摘要:
对Q355GNH耐候钢开展了模拟工业海洋大气腐蚀环境乙酸盐雾试验,分析了其耐蚀性能,并通过单调拉伸试验研究腐蚀率对其力学性能指标退化的影响规律,建立了6、14 mm厚度的耐候钢锈损本构关系模型。研究结果表明:腐蚀导致耐候钢强度降低、延伸率减小,其中腐蚀率对断裂应变的影响最大,其次是屈服强度和极限强度,腐蚀后耐候钢屈强比稳定,拉伸断裂形式仍为韧性断裂;钢材厚度越小,腐蚀后钢材承载力下降越明显;随着腐蚀率增加,钢材应力-应变曲线的屈服平台、塑性强化阶段缩短,腐蚀40天后6 mm厚板件的屈服平台消失。基于未腐蚀耐候钢本构关系,通过引入参数k1、k2、k3、C,提出了相应厚度的锈蚀耐候钢本构模型,与试验获得的应力-应变曲线各阶段吻合良好。
Abstract:
In this study, acetic acid salt spray test was carried out on Q355GNH weathering steel, and its weathering performance in industrial marine atmospheric corrosion environment was analyzed. After the corrosion tests, the monotonic tensile test was carried out to study the degradation trend of the mechanical properties of pre-corroded Q355GNH with the increase of corrosion rate, and the corrosion damage constitutive model of Q355GNH with 6 mm and 14 mm thickness was established. The results showed that the tensile strength and elongation of the weathering steel decreased after corrosion. The corrosion rate had the greatest influence on the fracture strain, followed by the yield strength and ultimate strength; the yield ratio of weathering steel was always stable after corrosion, and the tensile fracture mode was still ductile fracture; the smaller the thickness of steel was, the more obvious the decrease of mechanical properties of steel after corrosion was; with the increase of corrosion time, the constitutive curve of Q355GNH steel changed, the yield platform and plastic strengthening stage gradually became shorter, and the yield platform of 6 mm material specimen disappeared just after 40 days of corrosion. Based on the constitutive model of Q355GNH weathering steel with smooth surface, the constitutive model of pre-corroded weathering steel was proposed by introducing parameters k1, k2, k3, C, which was in good agreement with the constitutive curve of Q355GNH after corrosion.
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