DEGRADATION OF 0.5Cr-0.5Mo-0.25V STEEL MICROSTRUCTURE DURING EXPLOITATION
Journal Title: Materials Engineering - Materialove inzinierstvo (MEMI) - Year 2011, Vol 18, Issue 2
Abstract
Degradation of 0.5Mo-0.5Cr-0.25V material after long-term high-temperature service has been studied by means of microstructure and mechanical properties analysis. Samples were taken from the pipeline with steam leaking found after almost 200,000 h service at 565 °C. The microstructure and properties have been compared with similar materials at similar exposure conditions without any signs of the rupture. Highly tempered ferrite contains secondary particles of MC, M2C and a kind of Cr-rich carbide (M23C6 and/or M7C3) in all materials studied. The difference have been found in the values of hardness. Fractures of samples after the impact test at various temperatures with typical embrittled features are also described. Analysis of the material service history like warm and cold starts-up, conditions of thermal and mechanical fatigue, together with microstruc¬ture and mechanical properties lead to the conclusion that the material was overtempered. The exhaustion of material deformationability resulted in the rupture-leakage of a component in the place of highest stresses.
Authors and Affiliations
Anna Výrostková, Ján Kepič, Roman Macko, Viera Homolová
Investigation of possible causes for appearance of a crack in the welded joint of the ship winch frame
Ship winches are one of the most important parts of the ship equipment since they perform the most responsible tasks on various ships. In the majority of cases, the ship winches are welded structures. All the necessary c...
THE ROLE OF OBJECTIVE FUNCTION IN ENGINEERING DESING
The process of material choice is a key element in the production of machines, devices and other engineering constructions. Engineering design relates to the design of engineered artifacts formed by materials of various...
INFLUENCE OF GRAIN SIZE ON DUCTILITY OF MAGNESIUM ALLOYS
The paper give a brief overview on the effect of grain size on the yield strength and the elongation to fracture (ductility) of magnesium alloys. The yield stress, flow stress and fracture stress decrese with decreasing...
FATIGUE BEHAVIOR OF HOT-ROLLED STEEL INTENDED FOR COLD FORMING
In the work, there are presented measured tension and fatigue properties of eight low-carbon steels moulded in form of 20 kg ingots that were processed by controlled regime of rolling /cooling and then exposed to simulat...
Fatigue Crack Propagation Under Variable Amplitude Loading Analyses Based on Plastic Energy Approach
Plasticity effects at the crack tip had been recognized as “motor” of crack propagation, the growth of cracks is related to the existence of a crack tip plastic zone, whose formation and intensification is accompan...