Saša Kovačić

Influence of Steel Substrate on the Properties of PACVD Gradient Multilayer TiCN Coating

Titanium-based hard coatings are known for increasing both hot work and cold work tool steel performance in terms of wear and corrosion resistance. In this paper, the influence of different steel substrates on the properties of plasma-assisted chemical vapor deposition (PACVD) gradient multilayer titanium carbo-nitride (TiCN) coating was investigated. The same gradient multilayer TiCN coating was deposited by pulsed direct current (dc) PACVD on a hot work tool steel grade X37CrMoV5-1 and two Bohler cold work tool steels K390 PM and K110. Hardened samples of each steel were also included in the investigation. The coating-substrate systems have been characterized with respect to their chemical composition, thickness, adhesion, and resistance to electrochemical corrosion, abrasion, erosion, and dry sliding wear. The results show an increased wear and corrosion resistance of TiCN-coated specimens compared with noncoated and prehardened specimens. The application of gradient multilayer TiCN coating on different steel substrates shows the different behavior of TiCN coating. Therefore, besides the coating itself, the base material on which the coating is applied has a significant influence on the tool properties.

Effect of deep cryogenic treatment on dilatometric curve and tribological properties of high speed steel

Advantages of deep cryogenic treatment (DCT) over the standard heat treatment of high speed steels for the purpose of obtaining better properties are quoted in an increasing number of scientific papers to be found in literature. This paper deals with the improvements in high speed steel properties achieved by using DCT on test samples made of PM S390 MC high speed steel. The effect of DCT on the dilatometric curve during tempering and on the abrasive and the erosion wear resistance has been investigated and compared with results obtained from a set of test samples made of the same steel heat treated by the conventional method (hardened and three times high temperature tempered). Dilatometric tests confirmed the existence of common processes in tempering, which depend on the initial state of steel (only quenched, and quenched and deep cryogenically treated). These tests showed that the DCT had not completely eliminated the residual austenite, particularly in the case of the highest austenisation temperatur...

Effect of the heating rate in the tempering of DIN 100 V1

Abstract In this paper, the effect of the heating rate on the process of tempering and the obtained hardness of the DIN 100 V1 (AISI W2) carbon tool steel has been investigated and determined. Steel specimens in two initial states were investigated: after quenching and after quenching and deep-cryogenic cooling. The specimens were submitted to tempering in a dilatometer, varying the heating rates, temperature of tempering between 200°C and 690°C and duration of keeping the specimens at that temperature. A common effect of these factors on the temperature of the start of particular stages in tempering and the obtained properties was determined using dilatometry. Differential dilatation analysis was carried out, together with hardness tests and XRD (X-ray diffraction) analysis.