Low Temperature Creep Behavior of PM Components Under Static Load Conditions

Paper i proceeding, 2013

Increasing demand on PM steels for automotive applications necessitates high performance structural components with good tolerances and mechanical properties. However, it has been found that some sinter parts lack dimensional stability due to unexpected creep or relaxation under high and prolonged static loading conditions. The present investigation deals with the low temperature creep behavior of sintered steel grade Distaloy HP under high static loading conditions. Experiments were therefore performed on sinter-hardened and subsequently tempered standard tensile specimens, involving the comparison of effect of tempering at 200 and 300°C. When having constant load of 20 kN, equivalent to stress level of almost 90% of the yield stress, tempering as such and higher tempering temperature in particular lowered the creep response or relaxation when testing at slightly elevated temperatures of minimum 90-100C. Hence, proper tempering can reduce the dimensional instability otherwise experienced for the studied PM steel at high static loads applied for long periods of time.