Applications and Design of Low Temperature Surface Hardened Stainless Steel Components in Automotive Applications 2016-01-0425

While the excellent corrosion resistance of austenitic and duplex stainless steels has resulted in wide commercial application, poor tribological behavior, especially low abrasive/adhesive wear resistance and a tendency to fret, has prevented the use of these materials in applications where both corrosion and wear resistance are required. For more than 20 years low temperature carburizing or nitrocarburizing has offered a solution to enhance mechanical properties without altering the corrosion resistance. These thermo-chemical diffusion processes form carbon or nitrogen S-phase while avoiding carbide precipitation that causes sensitization. This paper presents application and design examples of low temperature carburized austenitic stainless steels in kinematic and static parts of automobiles. For example, kinematic components attached to the engine have to resist a relatively high corrosive loading in combination with temperatures exceeding 500°C. Furthermore these kinematics suffer from fretting fatigue on the bearing due to the vibration of an engine during its years of service. The galling, fretting, wear, and corrosion resistance of stainless steels equipped with Carbon S-Phase can withstand these forces. Especially in the automotive industry, a very reliable and reproducible solution is required and low temperature carburizing or nitrocarburizing fits the demand for cost efficient, durable, and corrosion resistant high volume components.