Effect of Isothermal Ageing on Microstructure and Mechanical Behavior of 0.5Cr-0.5Mo-0.2V Low Alloy Steel

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  • Ranjana Kumari
  • Goutam Das CSIR-National Metallurgical Laboratory, Jamshedpur, Jharkhand, India

Klíčová slova:

Spheroidisation, carbides, secondary precipitation, ageing

Abstrakt

Cr-Mo-V based low alloy steels are widely used in thermal power plants because of theirability to withstand elevated temperature and high pressure under continuous operation. Withferrite-pearlite and/or ferrite-bainite microstructures, these steels find their applications inboiler tubes, pressure vessels and steam turbines. Being cost effective is one of the importantfactors, which draws attention of many industrialists towards low alloyed steels over highlyalloyed steels with austenitic matrix. In this work, the microstructure and mechanicalproperties degradation of low alloy steel sample were analyzed. Investigated material was inservice for 35 years. During its service life, it was exposed to high temperature and pressureresulting in properties to undergo changes. To figure out these evident changes, sample wassolutionized and tempered for different ageing times under laboratory conditions. Changes inthe morphology of the steel microstructure such as pearlite decomposition, carbideprecipitation and spheroidisation etc. could be observed. Due to its coherent relation withmicrostructure, mechanical properties were also found to have undergone variations. In orderto investigate the behavior of this steel after its exposition to different environments, hardnessand tensile tests were conducted. Microstructural evolution of the sample was observed usingSEM. TEM analysis was done to figure out the nature of carbides formed duringexperimentation. Experiments revealed the improvement in mechanical properties of the steelin the initial hours of its service due to the phenomenon of secondary precipitation. But, afterreaching its peak condition (over-ageing) deterioration in the properties started.Cite this ArticleRanjana Kumari, Goutam Das. Effect ofIsothermal Ageing on Microstructure andMechanical Behavior of 0.5Cr-0.5Mo-0.2V Low Alloy Steel. Journal ofMaterials & Metallurgical Engineering. 2015. 5(3): 7–14p.

Stažení

Publikováno

2015-11-16

Číslo

Vol 5 No 3 (2015)

Sekce

Research Articles

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