高炭素クロム軸受鋼の焼割れに関する研究 : 第3報,焼割れに及ぼすポリマ焼入れ液の曇点の影響

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The preceding paper has shown that the increase of polyalkylene glycol (PAG) polymer concentration results in a decrease of fin cracks and an increase of vertical cracks, because of the clouding point (81℃) of PAG sol.. This paper deals with the effects of the clouding points of quenchant on the quench cracking of a SUJ 2 bar. The clouding point is affected enormously over pH 13.0 of the PAG quenchant and goes down to 43℃ at pH 13.5. The high cooling rate of the PAG quenchant is obtained by the low clouding point quenchant. Therefore, the behavior of quench cracking in the pH 13.5 PAG sol. is similar to that of water. When SUJ 2 was quenched from austenitizing temperature 800℃, a considerable tensile stress existed on the surface area of all specimens, regardless of their pH values. A gel permiation chromatogram shows that the thermostability of PAG quenchant is excellent under sever conditions.
1987-12-25