Production Of High-speed Steel Research Articles

Identifying the features of structural and phase transformations during the processing of oxide waste from the production of high-speed steel

Peculiarities of phase and structural transformations during the carbon-thermal recovery of high-speed steel slag with the production of an alloying additive were investigated. This is necessary to determine the technological indicators that allow reducing the loss of high-value elements during the production and use of the alloying additive. A gradual change in the degree of scale reduction from 32 % to 69 % and 77 % led to an increase in the appearance of the solid solution of alloying elements and carbon in the α-Fe lattice with respect to FeWO4 and Fe3O4. Along with this, Fe3C, FeW3C, WC, VC, V2C, and Cr3C2 were manifested. At the same time, the formation of polyhedral and rounded particles of different chemical composition and the formation of a spongy microstructure was observed. It was determined that the most acceptable degree of recovery is 77 %. At the same time, the degree of reduction of 69 % is also sufficient since due to the residual carbon in the form of carbides, an increased reduction capacity is ensured with additional reduction of the oxide component in the liquid metal during alloying. The spongy microstructure provides relatively fast dissolution compared to standard ferroalloys, which causes a reduction in the total melting time while reducing the resources spent. No phases and compounds characterized by an increased tendency to sublimation were detected in the obtained alloying additive. That is, there is no need to provide additional conditions that prevent the loss of high-value elements during evaporation with the gas phase, which causes an increase in the degree of extraction of alloying elements. The indicators of the obtained alloying additive make it possible to melt alloyed steel in an electric arc furnace with respect to brands whose composition does not have strict restrictions on carbon, while replacing a part of standard ferroalloys.

Unknown high-speed steel

High-speed steels (HSSs) and their heat treatments have very long history. However, in the literature it is possible to come across some misunderstandings primarily in relation to the heat treatments of these steels. To prevent that the objective of the current paper is to describe basic processing technologies used in the production of HSSs with special emphasis on the corresponding microstructural states.

Preparation and Characterization of Spray Formed 2060 High Speed Steel

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.

Resource- and energy-conserving low-silicon alloys in the production of high-speed steel

X-ray microanalysis is used to investigate the phase composition and microstructure of waste-based alloys with relatively low silicon content, which are intended for use in the production of high-speed steel. Possible reactions and phase transformations at all stages of refining are studied. The physicomechanical properties of the alloy are established. Guidelines are proposed for reducing waste and increasing the assimilation of alloying elements by the steel melt.

Spray forming high speed steel—properties and processing

The potential of spray forming (SF) for microstructural refining can be attractive to the production of high speed steels. The refined as-cast structure may lead to important improvements of material properties, compared to conventionally cast materials. The present work aimed to compare the properties of AISI M3:2 high speed steel produced through spray forming and conventional casting. Also, the processing of SF billet is considered, specifically the hot working conditions and its relation to carbide size. A round 400 mm diameter SF billet was produced using a twin atomiser. Characterisation was performed in the as-cast structure and after hot working to 116 mm squared bars and 11 mm diameter round bars. The results show that, compared to conventionally cast high speed steel, the SF material has higher isotropy in toughness due to its less oriented carbide distribution. Regarding processing procedures, time and temperature employed in heating before hot working also affect the microstructure of SF material.

Possibility of using atomized powders for the production of high-speed steel from compactible mixtures

1. An investigation has shown that porous high-speed steel articles can be successfully produced by pressing and sintering from mixtures of an atomized steel powder and a reduced ferrotungsten powder. 2. Sintering in a vacuum corresponding to not more than 5·10−5 mm Hg ensures the necessary conditions for the dissolution of the atomized high-speed steel powder particles in the ferrotungsten at temperatures in the range 1000–1200°C.

Production of high-speed steel by the powder metallurgy technique

Production of high-speed steel by the powder metallurgy technique

Size of excess carbides in high-speed steels

1. The number of large carbides (over 9 μ), commensurate with the radius of curvature of the cutting edge, increases with the weight of the ingot, especially in the case of high-tungsten steel R18, which is the result of the solidification conditions. 2. Reducing the tungsten content and adding molybdenum induce refining of the carbides. In deformed tungsten-molybdenum steel R6M5 the number of large carbides is only half that in steel R18. Nevertheless, the number of large carbides remains substantial in steel R6M5 obtained from large ingots (550 kg and larger). 3. The degree of deformation, which has a large effect on the distribution of carbides (carbide heterogeneity), has almost no effect on the size of carbides. 4. For the production of high-speed steels rolled to small sections (diameter up to 20 mm) it is recommended that the ingot weigh 100–150 kg.

Methods of cold pressing powder mixtures for the production of high-speed steels

Methods of cold pressing powder mixtures for the production of high-speed steels