Analysis of Tribological Properties of Powdered Tool Steels M390 and M398 in Contact with Al2O3

Abstract

The present article examines special steels used for the production of injection screws in the plastic industry, with a glass fiber content of up to 30%. Experimental materials, M390 and M398, are classified as tool steels, which are produced by powder metallurgy-HIP methods (hot isostatic pressing). The main goal of the presented paper is to propose the optimal tempered temperature of M398 steel and also to compare the tribological properties of both materials and to determine the degree of their wear depending on their final heat treatment. Partial results refer to the analysis of hardness, roughness, the overall wear mechanism, the change in the volume of retained austenite due to the tempering temperature, and the EDS analysis of the worn surfaces in individual contact pairs. A ceramic ball Al2O3 in the α phase was used as the contact material, which had a diameter of 6.35 mm. The ceramic ball performed a rotational movement on the experimental material surface at an elevated temperature of 200 °C using the dry ball-on-disk method. It was experimentally shown that the new M398 material can fully replace the M390 material because it exhibits significantly better tribological properties. The M398 material showed more than a 400% reduction in wear compared to the M390 material. The ideal heat treatment consisted of cryogenic quenching to −78 °C and a tempering temperature of 400 °C. At tempering temperatures of 200 and 400 °C, adhesive wear occurred, which was combined with abrasive wear at a tempered temperature of 600 °C. The averaged coefficient of friction (COF) results show that the M398 material presents less resistance in the friction process and its values are approximately 0.25, while the M390 material showed a COF value of 0.3 after the cryogenic hardening process. The friction surface roughness of the M398 materials also showed lower values compared to the M390 material by approximately 35%. Both of these results are related to the content of M7C3 and MC carbide particles based on Cr and V in the bulk of the material, which are in favor of the M398 material.

The Influence of the Geometry of Movement during the Friction Process on the Change in the Tribological Properties of 30CrNiMo8 Steel in Contact with a G40 Steel Ball

“…After releasing this material, which takes place in two parts, the first part of the material moves to the edge parts of the friction track, and the second part of the material, which is in a smaller proportion, is pushed into the surface of the friction track by a pressure ball and acts as an abrasive particle. The alternation of these methods of accumulation and the release of microparticles caused the fluctuation of the curve in question [ 30 ]. The appropriate COF value for the ball on disc method was 0.59.…”

“…The main experiment was performed on the tribological device UMT TriboLab (Bruker Corporation, Billerica, MA, USA) from Bruker [ 29 , 30 ]. This device offers the possibility of the modular exchange of different parts of the device, which allows for the use of different kinds of tribological process methods.…”

Study of the Influence of the Copper Component’s Shape on the Properties of the Friction Material Used in Brakes—Part One, Tribological Properties

“…This method is successfully used in various fields of science [ 27 , 28 , 29 , 30 , 31 ]. Tests using ball contact are also performed, for example, in chambers with regulated conditions, e.g., temperature [ 32 ]. Counter-samples of various shapes are also used, e.g., a cylinder cooperating with a sphere with its side [ 33 ] or front surface [ 34 ].…”

Microstructural Changes and Determination of a Continuous Cooling Transformation (CCT) Diagram Using Dilatometric Analysis of M398 High-Alloy Tool Steel Produced by Microclean Powder Metallurgy

“…The composition of the etchant consisted of 10 mL HNO3, 10 mL H2O2, 20 mL HCl, and 20 mL glycerin [47]. Thanks to the increased occurrence of carbide particles in the M398 steel, we can state that it would be possible to create screws enabling the processing of plastics with increased content of glass fibers [48]. The chemical composition of the experimental sample was determined and compared with the data from the steel manufacturer using spectral analysis on a SPECTRO-MAXx LMX10 device.…”