热浸镀钢材在海水中的氢渗透行为和脆性研究

IOCAS-IR > 海洋环流与波动重点实验室

	热浸镀钢材在海水中的氢渗透行为和脆性研究
其他题名	Hydrogen permeation behavior and embrittlement of hot-dip coated steels exposed to seawater
	刘猛
学位类型	博士
	2008-06-06
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	热浸镀层氢脆慢应变速率拉伸实验
摘要	氢渗透和拉应力的联合作用对海洋环境中的热浸镀钢材的安全构成潜在威胁，本文以当前应用最广泛的三种商业化热浸镀钢材（热浸镀锌、锌-5%铝-稀土和锌-55％铝-1.6%硅）为研究对象，采用Devanathan-Stachurski双面电解池测试技术，测试了自渗氢电流密度曲线，研究了镀层与缺陷比例对氢渗透电流的影响，比较了镀层的氢渗透抑制性能及存在缺陷时的自渗氢能力，并结合镀层成分、结构及其腐蚀机理，探讨了其氢渗透机理；通过慢应变速率拉伸实验，获得了热浸镀钢材在不同充氢条件下的应力-应变曲线，比较了其力学性能参数，并配合断口的显微分析，评价了三种热浸镀钢材在海水中的氢脆敏感性，并对其氢脆机理进行了探讨。主要结果如下： (1) 热浸镀锌镀层的氢渗透抑制能力最弱，锌-5%铝-稀土镀层的氢渗透抑制能力较强，镀层存在缺陷时导致的阴极保护能促进氢渗透；锌-55％铝-1.6%硅镀层的氢渗透抑制能力最强，镀层存在缺陷时基本没有氢渗透电流。当镀层存在缺陷时，氢渗透电流密度的最大值随着镀层与暴露的钢材基体的面积比增大而增大。随着镀层中铝含量的增加，镀层结构越致密，镀层的耐腐蚀性能越好，完整镀层的氢渗透抑制能力越强，镀层存在缺陷时的自渗氢能力越弱。 (2) 热浸镀锌和锌-5%铝-稀土镀层钢材在海水中的氢渗透能明显降低材料的断后延伸率和能量密度，使其断裂方式由韧性转变为准解理；锌-55％铝-1.6%硅镀层在海水中对钢材基体进行阴极保护导致的氢渗透虽能显著降低其断后延伸率和能量密度，但其断裂方式以韧性为主，且断口存在局部的准解理撕裂形貌。随着预浸泡时间的增长，材料充氢量的增加，三种热浸镀钢材的氢脆敏感性提高。随着镀层铝含量的增加，热浸镀钢材在海水中的氢脆敏感性降低。
其他摘要	The security of hot-dip coated steels was imperiled by the synergy of hydrogen permeation and stress in marine environment. In this thesis, three kinds of hot-dip coated steels (Galvanized, Galfan and Galvalume) were used as investigative object. Self hydrogen permeation curves of three hot-dip coated steels were measured using a Devanathan-Stachurski bipolar cell. The effect of the ratio of the area of the exposed steel substrate versus coating surface was investigated. Hydrogen permeation resistance and self hydrogen permeablity when defect existed were compared among three materials. Also, the hydrogen permeation mechanism was analyzed combined with these coatings’ chemical composition and structure and their corrosion mechanism in seawater. The stress-strain curves of these materials with different hydrogen charging conditions were obtained by SSRT, and their mechanical properties was compared. Fractography were also carried out to investigate the effect of hydrogen permeation on the mechanical properties of steel substrate. The results showed that: (1) Hydrogen permeation resistance of Galvanized coating is the lowest, and that of Galfan coating is higher. And when these two kinds of coating have defect, hydrogen absorption and permeation were accelerated. On the contrary, Galvalume coating showed excellent hydrogen permeation resistance, and showed almost no self hydrogen permeation even with defect. Hydrogen permeation flux decreased with the ratio of the area of the exposed steel substrate versus coating surface. With the higher content of aluminum and compacter structure and better corrosion resistance, the coating showed better hydrogen permeation resistance and less self hydrogen permeability. (2) Self hydrogen permeation of Galvanized and Galfan coating in seawater reduced their percentage elongation after fracture and density energy and shift their fracture characteristics from ductile to quasicleavage. The percentage elongation after fracture and density energy of Galvalume coating were also reduced and its fracture characteristics was shift from ductile to locally quasicleavage. With longer hydrogen charging time, the materials showed higher susceptibility to hydrogen embrittlement. With higher content of aluminum and better corrosion resistance, the coating showed lower susceptibility to hydrogen embrittlement in seawater.
页数	68
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/585
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	刘猛. 热浸镀钢材在海水中的氢渗透行为和脆性研究[D]. 海洋研究所. 中国科学院海洋研究所,2008.

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