Studium vlastností návarů s karbidy wolframu

Abstract

Functional components of machines are exposed to unstable loads during their service life. In the initial phase, the process takes place without visible signs, which over time and under the way of loading are subject to various types of wear leading to irreversible lost of material. Therefore, there is an increasing emphasis on the development and research of new, more durable materials and technologies that lead to extended life of these parts. The dissertation solve the issue hardfacing in a protective atmosphere M21. As additive materials were used STEIN - MEGAFIL A 220 M and MEGAFIL A 760 M, which form an austenitic and martensitic matrix. During hardfacing, tungsten carbide particles with a size of about 2 mm were added to this Hardfacing using a vibrating feeder. The entire hardfacing was made on structural steel S 690 QL. The main objectives of the work includes the analysis of metallurgical processes and structural changes in both types of additional materials with respect to the used hardfacinging parameters. The hardfacings were subsequently tested for resistance to abrasive wear by the Pin-on-disc method, the next step were hardness and micro-hardness of selected sites were evaluated, the chemical analysis of the hardfacing by electron microscopy and comparing the amount of tungsten carbide particles with the final surface life. The result of the dissertation is an assessment of the properties of hardfacings with inserted grains of tungsten carbide with respect to the use of different matrices of hardfacings in order to prolong the life and safety of hardfacings when used in practice.