Issue << content << Estimation of Steel 08X18H9 Degradation by Kinetics of Coercive Force


DOI: 10.12737/15953

2015. Vol.18. No. 4, pp. 14-16

Estimation of Steel 08X18H9 Degradation by Kinetics of Coercive Force

V. A. Nekhotiashchiy, A. L. Palienko, О. P. Gopkalo

Introduction. In welded structures made of austenitic steels development of magnetic properties in the materials is related with the formation of ferromagnetic phases of ferrite and martensite under the action of elastoplastic strains (during metal forming) and high temperatures (during welding and thermal treatment). Presence of ferromagnetic phases of ferrite and martensite has a significant influence on the corrosion stability, fracture toughness, crack susceptibility and etc., which results in the degradation of metal in welded structures.
Method. The developed method involves the experimentally determined connection between stresses-strains and values of coercive force as well as volume of α-phase in metal, changing of which represents the degradation of metal and its service properties.
Results. It was experimentally determined that at elastoplastic deformation the increase in the values of coercive force Нс is related with the formation of the volume of α-phase in the austenitic steel. The correlation between stresses-strains and values of coercive force as well as volume of α-phase in metal was determined, and their boundary values, which correspond to the limiting state of the material that is its fracture, were found.
Discussion. The established connection between stresses-strains of metal, volume of ferromagnetic phase and coercive force makes it possible to perform an expert assessment of the stress-strain state and degradation of metal in the most loaded regions of the structural elements made of austenitic steels. To reduce the critical level in the degradation of service properties of austenitic steel it is required to keep control over its magnetic properties and content of ferromagnetic phase in metal using coercimeter and ferrite meter.
 
Keywords: stresses, strain, a-phase, coercive force, degradation
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