在取自未服役与服役5万h HR3C钢管的拉伸试样上预制不同类型（V型、U型）、不同底部曲率半径（0.10，0.13，0.25，0.85 mm）和不同长度（0.25，0.50，0.75，1.00 mm）的缺口，通过拉伸试验研究了钢管的缺口敏感性。结果表明：未服役HR3C钢管无缺口敏感性，服役后钢管发生脆化，对缺口较为敏感；脆化态钢管对V型缺口的敏感性大于对U型缺口的，特别是对角度较大、底部曲率半径较小（0.10～0.25 mm）、长度较长（0.50～1.00 mm）的V型缺口较为敏感；当缺口应力集中系数大于3.5时，脆化态HR3C钢管的缺口敏感性较大。

Notches with different types (V, U), different root curvature radii (0.10, 0.13, 0.25, 0.85 mm) and different length (0.25, 0.50, 0.75, 1.00 mm) were pre-made in tensile samples from HR3C steel tube before and after service for 50 000 h, and then the notch sensitivity of the steel tube was studied by tensile tests. The results show that the unserviced HR3C steel tube had no notch sensitivity. After service, the steel tube was embrittled, and therefore became sensitive to notches. The embrittled steel tube had higher sensitivity to the V-notch than to the U-notch, especially being sensitive to the V-notches with a relatively large angle, relatively small root curvature radii (0.10-0.25 mm) and relatively long length (0.50-1.00 mm). When the stress concentration factor was greater than 3.5, the notch sensitivity of embrittled HR3C steel tube was high.