AC8A 알루미늄합금 주조재의 열처리에 의한 특성 평가

Abstract

Aluminum is a active metal and it is well known that its oxide film exhibits a thin and protective barrier which is comparatively stable in both air and neutral aqueous solution. Thus, Aluminum alloys have been widely applied in architectural trim, cold & hot-water storage vessels and piping etc., furthermore, the aluminum alloy of AC8A have been widely used in mold casting material of engine piston because of its properties of temperature and wear resistance. In recent years, the oil price is getting higher and higher, thus the using of oil of low quality have been significantly increased at engines of ship and vehicle. Therefore it is considered that evaluation of corrosion resistance as well as wear resistance of AC8A material is also important to improve its property and prolong its lifetime. In this study, the effect of solution and tempering heat treatment to corrosion and wear resistance is investigated with electrochemical method and measurement of hardness. The hardness decreased with solution heat treatment compared to mold casting condition, however, its value increased with tempering heat treatment and exhibited the highest value of hardness with tempering heat treatment(temperature at 190OC for 8 hrs). Furthermore, corrosion resistance was increased and decreased with decreasing and increasing of hardness respectively. As a result, it is suggested that the optimum heat treatment to improve both corrosion and wear resistance is tempering heat treatment(temperature at 190OC for 2 hrs).