Any of various ovens for hardening, burning, or drying substances such as grain, meal, or clay, especially a brick-lined oven used to bake or fire ceramics.
窑用于加硬，燃烧或烘干物料如谷物、粗粉或粘土的各式的小窑，特指用来焙干或烧陶器的砖砌的窑
So we find that hardening operation is made up of heating and quenching.
因此我们发现淬火工序包括加热和淬硬两个步骤。
hardening means make harder.
淬火就是促使变硬。
