Performance Of High Speed Steel Research Articles

Characteristic analysis of high-speed steel powder prepared by gas atomisation

The performance of high-speed steel (HSS) powder is a prerequisite for the preparation of high-performance powder metallurgy HSS. The physical properties, microstructure, and solidification characteristics of HSS powder prepared by nitrogen gas atomisation were systematically studied and analysed in detail. For the atomised TPM558 HSS powder, the morphology is spherical and the particle size distribution is wide. The smooth small particles of satellite powder attach to the surface of large particles. Shrinkage pits caused by solidification shrinkage exist on the surface of large particles. The average cooling rate is between 104 and 106 K·s−1, with the increase of cooling rate, the powder surface tends to be smooth, and the grain structure is transformed in the order of cellular to dendritic to radial. The single powder particle surface shows fine-equiaxed grains, while the internal presents columnar grains. The crystalline phases of the powder are austenite, ferrite, martensite, and carbide, and the carbide includes MC carbide with face-centred structure and M2C carbide with hexagonal structure. The average nano-hardness of the powder is 9.93 GPa, resulting in poor formability, and it can be pressed and formed only after adding binder.

The Evaluation of PVD Coated High Speed Steel End Mill

To enhance the cutting performance of high speed steel(HSS) end mill, single and multilayer coating is applied on the substrated of the HSS end mill. Coating material reduces cutting force and enhances resistance against abrasive wear. This paper presents the physical vapour deposition(PVD) coating technology and the machinability of PVD coated HSS end mill. The performance of coated HSS end mills are fifteen times better than uncoated HSS end mill on proposed cutting conditions. The TiAlN monolayer coated end mills(futura nano coating) are better than those of multilayer coated end mills(futura coating) on machined surface and tool wear.

Optimization of Induction Quenching Processes for HSS Roll Based on MMPT Model

To improve the comprehensive performance of high speed steel (HSS) cold rolls, the induction hardening processes were analyzed by numerical simulation and experimental research. Firstly, a modified martensitic phase transformation (MMPT) model of the tested steel under stress constraints was established. Then, the MMPT model was fed into DEFORM to simulate the induction quenching processes of working rolls based on an orthogonal test design and the optimal dual frequency of the induction quenching process was obtained. The results indicate that the depth of the roll’s hardened layer increases by 32.5% and the axial residual tensile stress also becomes acceptable under the optimized process. This study provides guidance for studying phase transformation laws under stress constraints and the optimization of complex processes in an efficient manner.

Corrosion Inhibition of High Speed Steel by Biopolymer HPMC Derivatives.

The corrosion inhibition characteristics of the derivatives of biopolymer hydroxypropyl methylcellulose (HPMC), hydroxypropyl methylcellulose phthalate (HPMCP), and hydroxypropyl methylcellulose acetate succinate (HPMCAS) film are investigated. Based on electrochemical impedance spectroscopic measurements and potentiodynamic polarization, the corrosion inhibition performance of high speed steel coated with HPMC derivatives is evaluated. The Nyquist plot and Tafel polarization demonstrate promising anti-corrosion performance of HPMC and HPMCP. With increasing film thickness, both materials reveal improvement in corrosion inhibition. Moreover, because of a hydrophobic surface and lower moisture content, HPMCP shows better anti-corrosion performance than HPMCAS. The study is of certain importance for designing green corrosion inhibitors of high speed steel surfaces by the use of biopolymer derivatives.

Effect of cryogenic and QPQ compound treatment on the microstructures and performance of high speed steel

China’s High-speed steel cutting tools hold a considerable share in the global market. However, the overproduction of low-end HSS tools causes serious resource waste and low efficiency, which has become one of the major problems in the tool industry in China. So a new Surface Modification technology is developed, which can make the low-end HSS tools into the high-end ones. On the analysis of the mechanism of cryogenic and quenching-polish-quenching(QPQ), the cryogenic and QPQ compound treatment are studied by using ϕ8 HSS(M2) drills. The nitriding layer and the base of the drill bit are Studied and analyzed, and the mechanism of compound treatment is discussed by the technological parameters adjustment and the combination test of cryogenic, nitrogen, tempering procedures, and several analysis methods such as the optics metallographic microscope, the scanning electronic microscope (SEM), X-ray diffraction and micro hardness. The cutting test is done on the drills by cryogenic treatment, QPQ treatment and cryogenic and QPQ compound treatment separately. The results indicates that the cutting life of HSS (M2) drill can be increased dramatically by cryogenic and QPQ compound treatment.

Comparison of the mechanical performance of cutting tools coated by either a TiC xN 1 − x single-layer or a TiC/TiC 0.5N 0.5/TiN multilayer using the hollow cathode discharge ion plating method

TiC xN 1 − x single-layer (x = 0–1.0) and TiC/TiC 0.5N 0.5/TiN multilayer coatings prepared using the hollow cathode discharge (HCD) ion plating method were investigated to improve the mechanical performance of high speed steel cutting tools. The carbon/nitrogen ratio of the TiC xN 1 − x coating was controlled by adjusting the composition of an additional acetylene/nitrogen mixture gas during the ion plating process. The mechanical performance characteristics of the coated cutting tools, such as the surface hardness, adhesion, wear and dynamic hardness, were studied. The cutting tools coated by the multilayer films showed higher wear resistance and longer use life than those coated by TiC xN 1 − x single-layer films. The higher dynamic hardness of the multilayer coatings was considered the primary contributor to the improvement of the mechanical properties.

Magnetic Field on Properties of Solid Lubricants Coating on High-Speed Steel Surface

The main factors that affect properties of solid lubricant coating on high-speed steel surface are the surface roughness and the weight of phosphate coating. The effect of magnetic field on high speed steel phosphate process is significant. It promotes the film and the different appearance and composition of the film. Because the ferric phosphate and dihydric phosphate in phosphate solution may be ordered arrangement by additional magnetic field, they can be deposited on metal surfaces quickly. That is to say that a certain intensity of the magnetic field can reduce the entropy of the phosphate processing system and speed up the formation of phosphate film. During phosphate treatment, the friction performance of high-speed steel coated with solid lubricant coating was significantly improved.

A study of segregation mechanism in centrifugal cast high speed steel rolls

Segregation influences the microstructure and performance of high speed steel (HSS) roll. The main reason why segregation occurs in centrifugal cast HSS roll is that atom clusters are formed in HSS melt and such atom clusters have different densities. The high-density atom clusters move to the outer periphery and the low-density atom clusters move to the inner periphery of the roll under centrifugal force. Changing the movement law of atom clusters in the centrifugal force field and increasing the solidification rate of HSS melt can lighten the segregation in HSS roll and improve its performance.

Effect of RE-Mg Complex Modifier on Structure and Performance of High Speed Steel Roll

The effects of rare earth (RE) and magnesium complex modifier on the structures and performance of high speed steel (HSS) roll were investigated and the mechanism of modification was analyzed by means of optical microscope (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) analysis, tensile testing machine and impact tester. The results showed that RE-Mg complex modifier could refine the grain, change carbide morphology and distribution, and increase mechanical properties. After heat treatment at 1000 °C, many networked carbides in HSS roll were broken and a number of granular carbides appeared. Most of eutectic carbides were spheroidized and distributed uniformly. The networked carbides disappeared completely after heated to 1050 °C. The reason that RE-Mg improves the microstructure of HSS roll was analyzed.

Assessing the Performance of High Speed Steel Coated Tools in High Speed and Dry Gear Hobbing

Assessing the Performance of High Speed Steel Coated Tools in High Speed and Dry Gear Hobbing

Evaluation of the wear of plasma-nitrided and TiN-coated HSS drills using conventional and Micro-PIXE techniques

The machining performance of high-speed steel (HSS) twist drills that were plasma-nitrided before applying physical vapor deposition (PVD) titanium nitride (TiN) coating was evaluated and compared with that of representative, commercially TiN-coated drills. The performance criteria were (i) the tool lives from the flank wear land measurements of the drills, and (ii) the wear features from micro particle-induced X-ray emission (Micro-PIXE), SEM and EDS examinations of two representative TiN-coated drills. The flank wear measurements indicated that the pre-nitrided drills had longer tool life than the commercial drills. The wear features of the pre-nitrided drill indicated that the TiN coating was subjected to progressive wear processes. On the other hand, the wear patterns of the commercial drill revealed that the TiN coating experienced interfacial spalling. Plasma nitriding prior to the application of the TiN coating is one explanation for the improvement in the machining performance of the pre-nitrided drills and for the observed differences in the wear mechanisms of the two types of drills.

How TiN coatings improve the performance of high speed steel cutting tools

TiN coatings deposited onto high speed steel (HSS) by physical vapour deposition have successfully been used in metal cutting applications for a number of years. Many papers have been presented which all show that TiN coatings often yield decreased wear rates and, usually, reduced friction coefficients. Although different theories are proposed in the literature (hardness theory, diffusion barrier theory, thermal barrier theory, reduced friction theory etc.), most papers have not dealt with the question of how and why TiN coatings modify the performance of HSS cutting tools. The present paper contributes to the answer of this question by (1) organizing published information about significant mechanical and chemical properties of TiN and (2) closely discussing different proposed theories and making comparisons with results from the broad spectrum of experiments (tool wear simulation testing, scratch testing in a scanning electron microscope, particle erosion testing, chip formation studies, metal cutting etc.) performed by the authors. A unique combination of sufficient adhesion to the substrate, high hot hardness, high wear resistance and an ability to improve the contact conditions at the cutting edge is concluded to be the answer. The complex interrelationships encompassed by this explanation are displayed in a flowchart. The thermal barrier function and the relatively low sliding friction coefficient of TiN are believed to be of minor importance.

On the improvement of the performance of high speed steel turning tools by tin coatings

Reactive ion plating using an arc source has been used to produce a TiN layer, 5 μm thick, on high speed steel turning tools. A comparison between the cutting edge durabilities of uncoated and coated tools when oblique turning mild steel at different cutting speeds has been carried out. Dry cutting has been used to accelerate wear which in turn has been assessed on the tool flank at different cutting speeds and fixed tool angles, feed and depth of cut. Wear curves have been plotted and Taylor equations have been derived. The results have shown that the Taylor equation for uncoated tools is TV 7.28 = 9.8 × 10 12 and that of coated tools is TV 3.34 = 4.85 × 10 7 where T is the tool durability in minutes and V is the cutting speed in metres per minute. Thus the cutting edge durability of coated tools has been found to be 4.5–5 times as much as that of uncoated tools.