The control of cooling power is very important to introduce desired properties. Usually, higher the cooling rate higher the quench hardness and distortion and the optimization of cooling power is the base for good hea...The control of cooling power is very important to introduce desired properties. Usually, higher the cooling rate higher the quench hardness and distortion and the optimization of cooling power is the base for good heat treatment. The change of cooling speed during quenching is one of the effective methods to balance hardness and distortion. Different form the general knowledge of the demerit of vapor blanket stage, oil with long vapor blanket stage is also one of effective methods to reduce distortion. The reduction of distortion with enough quench hardness seems to be possible by optimization of cooling condition by the help of computer simulation. The exhibition of higher core hardness than surface in through hardening steels experienced in the "Inverse quench hardening" was introduced by Prof. Tamura and Shimizu. This mechanism is well explained by Arimoto et al, by analysis of computer simulation. In this paper, plural steps cooling methods are compared, in relation with cooling curve and heat transfer coefficient that is necessary to simulate quench results and the possibility of advanced cooling technology is discussed.展开更多
The appearance of lower hardness at the surface than at the core after through-hardening of steels is known as "inverse quench-hardening." Pioneering work was performed in the 1970s by establishing a simple ...The appearance of lower hardness at the surface than at the core after through-hardening of steels is known as "inverse quench-hardening." Pioneering work was performed in the 1970s by establishing a simple test procedure where cylindrical specimens were cooled by air and brine sequentially to produce the effect. This phenomenon was described in relation to the polymer quenching and its effect to the improvement in the fatigue strength of the steel in the 1990s. The hardening mechanism in the same specimens as the pioneering work was recently examined using a finite element simulation method. However, this work has not been completed for lack of experimental quenching cooling curves for the comparisons. In this study, the same experiments using 20mm diameter cylindrical specimens as those of the pioneering work were conducted to obtain cooling curves and hardness distributions for comparing simulated results. Experimental cooling curves showed a temperature recovery as predicted by the simulation. Also the inverse quench-hardening phenomena were found in the measured and simulated hardness distributions of the specimens.展开更多
文摘The control of cooling power is very important to introduce desired properties. Usually, higher the cooling rate higher the quench hardness and distortion and the optimization of cooling power is the base for good heat treatment. The change of cooling speed during quenching is one of the effective methods to balance hardness and distortion. Different form the general knowledge of the demerit of vapor blanket stage, oil with long vapor blanket stage is also one of effective methods to reduce distortion. The reduction of distortion with enough quench hardness seems to be possible by optimization of cooling condition by the help of computer simulation. The exhibition of higher core hardness than surface in through hardening steels experienced in the "Inverse quench hardening" was introduced by Prof. Tamura and Shimizu. This mechanism is well explained by Arimoto et al, by analysis of computer simulation. In this paper, plural steps cooling methods are compared, in relation with cooling curve and heat transfer coefficient that is necessary to simulate quench results and the possibility of advanced cooling technology is discussed.
文摘The appearance of lower hardness at the surface than at the core after through-hardening of steels is known as "inverse quench-hardening." Pioneering work was performed in the 1970s by establishing a simple test procedure where cylindrical specimens were cooled by air and brine sequentially to produce the effect. This phenomenon was described in relation to the polymer quenching and its effect to the improvement in the fatigue strength of the steel in the 1990s. The hardening mechanism in the same specimens as the pioneering work was recently examined using a finite element simulation method. However, this work has not been completed for lack of experimental quenching cooling curves for the comparisons. In this study, the same experiments using 20mm diameter cylindrical specimens as those of the pioneering work were conducted to obtain cooling curves and hardness distributions for comparing simulated results. Experimental cooling curves showed a temperature recovery as predicted by the simulation. Also the inverse quench-hardening phenomena were found in the measured and simulated hardness distributions of the specimens.
