ABSTRACT

The influence of temper temperature on the environment assisted cracking of seamless 9% Ni steel tubes were investigated using scanning electron microscope (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), slow strain rate tensile (SSRT) tests, hydrogen permeation tests and electrochemical measurements. Mechanical and electrochemical tests were conducted in sodium thiosulphate (Na₂S₂O₃ 10⁻³ mol L⁻¹) solution at open circuit potential (OCP) and at cathodic potential. Results showed that 9% Ni steel had a higher ductility loss at OCP when compared with the results obtained under cathodic potential. The lower ductility loss at cathodic potential was attributed to the inhibition of the anodic dissolution. After the tests, the specimens were examined using scanning electron microscopy to characterise the fracture morphology. The fracture surface exhibited mixed morphology, with a ductile morphology in the centre and a brittle morphology near the edges.

摘要

使用扫描电子显微镜（SEM），电子背散射衍射（EBSD），X射线衍射（XRD）和慢应变速率拉伸（SSRT）测试研究了回火温度对9％Ni无缝钢管环境辅助开裂的影响，氢渗透测试和电化学测量。在硫代硫酸钠（Na ₂ S ₂ O ₃ 10 ^-3 mol L ^-1）在开路电势（OCP）和阴极电势下的解决方案。结果表明，与在阴极电势下获得的结果相比，9％的Ni钢在OCP处具有更高的延展性损失。阴极电位下较低的延展性损失归因于阳极溶解的抑制。试验后，使用扫描电子显微镜检查样品以表征断裂形态。断裂表面表现出混合的形态，在中心具有延性形态，在边缘附近具有脆性形态。