异种高强钢气保焊焊接接头的氢脆敏感性

利用氢渗透试验、电化学测试、慢应变拉伸试验(SSRT)研究了异种高强钢气保焊焊接接头在海水中的氢渗透行为及应力腐蚀敏感性,并结合扫描电镜对断口形貌进行了观察。结果表明:异种钢焊接接头各区域的耐蚀性能和氢渗透特性存在明显差别,A侧热影响区的耐蚀性能最差并有明显的析氢倾向;充氢后焊接接头的腐蚀倾向和析氢倾向加剧,自腐蚀电位发生负移,析氢电位正移;不同阴极极化电位拉伸下,异种钢焊接接头的抗拉强度和规定塑性延伸强度都分别在830 MPa和760 MPa左右,介于基体A和基体B之间,断裂位置均在A侧热影响区,表明A侧热影响区是焊接接头产生氢脆断裂的危险区域,当阴极极化电位负于-950 mV时,焊接接头出现明显的氢脆特征。     

阴极保护电位对稠油输送管道氢脆敏感性影响的研究

采用慢应变速率拉伸(SSRT)实验,结合断口形貌分析,研究了在稠油输送模拟工况下不同阴极保护电位对Q235钢和L450钢氢脆敏感性的影响。结果表明,Q235钢的氢脆敏感性高于L450钢的。随着阴极保护电位负移,Q235钢和L450钢断口形貌逐渐由韧窝型韧性断裂向解理断裂转变,断面收缩率和断面收缩率损失系数增大,氢脆敏感性逐渐增加。在此工况条件下,Q235钢的最大保护电位应正于-1200 m V,L450钢最大保护电位应正于-1400 m V。     

温度及极化电位对10Ni5CrMo钢氢脆敏感性的影响

采用电化学阻抗谱测试、慢应变速率试验和断口形貌观察等研究了温度和极化电位对10Ni5CrMo钢在海水环境中氢脆敏感性的影响。结果表明:同一温度下,随极化电位负移,电荷转移电阻减小,断裂时间、断后伸长率和断面收缩率明显降低,氢脆系数(F)增加,材料的氢脆敏感性显著增加,且当极化电位达到-1 000mV(vs.SCE)时,氢脆系数已超过安全区允许的最高值25%,此时材料有可能发生氢脆;同一极化电位下,随温度增加,电荷转移电阻减小,断裂时间、断后伸长率、断面收缩率降低,氢脆系数增加,材料的氢脆敏感性增强;与极化电位相比,4～25℃条件下,温度对10Ni5CrMo钢的氢脆敏感性影响较小。     

阴极极化对907钢氢脆敏感性的影响

采用慢应变速率拉伸试验方法结合断口扫描电镜观察,研究了阴极极化对907钢在海水中氢脆敏感性的影响。结果表明随极化电位负移,907钢在海水中氢脆敏感性增加,极化电位为-1.06V(vs.SCE)时,拉伸试样出现脆性解理断裂特征,极化电位为-1.16V时,907钢主要为脆性断裂。     

阴极保护条件下X80钢在新疆农田土壤和模拟溶液中的氢脆敏感性差异研究

选择西部管道用大管径X80钢,通过外加阴极保护电位下的慢应变拉伸试验结合阴极极化曲线对比分析了其在新疆农田水饱和土壤及其模拟溶液中氢脆敏感性的变化规律。结果表明,随阴极保护电位的负移,X80钢的断面收缩率和延伸率逐渐降低,氢脆敏感性增加;农田土壤和模拟溶液中阴极保护电位分别达到-1.15V(CSE,下同)和-1.10V时,X80钢发生明显脆断;X80钢在模拟溶液中的氢脆敏感性高于在土壤中。因此利用土壤模拟溶液对X80钢进行氢脆敏感性研究更偏保守,是适宜的。     

pH值对海水中TMCP X80钢氢脆敏感性影响

采用氢渗透实验法、动电位极化法研究TMCP X80管线钢在不同pH值海水中的氢渗透行为,结合扫描电镜 (SEM) 观察研究显微组织及氢渗透行为对氢脆敏感性的影响。结果表明,随着海水pH值的减小,析氢电位发生正移。天然海水和酸性海水中氢扩散系数随着极化电位负移而增加;极化电流密度越大,氢扩散系数和氢浓度越大。在负于析氢电位时,显微形貌显示出明显的蚀坑和氢鼓泡,酸性海水中更严重。随着海水pH值的减小及外加阴极极化电位负移,氢扩散到材料内部的量更大;充氢电流密度增加也促进氢的扩散,X80钢氢脆敏感性增加。     

17-4PH不锈钢的析氢行为

采用电化学测试的方法评价了两种强度的17-4PH不锈钢在海水中的阴极极化行为;采用充氢试验研究了两种强度的17-4PH不锈钢在-1.1V(SCE,下同)电位下阴极极化15d后的含氢量;采用慢应变速率试验研究了两种强度17-4PH不锈钢在充氢后的氢脆系数。结果表明:两种强度的17-4PH不锈钢在海水中的析氢转变电位均在-0.90V左右;低强度不锈钢的氢质量分数约为2.55×10~(-4)%,而高强度不锈钢的氢质量分数则高达6.84×10~(-4)%;试样充氢后,高强度不锈钢的脆性明显增加,而低强度不锈钢的脆性增加不明显,高强度不锈钢的氢脆系数远超过25%,此时材料已存在氢脆危险,而低强度不锈钢的氢脆系数约为18%左右,尚处于氢脆安全区。     

阴极极化对不同时效状态7003铝合金应力腐蚀行为的影响

采用电化学腐蚀试验与不同阴极极化电位下的慢应变速率拉伸试验,并结合XRD衍射图谱分析及SEM断口形貌观察,研究了阴极极化对峰时效(PA),双峰时效(DPA)以及回归再时效(RRA)7003铝合金在3.5%Na Cl溶液中应力腐蚀类型的影响。结果表明,在开路电位下7003铝合金的应力腐蚀主要由阳极溶解控制,应力腐蚀敏感性ISCC(PA)ISCC(DPA)ISCC(RRA)。而外加阴极电位的情况下XRD衍射谱中出现Al H3衍射峰,断口形貌则表现出沿晶及解理倾向,说明应力腐蚀转变为由氢脆控制,且氢脆敏感性(IHE)随着极化电位的负移而不断增加,其中3种时效状态的敏感性顺序为:IHE(PA)IHE(DPA)IHE(RRA)。     

波型与电位对A537钢疲劳裂纹扩展的影响

研究了A537钢在3.5%NaCl水溶液中阴极极化与阳极极化条件下加载波型对疲劳裂纹扩展速率的影响并研究了相应电位条件下应变电极的电化学响应规律,结果表明,在外加电位为-800mV(SCE)以上时阳极溶解机制起主导作用,在-800mV以下时氢脆机制起主导作用,在阳极极化条件下,持续应变型加载波型的影响主要体现于低△K范围,而在阴极极化条件下,其影响体现于高△K范围,持续应变导致了自腐蚀电位的下降与阳极溶解电流密度的大幅度提高     

阴极充氢对1000 MPa级高强钢氢脆敏感性的影响

在海水环境中,采用电化学试验、氢渗透试验和慢应变速率试验(SSRT)以及结合SEM断口观察,研究了阴极充氢对1000 MPa级高强钢氢脆敏感性的影响。结果表明:阴极充氢电位对高强钢的氢渗透行为影响明显,随着阴极充氢电位的负移,氢的扩散系数波动不大,但饱和渗氢电流和氢溶解度逐渐增加,在阴极充氢电位为-1.05 V时,氢的溶解度为3.35 mol/m~3,为最大值。随着阴极充氢电位的负移,断口形貌逐渐由韧性断裂向解理脆性断裂转变,且断口边缘逐渐出现明显的解理裂纹。在阴极充氢电位为-0.91 V时,高强钢的氢脆系数约为25%,为最适宜的阴极保护电位。     

阴极极化对高强度船体结构钢焊缝氢脆敏感性的影响

在恒定阴极电位下利用慢应变速率拉伸试验研究高强度船体结构钢焊缝的电化学性能和力学性能。结果表明,试样拉伸断裂主要发生在焊缝的熔合区;结构钢的阴极极化程度对抗拉强度和屈服强度的影响不大;随阴极电位负移,船体结构钢在海水中的延伸率、断裂时间和断裂应变率逐渐减小, 并且当施加阴极电位为-0.89 V（vs SCE）时各项性能最佳。同时,随着阴极电位负移,断裂方式逐渐从韧性断裂向脆性断裂发展,氢脆敏感性逐渐增加,在 -0.70 V~-0.89 V（vs SCE）之间氢脆敏系数低于5%,不发生氢脆;当电位负于-0.94 V（vs SCE）,氢脆敏感性迅速提高,当极化电位为-0.99 V （vs SCE）时氢脆系数显著增大至20%,断口开始出现解理单元细小准解理断裂特征;在负于-1.04 V（vs SCE）时,氢脆系数已高于25%,进入危险区,且断口开始出现较多解理单元粗大的准解理、解理等氢脆断裂特征;随着电位继续负移至-1.14 V（vs SCE）,断口完全出现解理组织、沿晶、穿晶结构或者两者混合的氢脆断裂特征。     

Electrochemical study of hydrogen embrittlement and optimum cathodic protection potential of welded high strength Steel

Electrochemical properties and mechanical properties of welded high strength steel were investigated by the slow strain rate test (SSRT) method with an applied constant cathodic potential. There was no correlation between maximum tensile strength, yield strength, stress at failure, and hydrogen embrittlement. However, the elongation, time-to-fracture, and strain-to-failure ratio decreased with shifting potential of the negative direction. Elongation, time-to-fracture, and strain-to-failure ratio for the various welding methods displayed the highest values when the potential was −770 mV regardless of post-weld heat treatment (PWHT) conditions. The elongation, time-to-fracture, and amount of dimples by PWHT were increased. The optimum potential region for cathodic protection without hydrogen embrittlement was observed between −770 and (above) −850 mV (SCE) in the post-weld specimens heat treated at 550°C and the as-welded specimens.     

表面涂层对奥贝球铁水脆化行为的影响

水附着拉伸试验中,试样表面附着的水在试样塑性变形时分解出氢使奥贝球铁(ADI)产生氢脆,抗拉强度和伸长率显著下降,发生明显的水脆化现象.试样表面镀锡使ADI的抗拉强度和伸长率下降,镀锡层不能有效防止ADI的水脆化.聚乙烯涂覆能降低ADI的水脆化程度,而环氧树脂和尼龙涂覆无防止ADI水脆化的效果.     

Improvement of hydrogen embrittlement and stress corrosion cracking by annealing for Al-4.4Mg-0.6Mn alloy

With no annealing treatment, cathodic polarization trends in 5083F Al alloy revealed concentration polarization and activation polarization. However, the annealed specimens have lower current densities at corrosion protection potential compared to the non-annealed specimen. The results of SSRTs conducted in seawater at the applied potential range of ?1.8 V to ?0.5 V indicated that the maximum tensile strength, elongation, and time-to-fracture had high values at applied potentials of ?0.7 to ?1.4 V. The maximum tensile strength, elongation, and time-to-fracture decreased when the potential values were beyond this range in either anodic or cathodic direction. In general, the increased shear lip caused by annealing treatment indicates elongation. Time-to-fracture would likely increase with elongation. Potentials between ?0.5 V to ?0.6 V were found to be in the region of stress corrosion cracking. The corrosion protection zone was determined to be ?0.7 V to ?1.4 V because these potential ranges produced good mechanical properties. Potential less than ?1.4 V produced a fractured surface with a mixture of dimples (ductile fractures) and a quasi-cleavage pattern resulting from the effects of hydrogen gas.     

Hydrogen embrittlement properties of heat affected zone of high strength steel in shielded metal arc welding

Corrosion resistance, mechanical properties and hydrogen embrittlement were investigated from an electrochemical view, with the slow strain rate test (SSRT) method with applied constant cathodic potential. Fracture surface was analyzed by SEM. Corrosion resistance and mechanical properties were increased by post-weld heat treatment (PWHT) compared to those in the as-welded condition. Elongation and time-to-fracture were decreased with shifting cathodic polarization potential to the low potential direction. On analysis of SEM fractography, the quasi-cleavage (Q.C) fracture mode was also observed with an increase of susceptibility to hydrogen embrittlement. At the applied cathodic potential between −770 mV and −875 mV (SCE; saturated calomel electrode), the fracture morphology was of the dimple pattern with ductile fracture, while it changed to the transgranular pattern at under −900 mV (SCE). Eventually it is suggested that an optimum cathodic protection potential range was from −770 mV to −875 mV (SCE) without regard to PWHT condition.     

氢对铜的电化学行为和应力腐蚀的影响

纯铜充氢后并不改变组织结构和晶粒大小而且抗拉强度、伸长率和面缩率也不变化，这表明铜没有氢脆，在ＮａＮＯ＿２溶液中，氢使纯铜电位降低，使应力腐蚀开裂敏感性升高，但断口形貌不发生变化。     

回火温度对含V、Nb高强度低合金钢氢脆敏感性的影响

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。     

EFFECT OF TEXTURE ON HYDROGEN EMBRITTLEMENT SUSCEPTIBILITY OF STEEL

本文用阴极选择方向充氢法研究了261超纯铁素体不锈钢和300M低合金超高强度钢冷轧板材的织构与氢脆方向性的关系。用冲击试验衡量脆性,用倒极图法测定板材三个方向的织构,用扫描电镜观察表面和断口形貌。结果证实冷轧板材的氢脆有明显的方向性,平行轧向的方向,充氢敏感性最强;垂直轧向的方向,充氢敏感性最弱。 利用氢的位错短路通道扩散模型解释氢脆的方向性,得到了满意的结果。以的织构系数表示某方向上的位错线露头分布份数,则在位错密度相等条件下,〔P〕_E值与冲击值损失率成直线关系。因此取向集中在〈110〉,〈211〉和〈321〉方向的织构,氢脆更敏感。〔P〕_E值是氢脆控制因素之一。     

Effects of Prior Corrosion with and Without Stress on the Mechanical Properties of 7475-T761 Aluminum Alloy

The effect of prior corrosion on the mechanical properties of 7475-T761 aluminum alloy was investigated by immersion test, stress corrosion test, cathode charge method and electrochemical polarization test. Results show that prior corrosion in the solution with 3 wt% Na Cl and 0.5 wt% H2O2 leads to mechanical properties deterioration of 7475-T761 aluminum alloy. Moreover, the elongation decreases significantly. This is mainly attributed to electrochemical corrosion and hydrogen embrittlement, in which corrosion plays a major role. Tensile stress promotes the degradation of the mechanical properties by accelerating the pitting corrosion and hydrogen embrittlement.     

Effect of atomic ordering on environmental embrittlement of （Co,Fe）3V alloy in gaseous hydrogen

The diffusible hydrogen contents in precharged(Co,Fe)3V alloy were measured.It is found that atomic ordering can not promote hydrogen peretration in the(Co,Fe)3V alloy.The ultimate tensile strength(UTS)and ductilities in various condition were also investigated.The results show that the UTS and elongation of disordered alloy are higher than that of ordered one with fixed diffusible hydrogen content and(Co,Fe)3V alloy with ordered structure is highly sus ceprible to the embrittlement in hydrogen gas.The factor which may affect the susceptibility to the embrittlement of (Co,Fe)3V alloy in hydrogen gas in mainly due to that the atomic ordering may accelerate the kinetics of the catalytic reaction for the dissociation of molecular hydrogen into atomic hydrogen.However,it can not be roled out that atomic ordering intensifies planar slip and restricts cross-slip at the grain boundaries and enhances the suscptibility of the alloy to hydrogen embrittlement.