On the basis of experiments, two kinds of butt joint forming physical models and three types of dimple models of fractography have been proposed. These models reveal the essence of welding process and the forming mechanism of white speck.

• 在试验研究的基础上,提出了两种形式的接头形成物理模型和3种类型的接头断口韧窝模型,由此可揭示接头的形成木质和“白斑”形成机制。