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3.9%C 회주철의 진동감쇠능 및 기계적 성질에 미치는 합금원소 첨가의 영향
김정철,손용철,한동운,백승한 ( J . C . Kim,Y . C . Son,D . W . Han,S . H . Baik ) 한국열처리공학회 1997 熱處理工學會誌 Vol.10 No.1
Flake graphite cast irons with the high damping capacity have been used for the control of vibration and noise occuring in the members of various mechanical structures under vibrating conditions. However, the damping capacity which is morphological characteristics of graphite is one of the important factors in reducing the vibration and noise, but hardly any work has deal with this problem. Therefore, the authors have examined the damping capacity of various cast irons with alloying elements and studied the influences of the matrix, mechanical properties and morphological characteristics of graphite. The main results obtained are as follows: Effects of Ni on the damping capacities and mechanical properties are investigated in 3.9%C-0.3% Cu gray cast iron. At 0.2% Ni content, specific damping capacity showed the maximum value, and decreased with further increase in Ni content, Graphite continuity also showed same behavior. This indicates that the specific damping capacity has a close relation with graphite continuity. On the other hand, the damping capacity in pearlite matrix showed superior to that in ferrite. In contrast, with increasing the Ni content, both tensile strength and hardness increased due to the decrease of graphite length and eutectic cell size.
회주철의 진동감쇠능과 기계적 성질에 미치는 오스템퍼링처리의 영향
백승한,김정철,손용철,한동운 한국열처리공학회 1999 熱處理工學會誌 Vol.12 No.2
Gray cast iron with a high damping capacity has been used for controlling the vibration and noise in various mechanical structures. Nevertheless, its usage has been often restricted due to its poor tensile strength. Therefore, it is necessary to improve tensile strength at the expense of a loss in damping capacity. This study is aimed at finding the best combination of tensile strength and damping capacity by varying austempering time and temperature range from 320℃ to 380℃ after austenization at 900℃ for 1hr. The effect of austempering condition on hardness and the volume fraction of retained austenite is investigated as well. The results obtained are summarized as follows : (1) With an increase in austempering temperature, both tensile strength and hardness decrease while damping capacity improves. (2) Austempering at 350℃, resulting in a mixture of upper and lower bainite with partially retained austenite, exhibits the optimum combination of tensile strength and damping capacity.