高强耐蚀钢材料力学特性试验研究

海洋钢结构的腐蚀劣化是导致结构失效的关键因素,应用耐蚀钢材可以显著提升结构服役寿命。通过对高强耐蚀钢的力学特性开展研究,进行了一系列单调和循环加载力学性能试验,分析了高强耐蚀钢在单调和循环荷载作用下的破坏形态、应力-应变关系、延伸率等性能,研究了循环加载历史、应变幅值和应变增量等参数对材料力学性能的影响。结果表明:高强耐蚀钢在单调加载下无明显屈服平台,断后伸长率在16%～19%之间;循环加载下,钢材循环应力-应变关系随加载圈数增加表现为先强化、后软化、最终逐渐趋于稳定;不同应变幅值软化因子呈近似线性变化,其值较小且加载后期幅值影响不显著;单次循环的能量耗散值随着应变幅值增大而显著增大,但其增大倍率呈近似线性下降趋势,变幅应变加载造成材料损伤程度较常幅应变加载更严重;可采用Rasmussen模型和Ramberg-Osgood模型分别描述高强耐蚀钢单调加载力学行为和循环加载力学行为。

Experimental research on mechanical characteristics of high-strength corrosion resistant steel

Corrosion deterioration of offshore steel structures is the key factor leading to structural failure，and the service life of offshore structures can be significantly improved by using corrosion resistant steel. In this research, the mechanical properties of a high-strength corrosion resistant steel were studied, and a series of monotonic and cycle loading tests were conducted. The failure mode, stress-strain relationship, and elongation rate of the steel under monotonic and cyclic loadings were analyzed, the effects of cyclic loading history, strain amplitude, stress amplitude and strain increment on mechanical properties were discussed. Research results show that all the stress-strain curves of the high-strength corrosion resistant steel specimens have no obvious yield platform, and the elongation after fracture ranges from 16% to 19% under monotonic loading. The cyclic stress-strain relationship of the steel shows firstly cyclic hardening and then cyclic softening with increase of loading cycles, and finally becomes stable. The softening factors of different strain amplitudes vary approximately linearly, and their values are small and the influence of amplitudes is not significant.With the increase of strain amplitude,the energy dissipation value of single cycle increases significantly，and its growth rate per unit amplitude decreases approximately linearly. The material damage caused by variable amplitude strain loading is more serious than that caused by constant amplitude strain loading. Rasmussen model and Ramberg-Osgood model can be used to describe the mechanical behavior of high-strength corrosion resistant steel under monotonic loading and cyclic loading respectively.