【摘要】 对两种不同厚度的Q345钢材和Ⅱ级对接焊缝连接件分别进行了落锤冲击动态拉伸试验,并与相同规格钢材试件静态拉伸试验结果进行了对比,研究了应变率对钢材和对接焊缝的破坏形态、屈服强度、极限强度及伸长率等动态拉伸力学性能指标的影响规律。试验结果表明,钢材在动态拉伸时表现出脆性断裂破坏趋势;对接焊缝连接件的破坏发生在母材区,焊缝保持完整,因此II级及以上对接焊缝试件的强度和延性可视为与母材相同。与静力拉伸试验结果相比,10mm厚钢材的伸长率稍有增大,断面收缩率变化不大;18mm厚钢材的伸长率变化不大,断面收缩率明显减小。随着应变率的增大,两种厚度钢材的屈服强度和极限强度有一定程度的提高,而伸长率和断面收缩率有降低的趋势。更多还原

【Abstract】 Tensile coupon tests on Q345 steel and butt-weld joints with two different thickness are conducted under drop-hammer impact loading.Results from dynamic tests are compared with those from static tests to investigate the influence of strain rate on failure mode,yield strength,ultimate strength and elongation of the specimen.The test results show that steel plates tend to fail in a brittle fracture mode under tensile impact loading,and the butt-welded joint specimens fail at base metal section where the butt weld remains intact.Therefore,the strength and ductility of butt weld with grade II or higher grade welding quality are almost the same as base material.Compared with static tensile test,the dynamic elongation of 10 mm steel plate has a slight increase but the reduction of cross-sectional area has negligible change;while the dynamic elongation of 18 mm steel plate has small change but the reduction of cross-sectional area decreases obviously.With increase in strain rate,the yield strength and ultimate strength of steel are enhanced in certain degree.However,the elongation and reduction of cross-sectional area tend to decrease.更多还原