Prediction of hardness of aluminum alloy 7055 by quench factor analysis

The Vickers hardness time-temperature-properties (TTP) curve of aluminum alloy 7055 was evaluated by interrupted quench technique. The critical temperature range of TTP curve was determined from 210 degrees C to 420 degrees C with the nose temperature of 355 degrees C. The hardness decreased rapidly with isothermal duration in the critical temperature range. The hardness of aluminum alloy 7055 was predicted by quench factor analysis using the TTP curve and cooling curves. The predicted hardness agreed reasonably well with the measured results. The influence of time step and summation temperature range on the predicted results was studied. The cooling rate through the critical temperature range had dominant influence on the final hardness of the alloy.