Hot Hardness and Hot Corrosion Resistance of High Temperature Alloys

Design, selection, and application of high-temperature alloys for engineering structure, equipment, and component are commonly based upon materials strengths such compression, tensile strength, stress-rupture strength, creep strength, and fatigue strength. Standard materials test methods of these materials properties at elevated temperature have been long established. Safety factors are applied during engineering design according to intended service condition and environment. The mechanical properties are obtained using samples in standard geometry with an assumption of uniform composition and microstructural distribution. Hence, premature failure of high-temperature alloys is often linked to localized variation in composition and/or microstructure.

Accelerated wear rate and localized hot corrosion are two of the common premature failure mechanisms for high-temperature alloys under harsh service environment. Recently developed HBJ(60kg) hot hardness test method/procedure and a procedure of hot corrosion test have been adopted in this investigation for characterizing capability to resist premature failure of high-temperature alloys. A correlation between hot hardness and wear behavior of actual engine valvetrain component has been made. An illustration of hot-corrosion test results in correlation to actual engine hot corrosion appearance has been given.