研究了变拘束试验方法条件下产生的焊缝热裂纹断口形貌的形成机理及影响因素。结果表明，该方法所导致的热裂纹断口形貌分为四种类型：Ａ型区、Ｄ型区、ＤＦ型区及Ｆ型区。而四个区的形成机理和尺寸大小主要和试验中的应变速率相关。在较高的应变速率条件下，ＤＦ型区、Ｆ型区尺寸明显减小，而Ｄ型区尺寸增大。这主要是由于高应变速率促使晶内变形而抑制晶间变形所致 The forming mechanism and influencing factors of the fracture morphology of weld hot cracking under the condition of variable restraint test were studied. The results show that the fracture morphology of hot cracks caused by this method can be divided into four types: A type, D type, DF type and F type. The formation mechanism and size of the four zones are mainly related to the strain rate in the experiment. Under the condition of higher strain rate, the sizes of DF type and F type are obviously reduced while the size of D type is increased. This is mainly due to the high strain rate to promote intragranular deformation and inhibit intergranular deformation