均匀腐蚀海工结构钢拉伸试验研究

Experimental Study on the Tensile Properties of Uniform Corroded Marine Structure Steel

根据电化学腐蚀原理,制备不同均匀腐蚀程度的海工高强度结构钢NVD36试件,对腐蚀试件进行了拉伸试验,得到了钢材拉伸性能的变化规律:随着腐蚀程度的增加,钢材NVD36的弹性模量、屈服强度、屈服应变、极限强度、峰值应变、断裂强度和断裂应变(极限应变)都在逐渐变小,屈服平台长度和强化应变没有明显的变化趋势,强屈比保持在一定范围内。当腐蚀质量相同,试件出现明显点蚀时,NVD36钢材的拉伸性能有所退化。通过拟合试验数据,建立了腐蚀后海洋结构钢应力-应变三折线模型,并对拉伸试验进行了数值模拟。

Referring to the electrochemical corrosion principle,specimens made of marine high strength structure steel NVD36 with different degrees of uniform corrosion are prepared through laboratory accelerated corrosion test.Tension tests conforming to GB/T228.1 were imposed on all corroded specimens,and the changing rules of the NVD36 tensile properties were mentioned as followed:as the corrosion degree deepens,the elasticity modulus,yield strength,yield strain,ultimate strength,peak strain,breaking strength,as well as breaking strain(ultimate strength)have a downward tendency,while the harden strain and yield plateau length have no rules,and the yield ratio changes in a certain range.Having same corrosion mass but different corrosion types leads to different tensile properties,and worse properties will occur if the pitting corrosion exists.A triliner corroded stress-strain model of NVD36 was set up through fitting the data obtained from the tension tests.The triliner corroded stress-strain model contains elastic segment,yield plateau and hardening segment.And numerical calculations were applied to simulate the tension experiments,which are almost close to the experiment measured data and can be applied to evaluate the strength of corroded platform in engineering practice.However,the numerical simulation can only show the changing trend of stress-strain relationship when the specimen is under tension loading rather than the precise value which equals to the experiment measured value.