一、引言螺栓断裂是高温高压电厂比较普遍存在的问题之一。螺栓断裂,常常会引起人身和设备的损伤,直接影响电厂的安全运行。螺栓在运行中产生的裂纹,大多数是从螺栓外表面开始,逐渐向中心发展(有些螺栓由于拆装时中心孔用火烤时工艺不慎,而产生从螺栓中心孔开始逐渐向外表面发展的裂纹)。裂纹断面一般与螺栓端面近似平行。这种裂纹都是产生于螺纹根部位置。过去为了检查这种螺栓裂纹,许多电厂都采用拆下螺栓,然后作磁力探伤或者萤光探伤(或者着色探伤)。但是,采用这种方法有以下几个缺点: I. Introduction Bolt breakage is one of the more common problems in high-temperature and high-pressure power plants. Bolt fracture, often cause personal and equipment damage, a direct impact on the safe operation of power plants. Bolts in the operation of the cracks, mostly from the outer surface of the bolt, and gradually to the center (some bolts due to disassembly center hole with fire roasted careless process, resulting from the bolt center hole began to gradually develop to the outer surface Of the crack). The fracture surface is generally parallel to the end face of the bolt. This crack is generated in the root position of the thread. In the past, in order to check for such bolt cracks, many power plants used bolts to remove them and then make magnetic or fluorescent tests (or color tests). However, there are several disadvantages to using this method: