中文摘要：

以某汽车传动轴为对象，试验研究双向应力状态和给定的热处理工艺条件下材料试样的低载强化特性与规律。研究结果表明，双向应力下该材料试样仍然具有明显强化效果；经过最佳强化载荷和强化次数强化后，材料的疲劳寿命可以提高120％，疲劳强度提高大约14％；与单向应力状态下的低载强化特性相比，虽然双向应力状态下具有强化作用的强化次数和强化载荷、最佳强化次数和强化载荷有明显下降，但强化效果没有明显下降；最后就应力状态对低载强化特性影响的原因进行分析。

英文摘要：

In order to investigate the strengthening characteristics under low-amplitude loads of universal material in biaxial stress, the strengthening tests of middle shaft of constant velocity joint were conducted. The strengthening effect under lowamplitude loads of universal material in biaxial stress are obviously showed in this experiment. By strengthening under a best strengthening loads and strengthening cycles, fatigue strength and life of material can be increased by 14 and 120 percents, respectively. Compared with the strengthening characteristics in uniaxial stress, the strengthening effect wasn＇t obviously decreased though the strengthening loads, strengthening cycles and best strengthening loads, strengthening cycles were obviously decreased. The preliminary reasons of influencing the strengthening under low amplitude loading for different stress were analyzed.