钛在海水中的阴极极化行为

用电化学动态极化法和SEM、XRD等研究了钛在海水中的阴极极化行为。结果表明 :钛在海水中的阴极极化明显 ,析氢受到阻滞。温度升高 ,利于氢在钛上析出。钛在海水中阴极极化对氢脆十分敏感 ,在 - 1.1V恒电位阴极充氢4 8h的钛试样中没有发现TiHx相 ,但其断裂面已出现了明显增多的解理舌和解理台阶     

真空渗碳处理38CrMoAl渗氮钢的微观组织及氢脆敏感性分析

为了满足汽车轻量化对材料性能的要求,选择齿轮用38CrMoAl渗氮钢作为测试材料,以电化学充氢方法与慢应变拉伸相结合的方式测试了真空渗碳(Vacuum Carburizing,VC)试样的氢脆敏感性,同时与淬火+低温回火态(Quenching+ Low-Tempering,QL)处理试样进行了比较.研究结果表明:QL试样中形成了均匀形态的低碳回火马氏体;VC试样渗碳层中以高碳回火马氏体为主,存在少量的残余奥氏体.VC试样在表面部位的最大硬度达到了732 HV;QL试样在450 HV附近.对QL试样进行充氢后表现出了与初始试样接近的拉伸强度,而断后伸长率显著减小,计算相对断后伸长率差异得到QL试样氢脆敏感性指数(HEI)为54.3％.对38CrMoAl渗氮钢进行渗碳处理后会引起其氢脆敏感性的快速提高.对QL试样充氢处理后试样产生了更明显的脆性断裂,表现出了与高强度马氏体钢氢致断裂相近的特性;充氢后VC试样在断裂后形成了许多韧窝状的结构,呈现韧性断裂的特性.     

钛材在海水中的阴极极化行为

用电化学动态极化法和SEM、XRD等研究了钛在海水中的阴极极化行为。结果表明：钛在海水中的阴极极化明显，析氢受到阻滞。温度升高，利于氢在钛上析出。钛在海水中阴极极化对氢脆十分敏感，在－1．1V恒电位阴极充氢48h的钛试样中没有发现TiHx相，但其断裂面已出现了明显增多的解理舌和解理台阶。     

铜离子及电位对5083铝合金阴极保护行为的影响

目前有关船体防污涂料中的铜离子及阴极保护电位对铝合金船体的腐蚀电化学研究不够深入。通过极化试验、电化学阻抗谱(EIS)测试及外加恒电位阴极保护试验,并结合腐蚀形貌观察,研究了5083铝合金在有无Cu~(2+)的3.5%NaCl溶液中的极化及腐蚀特性,并结合不同电位下的阴极保护行为,探讨了其阴极保护电位范围。结果表明:防污剂中的Cu~(2+)沉积在铝合金基体表面会造成防腐蚀性能下降,降低铝合金舰船的阴极保护效果,应该避免Cu~(2+)的渗入;阴极保护电位过正,保护效果不佳,会造成铝合金表面发生点蚀,但若阴极保护电位过负,表面会发生析氢腐蚀,因此其合理的阴极保护电位范围为-1.00~-1.10 V(vs SCE)。     

几种结构钢在人造海水中自腐蚀电位和析氢电位的研究

本文介绍了16Mn钢和2 1/4Cr-1Mo钢[注1]在人造海水中的自腐蚀电位和析氢电位的测量原理和方法。在实验中用怛电位仪测量不同试样的自腐蚀电位和析氢电位;研究了温度对试样自腐蚀电位的影响;不同热处理方法对试样自腐蚀电位和析氢电位的影响。     

海水中极化电位对X70钢氢脆敏感性的影响

为探索X70钢最大阴极保护电位,采用电化学测试和慢应变速率实验（SSRT）并结合断口扫描电镜观察,研究了低温低溶解氧和常温海水中阴极极化电位对X70钢氢脆敏感性的影响.结果表明：相对常温海水,X70钢在低温低溶解氧海水中的析氢电位正移;随阴极极化电位的负移,X70钢的最大抗拉强度、屈服强度增加且氢脆敏感性增加;在低温低...     

低驱动电位铝合金牺牲阳极的研制

针对传统牺牲阳极由于电位过负导致高强钢氢脆敏感性增加的问题,以Ga为主要活化元素,加入Zn和Si改善阳极的溶解性能,研制了具有良好电化学性能的低驱动电位铝合金牺牲阳极材料,并验证了其对高强钢的保护效果,评价了其对高强钢氢脆敏感性的影响。     

A7N01S-T5铝合金在84消毒液中的电化学行为

为了研究消毒液对高铁车厢铝合金腐蚀的影响,采用动电位极化和电化学阻抗2种电化学测量技术,研究了高铁车体A7N01S-T5铝合金在不同浓度(100,200,400,800,1 000 mg/L) 84消毒液中的电化学行为,取自来水作为对照试验,使用VHX-2000C超景深三维体式显微镜观察试验后铝合金电极的微观形貌。结果表明:电化学阻抗谱中的Nyquist谱电极过程受活化和扩散控制,随着消毒液浓度升高电荷转移电阻和低频阻抗值减小并趋于一致;极化曲线的阴极过程和阳极过程分别以析氢反应和氧化还原反应为主,随着消毒液浓度升高,自腐蚀电位在不断负移后趋于一致,点蚀电位不断负移,腐蚀电流密度逐渐增大后趋于一致;随着消毒液浓度升高合金表面腐蚀由点蚀发展为全面腐蚀,腐蚀区域扩展缓慢,腐蚀速度减缓。     

AZ31B镁合金TIG焊接件应力腐蚀性能研究

为了研究AZ31B镁合金钨极氩弧焊接件应力腐蚀性能,室温下采用三点加载的方式,在去离子水中对试样进行应力腐蚀试验。利用光学显微镜(OM)观测试样微观结构,利用扫描电镜(SEM)观测应力腐蚀断口,利用X-350A型X射线应力仪和CHI660B型电化学工作站分别测定试样表面残余应力和动电位极化曲线。试验结果表明:采用单面焊双面成型工艺,在45～50A的焊接电流及合适的焊接速度条件下,焊接2.2mm厚AZ31B镁合金薄板时,钨极氩弧焊能够获得理想的焊接接头,抗拉强度达到209MPa;焊接件热影响区表面残余拉应力为60MPa;同母材相比,焊接件自腐蚀电位减小27mV,腐蚀电流增大了41.4%,从而增加焊接件腐蚀倾向;AZ31B焊接件在去离子水中浸没192h后出现应力腐蚀开裂,属于穿晶型脆性断裂,这表明AZ31B镁合金焊接件在去离子水中具有很高的应力腐蚀敏感性。     

海洋大气中SO2含量对16Mn钢腐蚀断裂及渗氢行为的影响

氢还原对钢材在大气腐蚀中的作用不可忽视,过去对其研究较少。采用电化学渗氢试验及慢应变速率拉伸方法研究了模拟海洋大气环境中SO2浓度对16Mn钢应力腐蚀断裂及氢渗透行为的影响。结果表明,随着SO2浓度的增大,试样断裂延伸率减小,断裂特征由塑性断裂逐渐转变为脆性断裂;随着SO2浓度的增大,氢渗透电流增大,SO2对氢渗透电流具有双重促进作用,第一个峰值的出现主要与SO2的酸性有关,第二个峰值的出现主要是由于酸的再生循环所致。     

Stress corrosion cracking and hydrogen embrittlement cracking of welded weathering steel and carbon steel in a simulated acid rain environment

Abstract

The stress corrosion cracking (SCC) and hydrogen embrittlement cracking (HEC) characteristics of welded weathering steel and carbon steel were investigated in aerated acid chloride solution. The electrochemical properties of welded steels were investigated by polarisation and galvanic corrosion tests. Neither weathering steel nor carbon steel showed passive behaviour in this acid chloride solution. The results indicated that weathering steel had better corrosion resistance than carbon steel. Galvanic corrosion between the weldment and the base metal was not observed in the case of weathering steel because the base metal was anodic to the weldment. However, the carbon steel was susceptible to galvanic corrosion because the weldment acts as an anode. Slow strain rate tests (SSRT) were conducted at a constant strain rate of 7.87 × 10⁷ s^-1 at corrosion potential, and at potentiostatically controlled anodic and cathodic potentials, to investigate the SCC and HEC properties in acid chloride solution. The welded weathering steel and carbon steel were susceptible to both anodic dissolution SCC and hydrogen evolution HEC. However, weathering steel showed less susceptibility of SCC and HEC than carbon steel at anodic potential because of Cr and Cu compounds in the rust layer, which retarded anodic dissolution, and at cathodic potential due to the presence of Cr, Cu, and Ni in alloy elements, which inhibit the reduction of hydrogen ions. SEM fractographs of both steels revealed a quasicleavage fracture in the embrittled region at applied anodic and cathodic potentials.     

Hydrogen embrittlement property of a 1700-MPa-class ultrahigh-strength tempered martensitic steel

The hydrogen embrittlement property of a prototype 1700-MPa-class ultrahigh-strength steel (NIMS17) containing hydrogen traps was evaluated using a slow strain rate test (SSRT) after cathodic hydrogen precharging, cyclic corrosion test (CCT) and atmospheric exposure. The hydrogen content in a fractured specimen was measured after SSRT by thermal desorption spectroscopy (TDS). The relationship between fracture stress and hydrogen content for the hydrogen-precharged specimens showed that the fracture stress of NIMS17 steel was higher, at a given hydrogen content, than that of conventional AISI 4135 steels with tensile strengths of 1300 and 1500 MPa. This suggests better resistance of NIMS17 steel to hydrogen embrittlement. However, hydrogen uptake to NIMS17 steel under CCT and atmospheric exposure decreased the fracture stress. This is because of the stronger hydrogen uptake to the steel containing hydrogen traps than to the AISI 4135 steels. Although NIMS17 steel has a higher strength level than AISI 4135 steel with a tensile strength of 1500 MPa, the decrease in fracture stress is similar between these steels.     

Hydrogen embrittlement property of a 1700-MPa-class ultrahigh-strength tempered martensitic steel

Abstract

The hydrogen embrittlement property of a prototype 1700-MPa-class ultrahigh-strength steel (NIMS17) containing hydrogen traps was evaluated using a slow strain rate test (SSRT) after cathodic hydrogen precharging, cyclic corrosion test (CCT) and atmospheric exposure. The hydrogen content in a fractured specimen was measured after SSRT by thermal desorption spectroscopy (TDS). The relationship between fracture stress and hydrogen content for the hydrogen-precharged specimens showed that the fracture stress of NIMS17 steel was higher, at a given hydrogen content, than that of conventional AISI 4135 steels with tensile strengths of 1300 and 1500 MPa. This suggests better resistance of NIMS17 steel to hydrogen embrittlement. However, hydrogen uptake to NIMS17 steel under CCT and atmospheric exposure decreased the fracture stress. This is because of the stronger hydrogen uptake to the steel containing hydrogen traps than to the AISI 4135 steels. Although NIMS17 steel has a higher strength level than AISI 4135 steel with a tensile strength of 1500 MPa, the decrease in fracture stress is similar between these steels.     

Fracture Mechanism of UNS G10190 Steel in Hydrochloric Acid Containing Ferric Ion

In the paper, a new kind of electrochemical sensor was used for measuring the permeation rate of atomic hydrogen (H permeation current I) through the sensor in 5% HCI solution containing ferric ion with different concentrations. The susceptibility of brittle fracture and the fracture mechanism of UNS G10190 steel in the solution were studied by slow strain rate tensile technique (SSRT), scanning electron microscope (SEM) and cathodic and anodic polarization. The embrittlement of the steel in the solution was expressed as index of embrittlement (F%). The results showed that the fracture mechanism of the steel in 5%HCl aqueous solution containing ferric ion would be changed from hydrogen induced cracking (HIC) to anodic dissolution in nature with the increase of the concentration of ferric ion in the solution.     

飞机表面水基清洗剂对金属材料腐蚀及氢脆性能影响研究

研究了AHC-1及AHC-5两种飞机表面水基清洗剂对飞机表面典型金属材料的腐蚀性能及高强度钢氢脆性能的影响,探讨了应用缓蚀剂控制高强度钢氢脆的有效性以及用电化学极化法预测高强度钢在清洗剂中的氢脆倾向性.     

Electrochemical corrosion and mechanical behaviors of the charged magnesium

The electrochemical corrosion and mechanical behaviors of the charged magnesium were investigated using Mott–Schottky (M–S) test and slow strain rate test (SSRT), respectively. The results showed that the hole carrier and vacancy concentrations in the corrosion film increased after cathodic charging due to the formation of magnesium hydroxide. The increasing vacancy concentration caused the increase of the permeation rate of hydrogen to the interior of matrix. When the inner stress caused by synergistic effect of hydrogen pressure and expansion stress of the formation of magnesium hydride was above the fracture strength, crack initiated and propagated. It indicated that hydrogen embrittlement (HE) mechanism for the stress cracking corrosion (SCC) of magnesium and its alloys. After cathodic charging, the corrosion resistance and mechanical properties of matrix deteriorated.     

Effect of cathodic potential on stress corrosion cracking behavior of different heat-affected zone microstructures of E690 steel in artificial seawater

In this work,the stress corrosion cracking(SCC)behavior of E690 steel base metal(BM)and different heat-affected zone(HAZ)microstructures,i.e.,coarse grain HAZ(CGHAZ),fine grain HAZ(FGHAZ),and intercritical HAZ(ICHAZ),was investigated at different cathodic potentials in artificial seawater by slow strain rate tensile tests,scanning electron microscopy and electron back-scattered diffraction measurements.The results show that the HAZ microstructures and BM exhibit different SCC susceptibilities:FGHAZ相似文献   

Measurement of hydrogen and embrittlement of high strength steels

Hydrogen embrittlement of high strength steel is believed to be one of the main reasons for the cracking of prestressed concrete structures. In this study, hydrogen was generated on the steel surface by applying different fixed cathodic potentials. The steel was immersed in simulated carbonated concrete solutions with and without 0.1 M NaCl. Simultaneously, the steel was subjected to tensile loading at slow strain rate until fracture. Fractographic analysis and the measurement of the concentration of absorbed hydrogen in the iron lattice were performed. Results showed that the hydrogen atom only penetrated into the iron lattice when the steel was loaded above its yield stress. This phenomenon produced quasi-cleavage like fracture, and the strain at fracture was considerably reduced. The presence of chloride ion together with the hydrogen embrittlement did not provoke a remarkable synergic effect in the mechanical properties of high-strength steel.     

THE EFFECT OF CATHODIC POLARIZATION ON CORROSION FATIGUE OF A HIGH STRENGTH STEEL IN SALT WATER

Abstract— Corrosion fatigue crack growth rates in high strength steel are often increased when a large cathodic polarization is applied. The corrosion fatigue mechanism in this case is generally considered to be due to hydrogen embrittlement. In the present study the crack growth process was carefully monitored by taking replicas from initially smooth specimens of a high strength steel under fully reversed push-pull loading while: (1) exposed to laboratory air, (2) immersed in a 0.6 M sodium chloride (NaCl) solution at open circuit potential (OCP) and (3) with an applied cathodic potential of —1250 mV (SCE). It is shown that the effect of cathodic polarization is dependent on the applied stress level and the nature of the cracking process, which in turn, is related to the sue of the crack. For stress levels at or below the in-air fatigue limit, failure did not occur for cathodically polarised specimens despite the number of loading cycles being 10 times that of the lifetime of identical tests in solution at the open circuit potential. At stress levels above the in-air fatigue limit the reduction in fatigue endurance caused by the presence of the corrosive environment can be partially recovered through cathodic polarization. The role of non-metallic inclusions in the cracking process under various exposure conditions is discussed, and a cracking mechanism is proposed.