ANALYSIS OF THE DAMAGE OF FUNCTIONAL BASED ON THE COBALT-RESISTANT ABRASION LAYERS

1 KRAUS Martin
Co-authors:
1 BYSTRIANSKÝ Jaroslav
Institution:
1 VSB-Technical University of Ostrava, RMTVC, Ostrava, Czech Republic, EU, martin.kraus@vsb.cz
Conference:
24th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, June 3rd - 5th 2015
Proceedings:
Proceedings 24th International Conference on Metallurgy and Materials
Pages:
1540-1546
ISBN:
978-80-87294-58-1
ISSN:
2694-9296
Published:
12th January 2015
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
313 views / 120 downloads
Abstract

Cobalt-based alloys (e.g. Stellite) are often used on surfaces which are required for the high resistance to abrasion (sealing surfaces of the fittings, etc.). These surface layers are commonly applied to low alloyed steel Grade 22 or martensitic steel Grade 91 by welding techniques using. When using armatures with these layers in energetic plants (high pressure valves) have shown operating experience that occurs in damage to functional layers often. The typical damage is characterized by cracking and flaking (release) of the functional layer. This paper deals with the analysis of the causes of such damage to the surface layer of the ball valves (or their contact faces) after the low-cycle service application in superheated steam (550 °C/10 MPa). Layers were applied to the steel AISI 316. For this research were used methods of metallography, chemical and SEM analysis, phase and XRDA microanalysis, hardness and microhardness testing. It was found selective cracking in the areas of a specific phase composition. The subsequently release of material particles and other damage to the surface by these particles.

Keywords: Cobalt-based alloys, welding layers, damage, ball valve, microhardness

© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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