AGE HARDENING OF A PB-0.1WT-PERCENT-CA-0.3WT-PERCENT-SN ALLOY AND THE EFFECTS OF HEAT DURING BATTERY MANUFACTURING ON THIS PROCESS

Age hardening, and the effects of heat exposure on this process, are studied for a cast Pb-0.1wt.%Ca-0.3wt.%Sn alloy. Although the alloy is age hardenable, samples quenched immediately after solidification harden and start overageing very quickly. By contrast, air-cooled samples harden slowly over a considerably longer period and reach a higher peak hardness. The high rate of hardening of quenched samples compared with air-cooled samples may result from a decrease in the degree of the slow grain boundary movement and an increase in the rate of precipitation. Exposure to heat does not decrease the hardness and the grain morphologies remain unchanged. Hardness is increased significantly by exposure to heat, particularly at 70-degrees-C for a long time and also at 200-degrees-C for a short time.