共查询到18条相似文献,搜索用时 93 毫秒
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采用氢渗透测试、慢拉伸试验等研究手段,探究EH36钢表面、1/4和1/2厚度处的氢陷阱、氢扩散系数及氢脆敏感性。结果表明,表面及1/4厚度处的显微组织主要为贝氏体,表面处的显微组织较为细小,1/2厚度处主要为铁素体和珠光体。可逆和不可逆氢陷阱密度由表面到1/2厚度处依次降低,氢扩散系数随之依次增大。随充氢电流密度或时间的增加,各厚度处拉伸试样的屈服强度、抗拉强度、伸长率均有不同程度的降低,氢脆敏感性随之增大;拉伸断口形貌由呈韧性断裂特征的韧窝状逐渐向呈脆性断裂特征的河流状花样转变。表面处的氢脆敏感性最小,1/2厚度处的氢脆敏感性最大;在1/2厚度处的拉伸断口观察到了一些氢致裂纹。 相似文献
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采用激光焊接工艺,对油气工程用4 mm厚经1030 ℃×2 h固溶+780 ℃×8 h时效和1030 ℃×2 h固溶+780 ℃×16 h时效两种热处理后的Inconel 718合金进行激光焊接,结合微观组织分析、拉伸性能分析和断口形貌分析,对合金母材及激光焊接头在原位充氢条件下的氢脆行为进行了研究。结果表明:长时间时效导致δ相大量析出,使合金母材的氢脆敏感性指数从正常时效态的0.27提高到过时效态的0.48。激光焊接头整体的氢脆敏感性没有受焊前热处理的影响,分别为0.39和0.38;由于焊缝内Laves相的析出,导致激光焊接头的氢脆敏感性高于正常时效态的母材。 相似文献
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目的研究X80管线钢在我国典型酸性环境(鹰潭土壤模拟溶液)下的氢致开裂行为。方法采用电化学动电位扫描技术、慢应变速率拉伸实验和扫描电镜技术,分析氢在X80管线钢中的渗透行为、材料的放氢行为、电化学充氢对材料拉伸性能的影响以及材料断口的形貌。结果通过氢渗透实验测得,在室温下,氢在X80管线钢中的的氢扩散通量J∞=7.31×10-11mol/(cm2·s),有效扩散系数Deff=5.36×10-8cm2/s,可扩散氢浓度C0=7.64×10-5mol/cm3。钢中的氧化铝类非金属夹杂及表面点蚀坑促进了氢致裂纹的萌生,充氢后试样发生穿晶断裂。随着充氢时间的增加,断口由韧性断裂转变为脆性断裂,氢致开裂敏感性增高。结论 X80管线钢在我国典型酸性环境下(鹰潭土壤模拟溶液)具有较高的氢致开裂敏感性。 相似文献
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用拉伸的方法研究了静态充氢和动态充氢对SM490B纯净钢力学性能的作用,结果表明:随着充氢电流密度的增加,试样的延伸率连续降低。动态充氢试样的氢致塑性损失明显大于静态充氢拉伸试样的氢致塑性损失。氢原子提高了试样的屈服强度,而试样的抗拉强度随电流密度增大而减小。随着充氢电流密度的增加,静态拉伸试样的断口均为韧窝状,而动态拉伸试样的断口形貌由韧窝状向准解理状变化。 相似文献
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采用阴极充氢和真空拉伸方法,研究了硼含量对氢原子在有序态Ni_3Fe合金中扩散的影响。结果表明,当合金中硼含量C_B≤0.06%(质量分数)时,氢原子在有序态Ni_3Fe合金中的扩散系数随C_B的增加而逐渐降低,而扩散激活能逐渐增大。当C_B0.06%后,氢原子的扩散系数随C_B的增加而变化很小,而扩散激活能略有减小。原子探针层析方法证实了硼原子在有序态Ni_3Fe合金中晶界处发生偏聚。对比研究硼含量对有序态Ni_3Fe合金中氢扩散系数及对合金在氢气环境中氢脆因子的作用,确认硼原子降低有序态Ni_3Fe合金在氢气环境中的氢脆敏感性的机理,是硼原子降低了氢原子在合金中的沿晶扩散系数。 相似文献
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Notched tensile tests were conducted under a slow displacement rate to evaluate the influences of grain size and aging on hydrogen embrittlement (HE) of T-200 maraging steel. In addition, an electrochemical permeation method was employed to measure the effective diffusivity (Deff) and apparent solubility (Capp) for hydrogen of various heat-treated specimens. The results indicated that the aged (482 °C/4 h) specimens comprised of numerous precipitates led to a raised Capp and a decreased hydrogen diffusivity as compared to those of the solution-treated ones. The solution-treated specimens were resistant to gaseous HE, whereas aged specimens were susceptible to it, implying the strength level was the controlling factor to affect the HE susceptibility of the specimens. Nevertheless, all specimens suffered from sulfide stress corrosion cracking (SSCC) severely but to different degrees. The aged specimens were more likely to form intergranular (IG) fractures in H2S but quasi-cleavage (QC) in H2. For the solution-treated specimens, a fine-grained structure was susceptible to HE in H2S and revealed mainly QC that differed from the IG fracture of the coarse-grained one. The fracture mode of the specimens could also be related to the transport path and / or the supply of hydrogen to the plastic zone of notched specimens in hydrogen-containing environments. 相似文献
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回火马氏体钢中氢的扩散行为及其氢脆敏感性 总被引:1,自引:0,他引:1
通过TDS方法研究了氢在18Cr2Ni4W和25CrNi2MoVNb两种低温回火马氏体钢中的扩散行为,同时结合慢应变速率拉伸实验研究了这两种马氏体钢的氢脆敏感性。结果表明,与18Cr2Ni4W钢相比,25CrNi2MoVNb钢因碳含量较高和晶粒显著细化作用使抗拉强度从1300 MPa级提高到了1500 MPa级后,其氢脆敏感性也明显增加。通过试样充氢后放置试验,测定氢在25CrNi2MoVNb钢和18Cr2Ni4WA钢中的扩散系数分别为7.87×10-7 cm2/s和3.99×10-7 cm2/s。可见,氢在25CrNi2MoVNb钢中更容易扩散,因而在充入相同可扩散氢时,25CrNi2MoVNb钢性能损失更大。 相似文献
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采用氢渗透试验和动态充氢拉伸试验研究了920℃冰水淬火后回火温度(560、600和640℃)对某含0.15%V和0.05%Nb(质量分数)高强度低合金钢的氢扩散系数和氢脆敏感性的影响,并利用金相显微镜、X射线衍射仪、透射电镜(TEM)观察分析回火试样的微观组织。结果表明,随回火温度升高,氢扩散系数增加,氢扩散激活能降低,同时钢的氢脆敏感性也降低,这是因为随回火温度升高,钢中作为氢陷阱的位错密度减少,从而使得氢陷阱密度减小,在相同的充氢条件下可扩散氢含量减小。 相似文献
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This article describes the effect of δ phase on the hydrogen embrittlement (HE) sensitivity of Inconel 718 conducted by notch tensile tests. Notch tensile specimens were subjected to proper heat treatment to produce various precipitation morphologies of δ phase. Hydrogen was charged into the tensile specimens before tensile tests via a cathodic charging process. The loss of notch tensile strength (NTS) due to hydrogen charging has been used as a criterion to evaluate the hydrogen embrittlement sensitivity. The study suggests that δ phase has deleterious effect on NTS. Fracture origins of hydrogen-charged specimens locate near the notch surfaces. The loss of NTS caused by hydrogen charging can be greatly decreased by dissolving δ. δ-free Inconel 718 has been proposed for applications in hydrogen environments. 相似文献
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The effect of various experimental conditions (i.e., hydrogen charging current density, charging time, solution concentration, and temperature) on the embrittlement and cracking susceptibility of 2205 duplex stainless steel was studied by electrochemical hydrogen charging and slow strain rate tests. The results showed that the choice of the experimental conditions had obvious effect on the hydrogen concentration in the specimens. A relationship between the embrittlement and hydrogen charging conditions was established by the investigation of the fracture morphology. Under the free‐charging condition, the fracture surfaces were characteristic of dimples, while on the condition of the dynamic hydrogen charging, the hydrogen‐induced fracture showed the appearance of cleavage. Further examination of fracture cracks confirmed that the ferrite phase acts as a preferential path for crack propagation. 相似文献
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采用慢应变速率试验和缺口试样拉伸试验,并结合断口分析,研究了X80钢在含氢煤制气环境中的氢脆敏感性。结果表明:高压含氢环境中X80钢的强度和塑性指标均有所下降,断口出现脆断形貌,表现出一定的氢脆敏感性,且横向取样方向对氢脆更为敏感;通过对比分析X80钢在高压氢气环境中慢拉伸和缺口拉伸两种状态下的韧性损失,发现缺口试样的三向应力集中区域受氢脆影响更为严重。 相似文献