采用超声冲击技术对果子沟大桥Q370qE桥梁用钢焊接对接接头进行了全覆盖超声冲击处理(Ultrasonic Im-pact Treatment,UIT),并通过XRD、红山-10T型高频疲劳试验机等对UIT前后Q370qE焊接接头的表明形貌、残余应力、疲劳性能的变化进行了测试和分析。结果表明,UIT使左焊趾附近的残余压应力由-25.6 MPa增高达-240.8MPa,使右焊趾附近17.2MPa的残余拉应力转变为-196.3MPa的残余压应力;使焊接接头在应力R比为-1,应力范围为±270MPa的条件下,其疲劳寿命为22954,经超声冲击处理后焊接接头在相同条件下其疲劳寿命为46523。对比未处理试样,UIT处理试样的疲劳寿命至少提高了1倍多。 The Ultrasonic Im-pact Treatment (UIT) was applied to the welded joint of Q370qE bridge in Guozigou Bridge by ultrasonic impact technique. The X-ray and the Hongshan-10T high- Q370qE welded joints show the morphology, residual stress, fatigue properties of the changes were tested and analyzed. The results show that the UIT increases the residual compressive stress near the left toe by -25.6 MPa up to -240.8 MPa and the residual tensile stress at 17.2 MPa near the right toe to the residual compressive stress of -196.3 MPa. The fatigue life of the welded joint under the same conditions was 46523 under the condition of the ratio of -1 and the stress range of ± 270MPa. Compared with the untreated sample, the fatigue life of the UIT treated sample has more than doubled at least.