Improvement of Copper Alloy Springs. III : Secular Change in Spring Materials of Brass Series
AbstractOne of the most unfavorable defects of a spring sheet of brass is that the spring properties change with time even at room temperature after final cold-working or low-temperature annealing. An investigation was made into the possibility to suppress the so-called secular change after low-temperature annealing. The change after low-temperature annealing was considered to be related to that after final cold-rolling. The secular change after cold-rolling showed a tendency to stabilize the spring properties and, when a rolled brass plate was annealed at low-temperature after it was allowed to remain at room temperature for a time long enough for stabilization, the change after low-temperature annealing became less. The secular change in two-phase brass, namely, 60/40 brass could be considered as a combined effect of α- and β-brass, though β-brass showed more complicated change than α-brass. All the experiments were carried out at room temperature and at the constant temperatures of 25°and 40℃.