29.06.2009 Pressing & Sintering

A Low-Cost Option for Manufacturing PM Stainless Steel Exhaust Flanges and Hego Bosses

Traditionally, PM exhaust flanges and HEGO bosses are manufactured from 409L stainless steel powder by employing high temperature, hydrogen sintering. High temperature, hydrogen sintering is deemed essential for meeting the minimum specified sintered density of 7.20 g/cm3 set forth by OEMs. Compacting pressures employed typically range from 620 to 760 MPa (45 to 55 TSI), and the sintering temperatures range from 1288°C to 1388 °C (2350 °F to 2530 °F). A newly developed low chromium ferritic stainless steel, designated 410LV (patented), exhibits greater sinterability compared to the standard 409L. By selecting this alloy it is feasible to achieve a sintered density of 6.90 g/cm3 under mesh-belt sintering conditions (below 1177 °C, 2150 °F). This represents a significant reduction in the cost of manufacture. Low temperature sintered 410LV offers mechanical strength, corrosion resistance, and weldability that may satisfy the requirements of some of the exhaust flange and HEGO boss applications. This paper covers the properties of low temperature sintered 410LV, and compares those with the properties of similarly processed 409L.