軟化之退火退火之程序包括加熱至较高之温度,經相當時間後逐步冷却,使硬度較爲降低,以便於加工。低合金之鑄铁中,爲完成此項退火,可加熱至550℃以上及900℃以下;但須加控制,勿使石墨化部份過廣而减低其强度。[表十一]及[圖十三、十四]表示各種温度對灰鑄铁之硬度、化合炭之份量、及拉力强度之影響。合金灰鑄铁在退火時,困難较 Softening annealing annealing procedures include heating to a higher temperature, after a considerable period of time gradually cooling, so that the hardness is lower, in order to facilitate processing. Low-alloy cast iron, in order to complete the annealing, can be heated to more than 550 ℃ and 900 ℃; but to be controlled, do not make the graphitization part is too wide and reduce its strength. [Table 11] and [Figure 13, 14] indicate the effect of various temperatures on the hardness of gray cast iron, the amount of compounding carbon, and the tensile strength. Alloy gray cast iron in the annealing, the more difficult