Study on hydrogen embrittlement resistance of vanadium molybdenum microalloyed 32MnB5 hot formed steel
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摘要: 在实验室条件下通过在传统32MnB5热成形钢基础上添加不同含量的V和Mo，利用慢应变速率拉伸试验来评价材料的氢脆敏感性，并结合氢渗透试验对微合金化热成形钢的抗氢脆性能变化机理进行了探讨。试验结果表明：添加V和Mo合金元素均有利于提高材料的抗氢脆性能，材料充氢后的塑性损失均出现降低。其中V与Mo复合添加相对于单一添加V样品，其原奥氏体晶粒尺寸及纳米级析出相尺寸更为细小，可以有效捕获氢原子，阻碍了氢原子的扩散，因此表现出最佳的抗氢脆性能，氢扩散系数降至7.3×10−11 m2/s，可扩散氢浓度减少至4100 mol/m3。Abstract: Different contents of vanadium and molybdenum were added into the traditional 32MnB5 hot formed steel under laboratory conditions, the hydrogen embrittlement sensitivity of the microalloyed material was evaluated by slow strain rate tensile test, and the change mechanism of hydrogen embrittlement resistance of microalloyed hot formed steel was discussed combined with results from hydrogen penetration test. It is found out that addition of V and Mo alloy elements is conducive to improve the hydrogen embrittlement resistance of the material, and the plastic loss of the material after hydrogen charging is reduced. Compared with the V-added only sample, the original austenite grain size and nano precipitate size of V-Mo combinated addition are smaller, which can effectively capture hydrogen atoms and hinder the diffusion of hydrogen atoms. Therefore, the V-Mo steel shows the best resistance to hydrogen embrittlement, and the hydrogen diffusion coefficient is reduced to 7.3×10−11 m2/s, the diffusible hydrogen concentration is reduced to 4100 mol/m3.
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Key words:
- hot formed steel /
- 32MnB5 /
- microalloying /
- vanadium /
- molybdenum /
- hydrogen embrittlement
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图 1 各试样的显微组织观察及定量统计
Figure 1. Observation and quantitative statistics of microstructure in each sample
图 2 各试样的析出相微观形貌及尺寸占比
（a）1#；(b)2#；（c）3#；（d）占比
Figure 2. Microstructure and size proportion of precipitates in each sample
图 3 各试样在不同充氢条件下的应力-应变曲线（a）、（b）、（c）及延伸率损失量（d）
Figure 3. Stress-strain curves and elongation loss of each sample under different hydrogen charging conditions
图 4 1#试样在3 mA/cm2电流密度下的拉伸断口形貌
Figure 4. Tensile fracture morphology of 1# sample under 3 mA / cm2 current density hydrogen charging condition
图 5 2#试样在3 mA/cm2电流密度下的拉伸断口形貌
Figure 5. Tensile fracture morphology of 2# sample under 3 mA / cm2 current density hydrogen charging condition
图 6 3#试样在3 mA/cm2电流密度下的拉伸断口形貌
Figure 6. Tensile fracture morphology of 3# sample under 3 mA / cm2 current density hydrogen charging condition
图 7 各试样的氢渗透曲线（a）、（b）及氢扩散系数及可扩散氢浓度（c）
Figure 7. Hydrogen permeability curve (a）, （b) Deff and C0 R (c) of each sample
表 1 热成形钢的主要化学成分
Table 1. Chemical compositions of the three hot-stamping steels used in this study
% C Si Al Mn Cr Ti Mo V 1# 0.32 0.25 0.04 1.2 0.12 0.03 2# 0.32 0.25 0.04 1.2 0.12 0.03 0.05 3# 0.32 0.25 0.04 1.2 0.12 0.03 0.1 0.05 
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