Janusz Richter

Characterization of carbide phase in nonledeburitic high-speed steel containing Ti and Nb

The article has intended to give a summary of the investigations of carbides in the new nonledeburitic high-speed steel (NHSS). The carbide phase and its changes during heat treatment have proved to be both qualitatively and quantitatively different from that in conventional HSS. The influence on cutting performance from the dispersed phase has been established. These factors of service properties can be effectively controlled by means of the heat treatment.

Economical non-ledeburitic tool alloys—alloying philosophy, structure and properties

Abstract Economical non-ledeburitic tool alloys are materials of significantly lower carbide particles segregation than in conventional HSSs. Owing to worked out carbon and carbide formers balance, classical eutectic carbides were replaced by primary, hard MC type carbide particles of uniform arrangement. Numerous variants of wrought and cast alloys were produced; tools made of these materials exhibited high service properties.

Tribological characterization of diamond-like carbon films on nonledeburitic high-speed steels

Abstract Hydrogenated diamond-like carbon (DLC) films were deposited on as-tempered nonledeburitic high-speed steel (NHSS) substrates (0–5–1–3Ti–2Nb grade) by capacitively coupled RF glow discharge in a methane atmosphere. The substrates were cleaned with an argon flux before coating deposition. Coatings of 1-μm thickness, good smoothness and adhesion were successfully produced. Microscale abrasive wear tests and field emission scanning electron microscopy were employed to evaluate wear resistance and morphology of the DLC films, substrate–film boundaries and worn components. The wear coefficient of the steel substrates was less than that of M2 tool steel, whereas that for the DLC layer corresponded to the value previously reported for titanium aluminium nitride. Certain decohesion micromechanisms in the NHSS samples after microscale abrasion testing were similar to these found in fractured specimens. Structural influences on the results are discussed.

Application of Micro Wear Testing in Investigations of Super Coarse WC-Co Type Sintered Carbides

The mico-wear abrasion test has recently become a popular method for the measurements of wear resistance of both coated and solid materials. It provides insight into abrasion micromechanisms and quantitative information (wear coefficient) of the tested samples. The investigated super coarse WC-Co composite (WC particles average size of 6-10 μm) reveals the biggest fracture resistance within the whole size range of sintered carbides, at the certain expense of hardness. Super coarse grades are used, among other, as coal mining tools and rock cutting/driling bits. In this work, ball-cratering wear tests were performed using 1 μm diamond particles as the abrasion medium; the abrasives used produced well-defined craters. The worn areas were observed and measured using optical and electronic microscopy, the wear coefficient was calculated based on the increasing sliding distance method. It was found that super coarse sinters abraded with 1 μm diamond grains were more wear resistant than the more fine grained counterparts. This result is attributed to the influence of the large size ratio of WC particles and diamond grains and consequent stronger WC embeding in the metal matrix.

Investigations of the carbide phase and the matrix of non-ledeburitic high-speed steel with Ti and Nb by atomic absorption spectrometry and energy dispersive X-ray spectroscopy methods

This paper presents a computing procedure for the indirect assessment of the matrix composition by AAS of two-stage prepared carbide isolates. Partitioning of carbon and metallic elements between matrix and carbides has been determined. Austenitizing has caused considerable increase in Mo and Cr contents in the matrix related to dissolution of carbides of the M6C type. Tempering resulted in a decrease in contents of elements forming M23C6 secondary carbides. Changes to the Ti and Nb contents in the matrices were relatively small in specimens given various heat treatments. The matrix of annealed steel has been shown to be carbonfree, whereas the carbon content in the tempered state is high in comparison to conventional high-speed steels.

Dissolution of Carbide Isolates in Acids Using Microwave Technique

The paper presents results of the investigation of SM5Ti3Nb2 steel carbide isolates. The acids and acid mixtures for dissolution of selected carbides phase isolates, using microwave technique were specified. This way of dissolution of carbide isolates reduced the time of mineralization to about 10-15 minutes. Presented methods of dissolution can be applied in the chemical analysis of carbide isolates, using atomic absorption spectrometry and optical emission spectrometry inductively coupled plasma. It is indicated the acids, using to removal of noncarbide metallic residue in isolates.

Stereological and Statistical Evaluation of Grain Size in Experimental Ni-Based and Conventional Supercoarse Sintered Carbides

Chemical composition and technology of experimental Ni based binder-tungsten carbide particles composite have been worked out to increase corrosion resistance of conventional supercoarse WC-Co type sintered carbides. All the sintered WC cermets, both with Co and Ni-based binding phase have been manufactured using identical supercoarse WC powder. Grain size evaluation was performed using light microscope images and grain chord length measurements, samples of commercial WC-Co coarse and supercoarse grades being included into analysis for comparison purposes. The obtained statistical and geometrical distributions of the chord length revealed certain differences. The performed statistical analysis allowed to state that the investigated experimental grades of Ni-based sintered WC carbides are materials of microstructure significantly more coarse than the reference coarse commercial grade (i.e. they can be classified into supercoarse group of sintered carbides).