高炭素クロム軸受鋼の焼割れに関する研究 : 第5報、焼割れに及ぼすEthylene Glycol-水系焼入れ液の特性

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Various quench cracks of steel are considered in general to occur under the united thermal and transformational stresses. This paper deals with the effects of characteristics of ethylene glycol (EG)-water quenchant on quench cracks (fin and/or vertical). Cooling rates of silver and steel bars in EG solution (up to 80 vol%) become lower as the concentration of EG increases, while at over 80 vol%, the rates bring the reverse change. This behavior of cooling rates is due to the unique specificity of boiling points in the EG water system. The fin crack by EG solutions ranging in concentration to 80vol% occurred in all specimens at the austenitizing temperatures higher than 780'C. A quenchant containing more than 90 vol% EG results in the decrease of a fin crack and an increase of the vertical crack. Residual tensile stress existed on the surface of the test piece and increased with austenitizing temperature.
1989-05-25