聚乙烯管道热熔接头卷边对拉伸性能的影响

Effect of Butt Fusion Welding Beads on Tensile Properties of Polyethylene Pipes

通过拉伸试验,研究了聚乙烯管道热熔对接接头不同卷边情况试样的失效形式、拉伸强度和拉伸历程。研究发现,带卷边试样卷边与管壁之间形成的凹槽尖端应力集中严重,拉伸时裂纹逐渐扩展直至试样断裂;而不带卷边试样拉伸时,试样发生大变形后在焊缝及其与管材交界面出现脆断现象。不带卷边试样的拉伸强度明显高于带卷边试样,其断裂伸长率也远高于带卷边试样,拉伸速率为10mm/min时,拉伸强度差值为27%左右,断裂伸长率差值在100%以上。结果表明,去除热熔对接接头双侧卷边可显著提高其拉伸力学性能,而去除单侧卷边对其力学性能仅有轻微改善。

Tensile tests were carried out to investigate the failure mode, tensile strength, and tensile process of polyethylene pipe samples with different weld bead situations. It was found that, the failure mode of samples with weld beads was crack propagation because of the stress concentration around the notch tip between weld beads and the pipe, and a phenomenon of brittle fracture was observed after large deformation in tensile process of samples without beads. The tensile strength and elongation at break of the samples without weld beads were much higher than that with weld beads, and the difference would be no less than 27 % and 100 % respectively with a tensile rate of 10 mm/min. It demonstrated that the removal of both butt fusion weld beads could improve its tensile properties notably, but it would be improved slightly when just one of them was removed.