Tool Steel Surface Research Articles

Tempering behaviour of hardened surface of T1 high speed tool steel after laser heating

We show that the tempering stability of the surface of T1 high speed tool steel can be greatly improved when laser heating is used for the hardening process. The surface resistance to temper softening can be raised by 150 to 200°C. The tempered hardness is still as high as HRC 58 (i.e. Rockwell hardness), even when tempered at 700°C. The hardness of the laser-hardened zone is greater by 6–7 HRC numbers, when compared with the conventional heating and quenching technique.

Interface study of physically vapour-deposited TiN coatings on plasma-nitrided tool steel surfaces with Auger electron spectroscopy, resonant nuclear reaction analysis and Rutherford backscattering spectroscopy

Interface study of physically vapour-deposited TiN coatings on plasma-nitrided tool steel surfaces with Auger electron spectroscopy, resonant nuclear reaction analysis and Rutherford backscattering spectroscopy

Interface study of physically vapour-deposited TiN coatings on plasma-nitrided tool steel surfaces with Auger electron spectroscopy, resonant nuclear reaction analysis and Rutherford backscattering spectroscopy

It is known that adhesion of a TiN coating on a plasma-nitrided tool steel surface depends strongly on the kind of substrate material and on the process steps between plasma nitriding and deposition of TiN. To obtain relevant information concerning the interface composition a combined Auger electron spectroscopy (AES), resonant nuclear reaction analysis (RNRA) and Rutherford backscattering spectroscopy (RBS) analysis has been performed. With these techniques, mutually complementary information could be obtained by measuring quantitative nitrogen (RNRA) and qualitative nitrogen, titanium and iron depth profiles (AES). The composition of the interface between the TiN coating and the plasma-nitrided surface was deduced from both AES and RBS results. The results indicate that the transition treatment carried out between plasma nitriding and TiN coating influences the interface composition. They will be explained in relation to previous adhesion results. The work was carried out on high speed steel ASP 23 and on cold-worked steel 1.2379.

Friction and wear behavior of alumina-based ceramics in dry and lubricated sliding against tool steel

The friction and wear behaviors of five different grades of alumina ceramics sliding against a tool steel surface were studied for both the dry and the water-lubricated conditions. Sliding experiments were performed in a block-on-ring configuration. The tribological behavior was studied with respect to the composition of alumina and the changes in normal load and sliding speed. It was found that in dry sliding the wear resistance of pure alumina was the best and it decreased with the addition of silicate glassy phase and/or zirconia to alumina. There was a linear increase in wear resistance with increasing hardness but no such correlation was found between wear and fracture toughness. In sliding under water-lubricated conditions, the coefficient of friction and wear rates of alumina were considerably reduced. The tribological behavior of alumina in the presence of water was affected by corrosive damage. These factors together with the transfer of material between sliding surfaces were verified by scanning electron microscopy and energy-dispersive X-ray analysis of the worn surfaces.

Characterization of TiN coatings deposited on plasma nitrided tool steel surfaces

Wear-resistant TiN coatings deposited on tool steels are used frequently in industry. There is a trend towards further optimizing these coatings, e.g. by plasma nitriding the tool surface prior to TiN deposition. In this work the influence of the nitriding conditions on the surface properties of AISI 304 and ASP 23 tool steels was investigated. The plasma nitriding was carried out in a triode ion plating configuration normally used to deposit TiN coatings. At the surface of AISI 304 stainless steel, only a thin compound layer (Fe 4N, Fe 3N) was found, probably as a consequence of the rather slow nitrogen diffusion in the austenite matrix. For ASP 23 high speed steel, the different nitriding behaviour of the martensitic matrix causes the formation of a diffusion layer which results in an increasein hardness at the surface. On an analogous set of specimens the TiN deposition was started immediately after the plasma nitriding. To optimize this combined treatment, the influence of the nitrogen content of the nitriding medium and that of the thickness of an intermediate titanium layer were examined. By means of X-ray diffraction only an influence on the lattice parameter of TiN and the nitriding layers was found, as compared with the lattice parameter for the separate treatments. Bad adhesion of TiN coatings on plasma nitrided AISI 304 was observed and was explained in terms of the high internal stresses in the compound layer on the nitrided surface. For the ASP 23 substrate a better coating adhesion was observed, probably due to a different structure of the nitriding layer and to the enhanced substrate harness. At this stage of the research, none of the above-mentioned nitriding treatments results in a sufficient adhesion of the TiN layer, although some useful facts could be established for further research.

The influence of titanium nitride reactive magnetron sputtering on hardened tool steel surfaces

SIS-2140 † † SIS-2140 is a Swedish standard. hardened tool steel was coated with TiN by reactive magnetron sputtering. In this work we have studied the influence of the substrate deposition temperature on the chemical composition at the interface as well as the adhesion and hardness of the TiN film and the substrate. For the chemical composition study, Auger electron spectroscopy, glow discharge optical spectrometry (GDOS) and electron probe microanalysis were used. For the adhesion and hardness measurements, a scratch tester and Vickers micro- and ultramicrohardness testers were used. At a substrate deposition temperature of 400 °C the critical load value is at a maximum. At this temperature the Si:N, Cr:N, C:N, Fe:N, C:Ti and O:Ti(GDOS) relative intensity ratios are also at a maximum. The TiN film shows an adhesive failure mechanism up to 330 °C and a cohesive failure mechanism at higher temperatures. The substrate surface hardness drops from 820 to 470 VHN after TiN deposition at a substrate deposition temperature of 200 °C. The TiN surface and bulk hardness in cross-section increases from 200 to 350 °C and decreases again between 350 and 600 °C.

Effects of Reagents on Electrodischarge Machined Surfaces and Globule Appendages

The effects of a range of acidic and alkaline reagents on the electrodischarge machined (EDM) surface of AISI D6 tool steel have been investigated. The acidic reagents were found to attack mainly the underlying parent metal at the roots of fine fissures in the recast layer, causing severe localised pitting of the EDM surface. The alkaline reagents, however, reacted strongly with the recast layer, giving rise to an evenly pitted surface. The results indicate that the majority of the globule appendages produced by EDM are fused firmly on to the recast layer. They become an integral part of the surface and cannot be easily dislodged by chemical means.

Corrosion damage of the surface of high-speed tool steel in acid-inhibitor pickling

Profilograms were recorded of the surface of 20-mm-diameter 1.5-mm-thick specimens prepared from hardened and tempered R6M5 high-speed tool steel (62 HRC) and also of similar specimens subjected to the action of pure hydrochloric acid etching solution and of the same solutions with additions of KhOSP-10, KhOSP-10D, and urotropin inhibitors at 30, 60, and 90/sup 0/C for 4.0, 2.0, and 0.5 h, respectively. The analysis of corrosion damage and determination of the surface finish of the steel made it possible to develop the optimum method of acid-inhibitor pickling specifying the addition to the acid of 1.5 g/liter KhOSP-10 inhibitor and a temperature of 30/sup 0/C. This suppressed the corrosion rate, hydrogen impregnation and embrittlement, decarburization of the steel, and sensitivity to crack formation, and reduced the number of scrapped parts.

Auger spectrometric studies on fracture surfaces of tool steel

AbstractThe fracture surfaces of tool steel K‐13 (Hungarian Standard) were studied by Auger electron spectroscopy. Notched specimens of 3 × 3 mm2 were fractured in UHV (6 × 10−8 Pa) with a fracturer (Riber FR 100) and studied with a CMA analyser (Riber OPC 103). With our modification the fracturer was operated within the −150°C −+230°C temperature range. The fracture surfaces were tested with a scanning electron microscope (JEOL JSM 35). The evaluation of Auger spectra was based on the PHI (PALMBERG et al.). Handbook, however the backscattering correction of Jablonski was applied in some cases. The choice of adequate fracturing temperature proved to be very important. Low temperature fracture of this steel alloy is producing very rigid transgranular fracture. The effects of sample heat treatment and of fracturing temperature as well were studied in details. The Auger spectra of fracture surfaces are strongly affected by the heat treatment of the samples. The grain boundary fracture surface of a sample austenitized at 1100°C quenched and tempered at 600°C exhibited a strong enrichment of P, correlating with the enrichment of Cr, V and Mo. The transgranular fracture surface of the same sample but without tempering corresponded to the bulk composition. In some cases and spots on the fracture surfaces, giant S or P peaks were associated with secondary phases (inclusions) on the SEM pictures.