Covering Alloy To Lead Bath In High Temperature

Lead bath heat treating is widely used as one conventional heat treatment method in wire-steel products. Now, the application and generalization have been restricted for no appropriate lead covering. Two kinds of different component Al-Cu and Al-Si series alloy are selected as the vehicle to investigate the leak tightness performance as the lead covering alloy, these two kinds of alloy are firstly investigated in the lead covering industry.In this paper, alloy liquidity is measured by means of gravity-assist pouring, alloy oxidation resistance, microstructure, fractograph and oxidized interface in the high temperature are observed and analyzed by means of SEM and XRD. A self-designed setup is used to collect the gas sample under the simulated environment which the covering alloy works in, then the gas sample is detected and analyzed by means of flame atomic absorption spectrophotometer to test the alloy leak tightness, and the best performance covering alloy can be found for lead bath. The results show that: Cu-36%Al-X alloy have the better liquidity performance than Cu-30%Al-X alloy in the pouring temperature of 950℃, Al-20%Si-X alloy have the better liquidity performance than Al-30%Si-X alloy in the pouring temperature of 900℃. The Al-20%Si-X alloy has the best liquidity performance according to the relation factor.The oxidation resistance performance of Cu-30%Al-X alloy is better than Cu-36%Al-X alloy's in work temperature. The oxidation resistance performance of Al-20%Si-X alloy is better than Al-30%Si-X alloy's. Compared the added weight of alloy, the number of Cu-Al alloy is smaller than Al-Si alloy's. Research showed that there are pellumina in the surface of Cu-Al alloy, pellumina and silicon oxide, the kainotype of pellumina and silicon oxide in surface of Al-Si alloy.The concentration of lead steam is 284mg/m3 when detecting above the lead bath without any covering alloy, When using Cu-36%Al-X alloy as the lead bath covering alloy, the detected concentration of lead steam through the covering alloy is 31.9mg/m3 which is 88.2% decreased than the uncovered concentration, When using Al-20%Si-X alloy as the lead bath covering alloy, the detected concentration of lead steam through the covering alloy is 6.47mg/m3 which is 97.73% decreased than the uncovered concentration, so the Al-20%Si-X alloy'leak tightness performance is significant.