锅炉奥氏体不锈钢的小径管弯管段易发生应力腐蚀开裂进而引发泄漏，超声检测时存在晶粒粗大、接触面小且曲率大等技术难点。以某火电厂屏式过热器管弯管内壁检测为例，通过检测探头的设计和选用、参考试块的设计和制作、灵敏度及评判方法的确定等确定了奥氏体不锈钢小径管弯管段具体的检测工艺。将实际检测结果和金相检验结果进行对比，结果表明该检测方法可有效检测奥氏体不锈钢小径管弯管段的内壁裂纹。

The bent section of the austenitic stainless steel small diameter pipe of the boiler is susceptible to stress corrosion cracking and leakage. For ultrasonic testing, there are technical difficulties such as coarse grains, small contact surfaces and large curvature. Taking the detection of the inner wall of the bent pipe of a screen superheater in a thermal power plant as an example, the specific detection process could only be determined through the design and selection of the detection probe, the design and manufacture of the reference test block, and the determination of sensitivity and the evaluation method. The comparison between actual test results and physical anatomy shows that the test method can effectively detect cracks on the inner wall of the austenitic steel small diameter pipe bend.