定义：钎焊是一种固相连接工艺，在高于钎料熔点、低于母材固相线的温度条件下，利用熔融钎料填充接头间隙，实现母材冶金结合的连接技术。按温度区分，450℃以上为硬钎焊，450℃以下为软钎焊。

Definition: Brazing is a solid-state joining process. At a temperature above the melting point of filler metal but below the solidus temperature of base metals, molten filler metal fills the joint gap to form a metallurgical bond between base materials. It is classified into brazing (above 450°C) and soldering (below 450°C).

原理：加热至工艺温度时，钎料熔化而母材保持固态；依靠润湿性与毛细作用，液态钎料自发铺展、渗入母材接头缝隙；随后冷却凝固，在钎料与母材界面形成冶金结合层，从而实现工件的牢固连接。接头品质核心取决于钎料对母材的润湿能力与接头间隙带来的毛细效应。

Principle: Upon heating to the process temperature, the filler metal melts while the base metals remain solid. Driven by wettability and capillary action, the liquid filler metal spontaneously spreads and penetrates the joint clearance. After cooling and solidification, a metallurgical bonding layer forms at the interface between filler and base metal, achieving permanent joining. The joint performance mainly depends on the wettability of filler metal on base metals and capillary effect from joint clearance.