Influence of silver on structure and properties of low-carbon steel

Abstract

Silver has only slight solubility in low–carbon steel at elevated temperatures (~ 0·08 wt-% at the solidus) and precipitates on cooling as fine particles (< 10 nm) in the interphase mode. When present in as-cast steel at an estimated volume fraction of ~ 0·0006, silver can cause precipitation strengthening of up to 50 MN m−2. In as–rolled and in normalized steels, silver (0·02 wt-%) improves both strength and toughness mainly through grain refinement, with only a small influence from precipitation hardening. An important observation is the improvement to the heat affected zone toughness of high heat input welds which can result from small silver additions (0·02 wt-%) to C–Mn–AI–V steels. However, because of its relatively high cost, it remains to be demonstrated whether silver will impart sufficient benefit to steel properties to be commercially acceptable as an alloying addition.MST/44