强腐后Q345钢力学性能退化试验

系统研究了强腐后Q345钢表面形貌和腐蚀时间对其力学性能退化的影响；采用浓度36%工业盐酸在室温环境下快速腐蚀的方法，设计了腐蚀时间分别为0、1、2、4、8、12、24、48、72 h的9组钢试件；采用三维非接触激光扫描仪和扫描电镜扫描腐蚀钢，测量了最大蚀坑宽度、高度和腐蚀试件厚度，计算了最大蚀坑影响系数；开展了拉伸试验，结合扫描形貌与微观组织形态解释了强腐后Q345钢的力学性能退化机理；建立了浓度36%工业盐酸在室温环境强腐后Q345钢的腐蚀动力学曲线和本构关系模型，揭示了强腐后Q345钢的力学性能退化规律。研究结果表明:随着腐蚀时间的增加，Q345钢的腐蚀动力学曲线展示了腐蚀率的变化规律；腐蚀时间在1 h以内，最大蚀坑影响系数增大最为明显，钢的名义屈服强度、名义抗拉强度、名义弹性模量和伸长率退化较大，分别达到未腐蚀钢的3.00%、0.69%、1.99%和4.88%；当腐蚀时间超过12 h，最大蚀坑影响系数增加缓慢，钢的名义屈服强度、名义抗拉强度、名义弹性模量和伸长率退化较为缓慢，分别达到未腐蚀钢的7.58%、4.02%、10.27%和26.64%；随着最大蚀坑影响系数和腐蚀时间的增加，屈强比变化较小；在腐蚀试件的应力-应变本构关系曲线中，随着腐蚀时间的增加，钢材的屈服平台逐渐缩短甚至消失，钢材由延性破坏转变为脆性破坏。 

Experiment on mechanical property degradation of Q345 steel after strong corrosion

The influences of surface morphology and corrosion time of Q345 steel after strong corrosion on its mechanical property degradation were systematically studied. A rapid corrosion method based on the industrial hydrochloric acid with a concentration of 36% at room temperature was adopted, and nine groups of steel specimens with the corrosion time of 0, 1, 2, 4, 8, 12, 24, 48, and 72 h respectively were designed. A 3D non-contact laser scanner and an electron microscope were adopted to scan the corroded steel, and the width and height of the largest corrosion pit and the thicknesses of corroded specimens were measured. The influence coefficient of the largest corrosion pit was calculated. A tensile test was carried out, and the mechanical property degradation mechanism of Q345 steel after strong corrosion was explained according to the scanning morphology and microstructure morphology. The corrosion kinetics curve and constitutive relation model of Q345 steel after strong corrosion by the industrial hydrochloric acid with a concentration of 36% were established at room temperature, and the mechanical property degradation law of Q345 steel after strong corrosion was revealed. Research results show that as the corrosion time increases, the corrosion kinetics curve of Q345 steel demonstrates the change law of corrosion rate. When the corrosion time is less than 1 h, the influence coefficient of the largest corrosion pit increases obviously, and the nominal yield strength, nominal tensile strength, nominal elastic modulus and elongation of the steel degrade significantly, reaching 3.00%, 0.69%, 1.99%, and 4.88% of the uncorroded steel respectively. When the corrosion time exceeds 12 h, the influence coefficient of the largest corrosion pit increases slowly, and the nominal yield strength, nominal tensile strength, nominal elastic modulus and elongation of steel degrade slowly, reaching 7.58%, 4.02%, 10.27%, and 26.64% of the uncorroded steel respectively. The change of the yield-strength ratio is slight as the influence coefficient of the largest corrosion pit and the corrosion time increase. In the stress-strain constitutive relation curves of the corroded specimens, as the corrosion time increases, the yield platform of steel gradually shortens or even disappears, and the steel changes from ductile failure to brittle failure.