSS billets of M2, M35, and M42 steels. Distribution and structure of eutectic carbides of the billets were analysed and cleanliness, hardness, and composition profile of the billets were also evaluated.

Abstract: In this paper, a detailed experimental investigation was carried on the impact of the effects of tool pin and shoulder diameter in joining the Al 63400 aluminium alloy using FSW process. Flat plates of 6 mm thickness have been selected as the base material for obtaining single butt welded joints. The tool materials used for joining these base material plates are High Speed Steel (HSS) and High Chromium High Carbon Steel (HCHCr). This paper experimentally investigates and suggests the appropriate, suitable tool material & tool geometry for producing good quality welds in joining of Al 63400 alloy using FSW process.

Abstract: Effects of sintering temperatures on the microstructure and mechanical performance of SPS M3:2 high speed steel prepared by spark plasma sintering was studied. High speed steel sintering curve of continuous heating from ambient temperature to 1200°C was estimated to analyze the sintering processes and sintering temperature range. The sintering temperature within this range was divided into groups to investigate hardness, relative density and microstructure of M3:2 high-speed steel. Strip and quadrate carbides were observed inside the equiaxed grains. SPS sintering temperature at 900°C can lead to nearly full densification with grain size smaller than 20μm. The hardness and bending strength are higher than that of the conventionally powder metallurgy fabricated ones sintered at 1270°C. However, fracture toughness of the high speed steel is lower than that of the conventional powder metallurgy steels. This can be attributed to the shape and distribution of M₆C carbides which reduce the impact toughness of high speed steels.

Abstract: New feedstock formulation for metal injection moulding (MIM) of Molybdenum High Speed Steel (M2 HSS) has been developed. The binder is a multicomponent system consisting of major binder paraffin wax (PW), stearic acid (SA) and minor binder polyethelene waste rubber (PEWR). Injection moulding was conducted successfully using a powder loading of 0.65. Scanning electron micrograph of the green injection moulded part revealed homogenous distribution of the M2 HSS particles in the wax matrix. Paraffin wax and stearic acid were driven off by immersing the injection moulded part into n-heptane for five hours. Vacuum sintering of the brown parts at a temperature range of 1240°C-1280°C resulted in high quality M2 HSS parts. The properties of the sintered part such as physical, mechanical and microstructure were studied and discussed to evaluate the influence of waste rubber in MIM of M2 HSS.