对水压爆破试验合格与不合格的两个汽车用长纤维增强聚丙烯复合材料进气歧管焊接接头进行了拉伸试验, 观察了人工断口形貌并分析了影响其性能的主要因素。结果表明: 水压爆破试验合格进气歧管焊接接头的拉伸强度约为11 MPa, 远小于母材的; 热影响区及熔合区中的纤维呈无序分布, 且与基体聚丙烯结合较好, 但是纤维出现了聚集情况, 且部分纤维剥落, 导致焊接接头拉伸强度的降低。水压爆破试验不合格进气歧管焊接接头熔合区纤维与基体聚丙烯的结合很差, 且存在大量破碎现象; 破碎纤维所在区域在水压爆破试验时成为裂纹源, 导致焊缝开裂。

The tensile test was conducted on the intake manifold welded joints of the long-fiber reinforced polypropylene composite, one of which passed the hydraulic burst test and the other didn′t. The artificial fracture morphology was observed and the influence factors on the properties were analyzed. The results show that the tensile strength of the intake manifold welded joint that passed the hydraulic burst test was about 11 MPa, which was much lower than that of the base metal; the fibers in the heat affected zone and fusion zone showed a disorder distribution and combined with the polypropylene substrate well; but the aggregation of the fibers occurred and some were peeled off, resulting in the decrease of the tensile strength of the welded joint. The combination of the fibers and polypropylene substrate of the intake manifold welded joint that didn′t pass the hydraulic burst test was very bad and a large number of broken fibers were observed; the broken fiber area became the crack initiation and led to the crack of the weld.