410 MPa级钢制无缝压力管在高温拉伸测试中出现了结果异常现象，具体表现为随着试验温度的升高，材料的屈服强度先升高后下降，与此同时，材料的抗拉强度随试验温度的变化也表现出相似的变化规律，且两者分别在150，200℃时达到最大。通过多种检验手段对无缝压力管的微观组织变化进行了研究，发现所述试验现象是试验温度与晶粒尺寸综合作用的结果。

The abnormal phenomenon in the high temperature tensile test of seamless pressure tube made of 410 MPa grade steel is shown as follows:the yield strength of the corresponding material increases first and then decreases, as the test temperature increases. At the same time, the tensile strength values show similar abnormalities with the change of test temperature, what's more, the maximum is at 150, 200℃, respectively. The changes of microstructure for seamless pressure tube were studied by various means. It was found that the experimental phenomena were the result of the combined effect of test temperature and grain size.