固溶温度对双相不锈钢腐蚀行为和氢脆敏感性的影响
发布时间：2018-09-16 21:44
【摘要】：铁素体(α)和奥氏体(γ)两相组成的2205双相不锈钢由于铁素体相的存在而具备优良的机械性能,由于奥氏体相的存在而具备很好的耐蚀性能。这种优良的综合性能使之广泛应用于海洋建筑、储酸设备、输油输气管道等领域。然而在其服役的过程中,由于服役环境中杂质离子的存在以及人为施加的保护措施,如阴极保护过程,导致氢等杂质离子进入内部,在应力的共同作用下,导致2205双相不锈钢出现脆性开裂,造成严重的后果,带来不可预估的损失。材料的组织决定其性能,因此,对2205双相不锈钢微观组织与腐蚀行为和氢脆敏感性关系的研究具有很大的理论与实际意义。本文通过改变固溶温度的方式控制2205双相不锈钢的微观组织,利用显微组织和显微硬度分析、电化学分析测试(极化曲线,电化学阻抗)、慢应变速率拉伸、氢渗透以及扫描电镜观测的方法研究微观组织对2205双相不锈钢的腐蚀行为以及氢脆敏感性的影响。固溶处理实验结果表明:当固溶温度处于1000℃至1200℃之间时,2205双相不锈钢组织中只存在铁素体相与奥氏体相,不存在σ、CrN等第二相,铁素体相比例随固溶温度的升高呈线性升高关系,而奥氏体相则呈相反规律。当固溶温度为1050℃时,两相比例最接近1:1,此时材料显微硬度最低,并且随着固溶温度的升高,显微硬度增大。硫酸溶液电化学测试结果表明:2205双相不锈钢在0.5M硫酸溶液中具有明显的钝化区间,且当温度为1050℃时,材料耐蚀性最好,钝化膜致密度最高,2205双相不锈钢在0.5M硫酸溶液中的整个阳极过程都不存在应力腐蚀敏感性。应力腐蚀拉伸结合拉伸过程阻抗谱结果表明:阴极充氢导致2205双相不锈钢表面钝化膜恶化,其氢脆敏感性也大大增加;氢脆敏感性与相比例密切相关,当两相比例接近1:1时,材料的氢脆敏感性最低,且随着两相比例差异的变大,氢脆敏感性大大增加;在0.5M硫酸溶液的慢应变拉伸过程中氢脆裂纹经历萌生-发展-钝化的过程,奥氏体相作为“氢陷阱”阻碍氢扩散。单一相耐蚀性能实验结果表明:2205双相不锈钢两相耐蚀性能与各自相组成元素的含量密切相关,当温度为1050℃时,铁素体单相与奥氏体单相的耐蚀性能达到最佳。在3.5%氯化钠溶液中,铁素体相耐蚀性高于奥氏体相,奥氏体相优先腐蚀,在0.5M硫酸溶液中,两相耐蚀性差异不明显,趋于均匀腐蚀。氢渗透结果表明:随着固溶温度的升高,2205双相不锈钢整体的氢扩散系数增加,单相铁素体的氢扩散系数增加以及铁素体含量的升高导致2205双相不锈钢氢脆敏感性变大。
[Abstract]:The 2205 duplex stainless steel composed of ferrite (伪) and austenite (纬) has excellent mechanical properties due to the existence of ferrite phase and good corrosion resistance due to the existence of austenite phase. This excellent comprehensive performance makes it widely used in ocean building, acid storage equipment, oil and gas pipeline and other fields. However, in the course of service, due to the presence of impurity ions in the service environment and artificial protective measures, such as cathodic protection, impurity ions such as hydrogen enter into the interior, under the joint action of stress. It leads to brittle cracking of 2205 duplex stainless steel, resulting in serious consequences and unpredictable losses. The microstructure of 2205 duplex stainless steel depends on its properties. Therefore, it is of great theoretical and practical significance to study the relationship between microstructure and corrosion behavior and hydrogen embrittlement sensitivity of 2205 duplex stainless steel. In this paper, the microstructure of 2205 duplex stainless steel was controlled by changing the solution temperature. The microstructures and microhardness were analyzed, electrochemical analysis (polarization curve, electrochemical impedance), slow strain rate stretching, The effect of microstructures on corrosion behavior and hydrogen embrittlement sensitivity of 2205 duplex stainless steel was investigated by hydrogen permeation and scanning electron microscopy. The experimental results of solution treatment show that there are only ferrite phase and austenite phase in the microstructure of T2205 duplex stainless steel when the solution temperature is between 1000 鈩，
本文编号：2244904
[Abstract]:The 2205 duplex stainless steel composed of ferrite (伪) and austenite (纬) has excellent mechanical properties due to the existence of ferrite phase and good corrosion resistance due to the existence of austenite phase. This excellent comprehensive performance makes it widely used in ocean building, acid storage equipment, oil and gas pipeline and other fields. However, in the course of service, due to the presence of impurity ions in the service environment and artificial protective measures, such as cathodic protection, impurity ions such as hydrogen enter into the interior, under the joint action of stress. It leads to brittle cracking of 2205 duplex stainless steel, resulting in serious consequences and unpredictable losses. The microstructure of 2205 duplex stainless steel depends on its properties. Therefore, it is of great theoretical and practical significance to study the relationship between microstructure and corrosion behavior and hydrogen embrittlement sensitivity of 2205 duplex stainless steel. In this paper, the microstructure of 2205 duplex stainless steel was controlled by changing the solution temperature. The microstructures and microhardness were analyzed, electrochemical analysis (polarization curve, electrochemical impedance), slow strain rate stretching, The effect of microstructures on corrosion behavior and hydrogen embrittlement sensitivity of 2205 duplex stainless steel was investigated by hydrogen permeation and scanning electron microscopy. The experimental results of solution treatment show that there are only ferrite phase and austenite phase in the microstructure of T2205 duplex stainless steel when the solution temperature is between 1000 鈩，
本文编号：2244904
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