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研究了U-2.5%Nb合金(质量分数,下同)在相对湿度分别为3.5%、50%、100%、水浸、热水和水蒸气环境,氢气压力分别在0.4,1.0,2.0MPa条件下的拉伸性能及断口形貌。结果表明:拉伸速率在3×10-5/s时,随环境湿度及氢气压力的增加,U-2.5%Nb合金的抗拉强度降低,规定非比例延伸强度增加,塑性急剧下降。同样在水浸环境,3×10-5/s与1×10-4/s的拉伸速率相比,U-2.5%Nb合金断后伸长率下降约84%,断面收缩率下降约79%。拉伸速率在3×10-5/s时,合金在2.0与0.4MPa的氢气压力相比,断后伸长率下降约20%,断面收缩率下降约13%。在相对湿度3.5%的环境下,U-2.5%Nb合金试样断口边缘呈韧窝状,有一定的韧性特征。在水浸环境下,试样断口边缘韧窝明显减少,有一定的脆断特征。在水蒸气环境中,试样断口边缘有明显的解理脆断特征。在氢气环境中,试样断口的脆断特征随氢气压力的增加而增强。
The results show that under the conditions of water immersion, hot water and steam environment, the hydrogen pressures are respectively 0.4, 1.0 and 2.0 MPa under the conditions of relative humidity of 3.5%, 50%, 100% Under the tensile properties and fracture appearance. The results show that the tensile strength of U-2.5% Nb alloy decreases with the increase of ambient humidity and hydrogen pressure at a tensile rate of 3 × 10-5 / s, which indicates that the non-proportional tensile strength increases and the plasticity decreases sharply. Also in the flooding environment, the elongation at break of U-2.5% Nb alloy decreased by about 84% and the reduction of area decreased by about 79% at 3 × 10-5 / s and 1 × 10-4 / s. . When the drawing rate is 3 × 10-5 / s, the elongation at break of the alloy decreases about 20% and the reduction of area shrinkage by about 13% at 2.0 compared with the hydrogen pressure of 0.4MPa. Under the relative humidity of 3.5%, the fracture edge of the U-2.5% Nb alloy specimen has a dimpled shape with certain toughness characteristics. In the flooding environment, the edge of the specimen fracture dimples significantly reduced, there is a certain brittle fracture characteristics. In the water vapor environment, the edge of the specimen fracture has obvious cleavage brittle fracture characteristics. In the hydrogen environment, the brittle fracture characteristics of the specimen fracture increase with the increase of hydrogen pressure.