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Effect of Environmental variations on Hydrogen Embrittlement of High Strength Steels

环境变化对高强度钢氢脆的影响

基本信息

批准号：
07650773
负责人：
MAGUMO Michihiko
金额：
$ 1.22万
依托单位：
Waseda University, School of Science and Engineering
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650773/
关键词：
High Strength Steel Hydrogen Embrittlement Delayd Fracture PC Ban Hydrogen Analysis Environmental Degradation 水素昇温分析鉄鋼水素分析

项目摘要

The enhanced reduction of delayd fracture life by the environmental variations has been revealed with Prestressed Concrete steel bars. Applied load and external hydrogen potential were employed as the environmental parameters to be varied. Maximum load or potential were kept constant for the variations, and the degradation was evaluated by means of slow elongation rate tensile test and constant stress tests. The environmental variations dis not affect the amount or rate of hydrogen absorption, in contradictory to the former concepts that the load variation destroys the protective surface layr. The variation of hydrogen potential did not altered the diffusion constant of hydrogen which was evaluated from the absorption and desorption rates.In order to examine the origin of the environmental variation effects, hydrogen thermal desorption spectroscopy was conducted. Two types of hydrogen exist in the weekly trapped hydrogen which desorbs at about 1000ﾟC,one is the hydrogen the amount of which increases with plastic deformation and the other is trapped a the intrinsic microstructures such as precipitates. From hydrogen thermal desorption spectroscopy of specimens subjected to plastic deformation and successive annealing at low temperatures as low as 200ﾟC,it was revealed that the trapping sites of hydrogen which increase with plastic deformation was point defects. Thermal desorption of hydrogen at 200ﾟC is the consequence of annealing out of point defects during heating. The effect of the environmental variations is likely to result in the increase of the defect density which is annealed out during heating. A new theory has been proposed that the hydrogen embrittlement of steels is induced by the defects which are introduced by plastic deformation and stabilized by hydrogen. The variance of environment enhances this effect.

预应力混凝土钢筋的延迟断裂寿命随环境变化而降低。以外加负荷和外加氢势为环境参数进行了试验研究。最大载荷或电位保持不变的变化，并通过缓慢拉伸试验和恒定应力试验的手段进行评估的降解。环境变化不影响吸氢量或吸氢速率，这与以前认为负荷变化会破坏保护表面层的观点相矛盾。氢势的变化并没有改变氢的扩散常数，这是从吸收和解吸速率来评估的。为了检查环境变化影响的来源，进行了氢热解吸光谱。在约1000 ℃时解吸的微量氢中存在两种类型的氢，一种是随着塑性变形而增加的氢，另一种是被本征微观结构如沉淀物捕获的氢。从经过塑性变形和在低至200 ℃的低温下连续退火的试样的氢热脱附谱中发现，随着塑性变形而增加的氢捕获位点是点缺陷。氢在200 ° C下的热解吸是加热过程中退火点缺陷的结果。环境变化的影响可能导致在加热期间退火的缺陷密度的增加。提出了钢的氢脆是由塑性变形引入的缺陷引起的新理论。环境的变化增强了这种效应。