试样条件对不锈钢堆焊层剥离的影响

通过一系列电解充氢试验研究了堆焊层剥离的影响因素，并采用有限元分析方法计算了堆焊结构中氢浓度的分布．比较了不同试作条件对试验结果的影响．结果显示，一定的母材厚度和焊后热处理条件，使熔合线附近氢浓度峰值提高，从而使氢剥离倾向增大．文中对试块近溶合线区的显微组织进行了研究．结果表明，提高焊后热处理参数，熔合线堆焊层侧增碳层宽度增加，氢致剥离的倾向增大．     

管线钢在含氢气的煤制天然气中服役安全性评估

煤制天然气是我国煤炭清洁利用的重要发展方向.现有管道用于输送煤制天然气(最高氢分压为0．72 MPa)时需要考虑其中低压氢气的影响,因而需先进行氢致开裂安全性评估.本文利用高压釜环境下恒载荷实验和电化学充氢,模拟研究X-70管线钢和20#钢在不同氢含量下的氢损伤和氢致延迟开裂,并对其在煤制天然气中服役安全性进行评估.在总压12 MPa (10 MPa N2+2 MPa H2)的高压釜中放置一个月,两种钢的金相试样均不出现氢损伤,U弯试样不开裂,加屈服强度σs的恒载荷试样不发生断裂.在含0．72 MPa的煤制天然气中长期服役时,进入两种钢的氢含量均远低于σs下发生氢致延迟开裂的门槛氢含量和出现氢损伤的门槛氢含量,因而X-70钢和20#钢在煤制天然气中长期服役均具有高的氢损伤和氢致开裂安全系数.     

稳态奥氏体合金的氢致软化

本文通过拉伸、室温蠕变及透射电镜观察，研究了稳态奥氏体合金的氢致软化现 象。确认稳态奥氏体合金中存在氢致软化，充氢改变位错组态和氢的运动是产生氢致软 化的原因之一。     

电流型氢渗透传感器研究

利用Devanathan-Stachurski电解池原理制造恒电解式与电池式电流型氢渗透传感器,用于监测氢在钢中的扩散速率及浓度.研究了镀镍时间、密封电解液对渗氢电流的影响,试验了以羟基氧化镍粉末作为阴极材料的电池型氢渗透传感器.实验结果表明:钢件表面镀镍5 min作为原子氢催化氧化的集氢面,经约5 h氧化后可以消除电镀渗氢的影响,使背景电流降至0.5 μA/cm~2以下;由聚乙烯醇和羧甲基纤维素钠按质量比4∶1混合,再与0.2 mol/L KOH溶液配制成非流动性的电解液作为密封胶,用于传感器内部电解液与工件镀镍面之间的密封,与单电解液的测量结果一致;在相同充氢条件下,恒电解式与电池式电流型氢渗透传感器测得的氢渗透曲线结果一致,与施加氧化电势的方式无关.     

氢在钢中扩散过程的研究

本文主要探论了氢在钢中的扩散过程.试验结果表明,氢的扩散过程仍服从Fick扩散第二定律.通过阴极电解充氢法,根据试验结果和理论计算,求出了氢在20号钢、20Cr钢和15MnVN钢中的最大平均溶解度和扩散系数.从而,为查明氢致裂纹的机理问题,提供了有用的分析数据.     

氢致7175铝合金韧脆断裂转变行为

采用阴极渗氢和低应变速率拉伸等试验，研究了氢对不同时效状态７１７５铝合金力学性能的影响．结果表明，屈服应力、断裂强度及延伸率等均随充氢时间的延长而下降；且在相同充氢时间条件下，下降程度随时效时间的增加而减小     

钢中氢致裂纹机构研究

用抛光的恒位移试样对处理到不同强度(σ_b=92～185公斤/毫米~2)的4种低合金钢在各种致氢环境(如电解充氢、纯氢、气体H_2S、水介质、H_2S水溶液、缓蚀剂水溶液、丙酮、酒精等有机溶液)下跟踪观察了氢致裂纹的产生和扩展过程。与此同时也测量了各种致氢环境(电解充氢、H_2S水溶液、水溶液、水中阴极化和阴极极化)下的K_(ISCC)(或K_(IH))和da/dt。并研究了它们随强度变化的规律。 结果表明,当加载裂纹前端的K_I>K_(ISCC)(K_(IH))后,在上面所说的任何一种致氢环境下都能产生氢致滞后塑性变形,并由此导致裂纹的产生和扩展。即随着氢的扩散进入,原裂纹前端塑性区及其变形量逐渐增大。对超高强钢,在滞后塑性区端点形成不连续的氢致裂纹,它们随滞后塑性变形的发展逐渐长大以致互相连接。当强度降低时,氢致裂纹沿滞后塑性区边界连续地向前扩展。这就表明,在Ⅰ型裂纹条件下,“氢脆”是氢致滞后塑性变形的必然结果。 在所有致氢环境下,止裂K_(ISCC)(K_(IH))均随钢的强度下降而升高。强度相同时,水中加缓蚀剂和阳极极化使K_(ISCC)升高,阴极极化使K_(ISCC)下降,,da/dt升高,而在H_2S饱和溶液以及加载电解充氢时K_(ISCC)(K_(IH))最低,da/dt最高。 实验也表明,在电解充氢条件下还能以另一种机构形成裂纹。它们的产生和     

不锈钢堆焊试件熔合区充氢前后的断裂韧性研究

研究了氢对不锈钢堆焊层熔合区的断裂韧性的影响作用。发现不锈钢堆焊层熔合区的断裂韧性随着充氢时间的增加而下降,结果表明,氢是引起加氢反应器不锈钢堆焊层剥离的主要因素。     

2-1/4Cr-1Mo钢抗氢脆性能的研究

用电解充氢方法研究了加氢反应器用2—1／4Cr-1Mo钢的氢脆。为研究该材料抗氢脆的性能,试样中的氢浓度约6．22μg／g,比反应器的实际操作工况更恶劣。结果表明该材料的抗氢脆性能较好,经脱氢处理后其韧性得以恢复。     

氢致奥氏体不锈钢晶格畸变

对３０４Ｌ和３１６Ｌ奥氏体不锈钢试样在充氢后和充氢同时进行Ｘ射线衍射分析，观察到在充氢过程中存在奥氏体晶格膨胀－收缩－膨胀的现象；在充氢后时效一段时间的情况下，存在奥氏体晶格收缩－膨胀－收缩的现象，并初步讨论了可能的原因。     

Effect of hydrogen on the friction and wear of Ni-P coatings

The effects of charging and outgassing on the friction and wear of Ni-P amorphous and nanocrystalline coatings were studied under ambient humidity and temperature. The results indicate that hydrogen charging can greatly decrease the volume loss during friction and increase the wear durability. However, the wear durability can be restored after outgassing. There are many cracks on the brittle nanocrystalline before charging, and no crack appears after charging, but there are only a few cracks on the outgassed sample. This indicates that hydrogen charging can inhibit the crack formation during friction for the brittle Ni-P nanocrystalline. For the charged sample, after the surface layer was removed by polishing, the wear track and the friction coefficient are consistent with those of an uncharged sample. The friction coefficient of the charged amorphous coating is very small within the first 140 s and then increases suddenly to the value corresponding to the uncharged sample. The absorbed surface layer lubricates the surface, reduces the friction coefficient, and improves the wear durability.     

Effect of shot peening on hydrogen embrittlement of high strength steel

The effect of shot peening (SP) on hydrogen embrittlement of high strength steel was investigated by electrochemical hydrogen charging, slow strain rate tensile tests, and hydrogen permeation tests. Microstructure observation, microhardness, and X-ray diffraction residual stress studies were also conducted on the steel. The results show that the shot peening specimens exhibit a higher resistance to hydrogen embrittlement in comparison with the no shot peening (NSP) specimens under the same hydrogen-charging current density. In addition, SP treatment sharply decreases the apparent hydrogen diffusivity and increases the subsurface hydrogen concentration. These findings are attributed to the changes in microstructure and compressive residual stress in the surface layer by SP. Scanning electron microscope fractographs reveal that the fracture surface of the NSP specimen exhibits the intergranular and quasi-cleavage mixed fracture modes, whereas the SP specimen shows only the quasi-cleavage fractures under the same hydrogen charging conditions, implying that the SP treatment delays the onset of intergranular fracture.     

涉氢环境中连续/间断腐蚀对X80钢力学性能的影响

This study investigated the susceptibility of X80 pipeline steel to hydrogen embrittlement given different hydrogen pre-charging times and hydrogen charging–releasing–recharging cycles in H₂S environment. The fracture strain of the steel samples decreased with increasing hydrogen pre-charging time; this steel degradation could almost be recovered after diffusible hydrogen was removed when the hydrogen pre-charging time was<8 d. However, unrecoverable degeneration occurred when the hydrogen pre-charging time extended to 16–30 d. Moreover, nanovoid formation meant that the hydrogen damage to the steel under intermittent hydrogen pre-charging–releasing–recharging conditions was more serious than that under continuous hydrogen pre-charging conditions. This study illustrated that the mechanical degradation of steel is inevitable in an H₂S environment even if diffusible hydrogen is removed or visible hydrogen-induced cracking is neglected. Furthermore, the steel samples showed premature fractures and exhibited a hydrogen fatigue effect because the repeated entry and release of diffusible hydrogen promoted the formation of vacancies that aggregated into nanovoids. Our results provide valuable information on the mechanical degradation of steel in an H₂S environment, regarding the change rules of steel mechanical properties under different hydrogen pre-charging times and hydrogen charging–releasing–recharging cycles.     

基于WBS-RBS-BN的蓄电池充电区域氢气火灾爆炸事故研究

通过现场测试,明确了蓄电池充电区域氢气浓度分布规律.通过WBS-RBS分析方法,得出蓄电池充电区域氢气火灾爆炸事故风险事件耦合矩阵,以此为依据得到氢气火灾爆炸事故故障树,将故障树转化为贝叶斯网络,使用GeNIe软件计算蓄电池充电区域氢气爆炸事故发生概率为2.688e-4.通过贝叶斯网络双向推导功能,计算氢气火灾爆炸事故发生条件下基本事件的后验概率,从而分析出导致事故发生的安全技术或管理的薄弱环节为人体静电、操作工人抽烟、金属部件碰撞、蓄电池过充、蓄电池破裂和机械排风装置故障,并提出了相应的对策措施,降低了蓄电池充电区域发生氢气火灾爆炸事故的风险.     

对苯二甲酸的加氢精制过程Ⅱ.不同粒度催化剂上4-CBA表观加氢动力学

对Pd/AC催化剂上对苯二甲酸(TA)加氢精制过程中的对羧基苯甲醛(4-CBA)加氢反应进行了研究。考察了氢分压、反应温度、催化剂颗粒大小对4-CBA消逝速率的影响,结果表明:在高于0.35 M Pa时,氢分压对4-CBA加氢反应速率的影响很小,而温度和催化剂粒度大小对加氢反应的影响显著。同时,工业条件下的TA加氢精制过程存在着严重的内外扩散。采用幂函数动力学模型方程利用M atlab拟合得到了不同粒度催化剂上的表观动力学方程。     

Hydrogen-induced cracking behaviors of Incoloy alloy 825

The effect of hydrogen on the fracture behaviors of Incoloy alloy 825 was investigated by means of slow strain rate testing (SSRT). Hydrogen was introduced into the sample by electrochemical charging. The results show that surface microcracks form gradually during aging at room temperature when desorption of hydrogen takes place after hydrogen charging at a current density of 5 mA/cm2 for 24 h. SSRT shows that the increase of ductility loss is significantly obvious as the hydrogen charging current density increases. Scanning electron microscopy (SEM) images reveal ductile fracture in the pre-charged sample with low current densities, while the fracture includes small quasi-cleavage regions and tends to be brittle fracture as the hydrogen charging current density increases to 5 mA/cm2.     

Hydrogen induced cracking of X80 pipeline steel

The hydrogen-induced cracking (HIC) behavior of X80 pipeline steel was studied by means of electrochemical charging, hydrogen permeation tests, tension test, and scanning electron microscopy (SEM). The experimental results indicate that the increase of charging time and charging current density or the decrease of the solution pH value leads to an increase of the hydrogen content in X80 steel, which plays a key role in the initiation and propagation of HIC. It is found that the majority of macro-inclusions within the as-used X80 steel do not constitute a direct threat to HIC except aluminum oxides, which directly or indirectly lead to HIC. The hydrogen trap density at room temperature is estimated to be pretty high, and this is an essential reason why the steel is sensitive to HIC. After hydrogen charging, the elongation loss rate and area reduction of X80 steel decline obviously, taking a noticeable sign of hydrogen-induced plasticity damages. It is demonstrated that the losses of these plastic parameters have a linear relation to the fracture size due to hydrogen.     

氢在金属玻璃Fe_(39)Ni_(39)Si_8B_(12)Mn_2中的扩散及其对弹性模量的影响

用排水集气法分别测量了淬态和退火处理Fe_(39)Ni_(39)Si_8B_(12)Mn_2金属玻璃在室温附近不同温度下的氢的扩散系数,由此计算出扩散激活能。退火处理导致的结构弛豫均使频率因子D_0和激活能变小。测量了样品在弯曲振动模式下共振频率,发现氢可以降低金属玻璃的杨氏模量,且充氢后时效过程中共振频率随时间的变化规律和时效过程中样品含氢量的曲线相似,即由氢降低的杨氏模量和含氢量成正比。