Papers by Keyword: High-Speed Steel

Abstract: The present investigation has been carried out to study the microstructure evolution and microhardness of the multi-component B–C–N diffusion coatings developed on wrought AISI M2 high-speed steel substrate at 560 and 650 °C for 1 and 4 h for both temperatures. The microstructure of the coatings was studied using scanning electron microscopy, energy dispersion spectroscopy and X-ray diffraction analysis. Vickers microhardness measurements were also performed. The investigations showed that varying conditions of the thermochemical treatment resulted in a variety of coatings which exhibited varying microstructure, phase composition and microhardness.

Abstract: The high-temperature deformation behavior and microstructural changes of harmonic structure composites with WC-Co alloys and high-speed steel (HSS) were investigated in detail. A harmonic structure composite was fabricated by consolidating the mechanically milled powder having WC-Co and HSS powder. The harmonic structure composite demonstrates the microstructure composed of network area (WC-Co) and dispersed area (HSS). The harmonic structure composite shows a sufficient compressive strength in the compression tests at 773 K, but the compression strength decreases at temperatures of above 873 K. The 0.2% proof stress at high temperature almost unchanged even if the network area fraction changed. Furthermore, the network area plays an important role in the high temperature deformation of harmonic structure composites. These results suggest that the formation of voids for WC-Co boundary sliding and poor sintering is an important factor in stress reduction in the high-temperature compression of harmonic structure composites.

Abstract: The present study has been undertaken to study the microstructure and microhardness of the multi-component B–C–N diffusion coatings developed on AISI M2 high-speed steel substrate at 560 and 650 oC for 1 and 4 h for each temperature respectively. The investigation of the coatings was fulfilled using scanning electron microscopy, energy dispersion spectroscopy and X-ray diffraction analysis. Additionally, Vickers microhardness measurements were performed. The results showed that varying conditions of the thermochemical treatment led to a variety of coatings in the sense of their microstructure and phase composition.

Abstract: Despite the advanced development in the field of creating new hard-alloy and ceramic tool materials, the use of modern high-speed steels has not yet lost its relevance, and it is especially true for the production of small batches of costly specialized tools, especially since modern strengthening technologies can make it competitive. For example, additive production systems associated with laser or electron beam manufacturing methods create products, including Ti-6Al-4V alloy, with low surface quality, and it is still necessary to apply the additional cutting treatment. The features of milling titanium alloy obtained by the electron beam melting method were revealed. It is determined that the force parameters differ from those in the processing of metal obtained by traditional technologies. Thus, the component of cutting tangential force F_T increases by approximately 15%. At the same time, a 20% drop in the radial force F_R observed

Abstract: The present study has been undertaken to replace W by Cr in as-cast HSSs using B as alloying element. For this reason, a special alloying system was suggested. The basic steel containing approximately 12 wt. % of Cr was alloyed with B, V, V and Mo in different proportions. The microstructure of the steels was studied using electron microscopy, X-ray diffraction, and energy dispersive X-ray analysis. It was shown that the matrix structure, as well as the origin and morphology of the carbides or carboborides formed during solidification greatly depended on the alloy chemical composition.

Abstract: The influence of annealing at 1200 °C for 2, 4 and 8 h on the carbide microstructure of AISI M2 type high-speed steel obtained by both the foundry and conventional metallurgy technologies has been studied. The primary focus was on the kinetics of eutectic carbide decomposition and dissolution in both the cast and wrought M2 high-speed steels under the effect of high temperature.

Abstract: The method of imparting ultrasonic vibration to the cutting tool is known to improve the shape accuracy and finished surface roughness. However, a uniform evaluation of this function in drilling has not been achieved, and the cutting process cannot be checked from the outside. The aim of this study is to investigate the cutting characteristics in deep hole drilling when an ultrasonic vibrator on the table of a machining center provides vibration with a frequency of 20 kHz to the work piece. The ultrasonic vibrations in this system reach the maximum amplitude in the center of the work material. We evaluated the change in finished surface roughness between the section where drilling starts to the point of maximum amplitude with ultrasonic vibration. The main cutting conditions are as follows: cutting speed (V) 12.6 (mm/min); feed rate (s) 30, 60 (mm/rev); depth of cut (t) = 32 (mm); work material, tool steel; cutting tool material, HSS; point angle (σ) 118 (°); and drill diameter (φ) 4 (mm). Lubricant powder was also added to clarify the cutting effect, and compared the condition in which there was no ultrasonic vibration. The results showed that surface roughness at the point of maximum amplitude was better than that with no vibration.

Abstract: In this study High-speed steel taps are taken as the research object. Electrolysis technology was used to deal with the taps in various count time (7s 14s 21s 28s 35s) and then obtain the corresponding radii of the cutting edge (11.38μm 15.05μm 20.35μm 23.00μm 25.55μm). The experimental results exhibit quantitatively the effect of tool radius on the performance of tapping. A radius on the cutting edge prevents fast and unpredictable wear. Moreover, the existence of an optimum value of the radius has been revealed experimentally. Tapping test is used to prove the optimal cutting edge radius is 15.05μm and the taps life increase about 2.5 times than usual taps. It can provide an important theoretical basis for the modifications of the cutting edge radius and give a method to improve tap life.

Abstract: The influence of heat treatments on the microstructure of AISI M2 type high-speed steel obtained using conventional metallurgy has been studied. The primary focus was on the effects of austenitisation temperatures on the behaviour of the initial eutectic carbides during austenitisation. In order to investigate kinetics of both the microstructure and phase transformations in eutectic carbides upon heat treatments with respect to diffusion processes, different techniques of electron scanning microscopy and energy dispersive X-ray spectrometry have been used. The effect of the austenitisation temperature on the primary austenite grain size, martensite microstructure and volume fraction, size distribution, and morphology of the primary carbides of eutectic origin as well as their behaviour during heat treatment in the wrought M2 high-speed steel was thoroughly investigated.

Abstract: High-speed steels are successfully manufactured to make work rolls in hot rolling steel mills. An understanding of their oxidation behaviour is crucial to the degradation of work rolls and the surface quality of rolled strip. In this paper, the high temperature oxidation behaviour of a work roll with high-speed steel material was investigated under isothermal conditions from 550 to 750 °C for 30 min in 20% humid air. The results indicate that molybdenum-rich carbides M₂C are oxidised and protrude out of the surface, vanadium-rich carbides MC and iron and chromium-rich carbides are easily identified and less influenced, but the oxides grown on the matrix are relatively even at 550 and 600 °C. However, at higher temperature, MC carbides are severely oxidised and extend to their nearby areas, whereas M₇C₃ zones can still be recognised but with more small particles grown on them.