An evaluate method for hydrogen embrittlement property of high strength steel sheet has been proposed in this study. To take into consideration of the effect of plastic strain in addition to the effects of applied/residual stress and diffusible hydrogen, U-bend specimens have been adopted because steel sheets for automobiles are usually used after press forming into various parts. After U-shape bending, the specimen was loaded using a bolt. The proposed evaluation method is based on the measurement of critical hydrogen content or critical hydrogen charging condition for hydrogen embrittlement fracture at given stress and strain conditions. The hydrogen charging current density was increased in step-wise manner until cracking was observed, and cracking was detected by optical observation and by monitoring voltage between the sample and a counter electrode. The critical hydrogen contents for specimens with varied applied stress were obtained by means of thermal desorption spectroscopy. For the critical hydrogen content, both the hydrogen contents in strained portion of the specimen and no-strained portion were measured. The former is affected by introduced dislocations caused by straining and the latter is thought to be proportional to the hydrogen fugacity. Both critical hydrogen contents tended to be decreased slightly when the applied stress was relatively high.

提出了一种评价高强度钢板氢脆性能的方法。除了施加/残余应力和可扩散氢的影响外，除了考虑塑性应变的影响外，还采用了U型弯曲试样，因为汽车钢板通常在冲压成各种零件后使用。U形弯曲后，使用螺栓加载样品。所提出的评估方法是基于在给定的应力和应变条件下测量氢脆断裂的临界氢含量或临界氢填充条件。氢充电电流密度逐步增加，直到观察到破裂为止。并通过光学观察和监测样品与对电极之间的电压来检测裂纹。通过热脱附光谱法获得了具有变化的施加应力的样品的临界氢含量。对于临界氢含量，测量样品的应变部分和非应变部分中的氢含量。前者受应变引起的位错的影响，而后者则被认为与氢逸度成正比。当施加的应力较高时，两种临界氢含量都倾向于略有降低。测量样品的应变部分和非应变部分中的氢含量。前者受应变引起的引入位错的影响，而后者则被认为与氢逸度成正比。当施加的应力较高时，两种临界氢含量都倾向于略有降低。测量样品的应变部分和非应变部分中的氢含量。前者受应变引起的位错的影响，而后者则被认为与氢逸度成正比。当施加的应力较高时，两种临界氢含量都倾向于略有降低。