微量Mn,Cu,Ti对AlZnMg合金预渗氢试样应力腐蚀特点的影响

研究了微量添加元素Ｍｎ、Ｃｕ、Ｔｉ对ＡｌＺｎＭｇ合金阴极预渗氢试样的应力腐蚀寿命、截面缩减率和断口形貌的影响。结果表明，预渗氢使合金的应力腐蚀敏感性明显增加，微量添加元素均能改善合金的应力腐蚀性能，其中Ｔｉ的作用最大，Ｃｕ次之，Ｍｎ的作用最小。微量元素的影响可通过它们与合金中氢的交互作用来解释。     

LC4高强铝合金的腐蚀性能研究

利用慢应变速率拉伸试验方法研究了LC4铝合金在空气和3．5％NaCl溶液中的应力腐蚀断裂行为；利用HB5455－90标准研究了LC4铝合金的剥蚀行为；利用HB5255－83标准研究了LC4铝合金的晶间腐蚀行为。结果表明：LC4铝合金具有应力腐蚀敏感性，应力腐蚀的断口形貌受应变速率ε的影响较大；LC4铝合金对剥蚀很敏感，对晶间腐蚀不是很敏感。     

高温预析出对Al-Zn-Mg合金板材应力腐蚀断裂的影响

研究了高温预析出对7A52合金组织、时效硬化和应力腐蚀断裂的影响。结果表明：高温预析出处理在保持7A52合金强度、塑性的同时，可提高合金抗应力腐蚀性能。480℃固溶处理条件下，经过预析出处理后，合金应力腐蚀开裂界限应力强度因子局KISCC由7．6MPa．m^1/2。提高至9．1MPa．m^1/2，475℃固溶处理条件下，经过预析出处理后，KISCC由8．9MPa．m^1/2。提高至11．1MPa．m^1/2;未经预析出处理的7A52合金应力腐蚀断裂区发生严重的阳极溶解腐蚀，晶界和亚晶界均发生断裂，经高温预析出处理后，应力腐蚀裂纹仅沿平行晶界扩展；高温预析出处理使晶界析出相粗化显著、离散度增大且晶界析出相Cu含量提高，这是合金抗应力腐蚀性能得到显著改善的重要原因。     

AZ91D镁合金在两种盐溶液和空气中的一般腐蚀和应力腐蚀

分别在pH值为6的0．60mol/L NaCl,0．60mol/L NaNO_3溶液和空气介质中对AZ91D压铸镁合金进行了一般腐蚀和慢应变速率试验。结果表明：该合金发生的一般腐蚀或应力腐蚀都具有明显的离子选择性,在含Cl~-的溶液中一般腐蚀较严重,在含NO_3~-的溶液中应力腐蚀更为明显。该合金在实验室空气介质中不易发生应力腐蚀。应变速率是该合金发生应力腐蚀的又一重要参数,当应变速率低于8．33×10~(-5)s~(-1)时,该合金在两种溶液中均发生应力腐蚀,在4．17×10~(-5)s~(-1)的应变速率下,应力腐蚀最为严重,应力腐蚀是阳极溶解和氢致开裂共同作用的结果。     

7xxx铝合金的应力腐蚀行为综述（英文）

应力腐蚀是材料在应力和腐蚀环境双重作用下使材料力学性能下降的行为。对于八种系列铝合金,2xxx、5xxx、7xxx铝合金对于应力腐蚀敏感。由于其优越的力学性能,7xxx铝合金广泛应用于航空、军事和结构工业。在这些7xxx铝合金中,应力腐蚀严重影响其力学性能,使其在服役过程中发生灾难性的失效。因此,研究该合金的应力腐蚀行为具有重要意义。本文综述了合金成分对合金在不同热处理条件下的显微组织演变,还综述了改善7xxx合金应力腐蚀性能的形变热处理和表面改性方法。此外,还综述了应力、预应变、合金成分和腐蚀环境对应力腐蚀行为的影响。还综述了焊缝、7xxx金属基复合材料和激光表面处理合金的应力腐蚀行为。     

稳定奥氏体合金(Ni29Co18余Fe)在含Cl~-水溶液中应力腐蚀开裂特性

本文研究了稳定奥氏体合金(4J29)在中性3.5%NaCl 水溶液中的应力腐蚀特征曲线、起裂方式以及扩展特征;研究了此合金在动态充氢条件下的氢致延滞断裂特性。通过对比分析以及管型试样应力腐蚀结果,提出了此合金在含 Cl~-水溶液中的应力腐蚀是以氢致开裂为主的观点。本文通过对比实验还研究了整体介质中 H~+浓度以及 Cl~-浓度对4J29合金应力腐蚀的影响.     

热处理对7075铝合金应力腐蚀及断口形貌的影响

采用预裂纹双悬臂梁(DCB)试样研究了7075铝合金的应力腐蚀行为.结果表明,四种不同热处理状态合金的应力腐蚀敏感性由高向低的排列顺序为T6>G180>RRA>T7351.不同热处理状态的7075铝合金试样在干燥空气中的SSRT拉伸断口形貌都是由韧窝剪切台阶组成,属于韧窝型延性断裂.在3.5%NaCl溶液中,应力腐蚀敏感性较高的T6状态铝合金,其断口形貌是由塑性韧窝和腐蚀平坦区组成的,而应力腐蚀敏感性较轻微的7075-G180铝合金,属韧性断裂.     

8090铝锂合金薄板的应力腐蚀行为

采用慢应变速率试验法(SSRT)就应变速率、极化电位及时效条件的影响等研究了8090铝锂合金薄板在3.5％氯化钠溶中的应力腐蚀行为。其应力腐蚀敏感性随应变速率和极化电位而变化,且存在一个最敏感的应变速率(1×10~(-6)s~(-1))和一个发生应力腐蚀的临界电位(—800 mV,SCE)。8090合金薄板在欠时数状态下对应力腐蚀最敏感,峰时效状态下次之。而过时数状态下则不敏感。根据实验结果和断口形貌特征,认为8090合金薄板的应力腐蚀为阳极活性通道机制,但在强烈渗氢情况下,氢可能成为应力腐蚀的主导因素。     

Al—Li—Cu—Mg合金应力腐蚀性能及机理研究

利用恒应变速率方法研究了Al—Li—Cu—Mg合金的应力腐蚀开裂,包括时效条件及外加电位对应力腐蚀的影响,同时研究了试样表面相对氢浓度与外加电位及应力腐蚀时间的关系,实验结果表明,合金的应力腐蚀性能取决于时效条件,其中峰时效条件下最差,自然时效条件下最好,应力腐蚀敏感性及试样表面氢浓度与外加电位有关,阳极电位增加应力腐蚀敏感性,阴极电位低于临界电位时加速应力腐蚀,认为合金在应力腐蚀过程中阳极溶解与氢脆机制联合作用。     

Al-xMg-3.1Zn铝合金的应力腐蚀开裂行为及其机制

通过慢应变速率拉伸实验和动态电解充氢实验分别研究了Al-x Mg-3.1Zn铝合金的应力腐蚀开裂行为及其氢脆行为。结合宏观断口和微观断口形貌分析研究了合金发生应力腐蚀开裂的进程。通过对合金应力腐蚀开裂的机制进行分析阐明了合金中Mg元素含量对合金应力腐蚀开裂行为的影响。结果表明:在该合金体系中存在应力腐蚀开裂,且合金的应力腐蚀敏感性随合金中Mg含量的降低而降低,这与合金的阳极溶解行为与氢脆行为随Mg元素含量降低而减弱有着直接的关系。在这当中,合金中晶界析出相的数量随Mg元素含量降低而减少起到了至关重要的作用。     

IncoMAPAl—9052合金在3.5%NaCl溶液中的应力腐蚀行为

采用双悬臂梁试样,实验研究了IncoMAP Al-9052合金在3.5％NaCl溶液中的应力腐蚀开裂(SCC)行为。结果表明该种合金的裂纹扩展机制有别于常规的铝合金。其初期阶段的裂纹扩展过程可划分为三个阶段,在每一阶段的裂纹扩展机制可能是不同的,但其裂纹扩展的主要机制为氢脆。     

带镀层GC-4超高强度钢的腐蚀断裂

应用慢拉伸及断裂力学方法研齐了带镀层的GC-4钢(40CrMnSiMoVA)在3.5％NaCl中的应力腐蚀特性,并与裸钢作了对比。结合扫描电镜及宏观断口分析,探讨了失效机理。研究表明,阴、阳极镀层均使钢的KIscc降低,da/dt(Ⅱ)显著增加,其影响依无氰Cd、Cd-Ti、Cr的次序增加。慢拉伸试验结果说明,阴、阳极极化均使GC-4裸钢延性降低。根据BL-WOL试样裂纹扩展在表面处较内部为快以及阴、阳极镀层、平面应变状态对断口形貌的影响,可以认为带镀层与不带镀层GC-4钢的腐蚀断裂机理为裂尖阳极溶解与氢脆共同作用,并且裂尖溶解将直接参与导致裂纹扩展.从而对高强度钢腐蚀断裂的纯氢脆机理作出修正。     

极化和频率对A537钢在3.5%NaCl溶液中的腐蚀疲劳裂纹扩展行为的影响

利用三电极技术研究了极化和频率对A537低合金钢在3.5%NaCl活化体系的腐蚀疲劳的裂纹扩展行为,包括对裂纹扩展速率和断口形貌的影响.结果表明,在活化体系中,强极化条件,频率越小,裂纹扩展速率越大;在阴极保护条件下,频率对裂纹扩展速率的影响很小.阳极溶解和阴极析氢可以增加裂纹扩展速率.裂尖析氢量的大小决定了断口解理面大小.在裂尖塑性区内的位错结构为胞结构,而在塑性区外为长位错线     

SCC MECHANISM OF STAINLESS STEEL AISI 321 IN ACIDIC CHLORIDE SOLUTION

It is verified that stainless steel AISI 321 is in the active anodic dissolution state in 0.5mol/L HCll+0.5 mol/L NaCl solution at 55℃.The SCC of the steel in the solution cannot be reasonably explained by passive film rupture-nepasivation theory and by hydrogenembrittlement theory.There are evidences that the fracture stress at the tip of the cracksis reduced by anodic dissolution due to its role in relieving strain hardening layer at cracktip.     

Effects of testing variables on stress corrosion cracking susceptibility of Al 2024-T351

In the present study, the effects of testing variables on stress corrosion cracking (SCC) susceptibility of Al 2024-T351 in 3.5% NaCl solution were examined using slow strain rate test (SSRT) method with controlled applied potentials and a constant load test (CLT) method. The SSRTs were conducted at various strain rates and applied potential, while the CLTs were performed with different exposure time, with different grain directions of ST (short-transverse) and L (longitudinal) to understand how the testing parameters affected on the SCC susceptibility of Al 2024-T351. The percent reductions in tensile elongation in an SCC-causing environment over those in air tended to express the SCC susceptibility of Al 2024-T351 most properly for both SSRT and CLT. The present fractographic examination suggested that both anodic dissolution and hydrogen embrittlement played a role in the SCC process of Al 2024-T351 in 3.5% NaCl solution at both anodic and cathodic applied potentials, and the contribution of each mechanism could vary with different testing variables. It was also found that the SCC susceptibility of Al 2024-T351 obtained from the CLT result could provide the similar SCC evaluation result obtained by SSRT with a proper selection of testing variables. The metallurgical aspect of SCC behaviour of Al 2024-T351 was also discussed based on the microstructural and fractographic examinations.     

X70管线钢在近中性及高pH值溶液中的电化学行为和SCC敏感性

采用动电位极化曲线测试法研究了温度、通气条件和pH值对X70管线钢在NS4溶液和0.5 mol/LNa2CO3 1 mol/L NaHCO3溶液中的电化学极化行为的影响,并用慢应变速率试验(SSRT)研究了X70管线钢在这些溶液中的应力腐蚀破裂(SCC)敏感性。结果表明,X70管线钢在NS4溶液中不出现活化—钝化转变区,随外加电位负移,SCC敏感性增加,表现出氢致破裂(HIC)的特征;在0.5 mol/L Na2CO3 1 mol/L NaHCO3高pH值溶液中出现活化—钝化转变区,在阴极极化区,也表现出氢致破裂(HIC)的特征,但在阳极极化区,发生的是阳极溶解型应力腐蚀破裂(ADSCC)。     

颗粒增强SiCp／2024铝基复合材料的应力腐蚀断裂行为

通过双悬臂梁试样试验和慢应变速率拉伸试验，研究了ＳｉＣｐ／２０２４铝基复合材料在ＮａＣｌ水溶液中的庆力腐蚀断裂行为，并探讨了增强体的存在对材料ＳＣＣ行为的影响。发增强体的存在并未使材料的ＳＣＣ机理发生本质上的变化，但使复合材料的ＳＣＣ抗力明显高于普通铝合金的。     

铝合金稀土转化膜处理对LC4合金耐SCC性能的影响

利用慢应变速率试验(SSRT)等方法研究了P5和SRE稀土转化膜处理对LC4铝合金在3.5%NaCl溶液中的应力腐蚀行为的影响。P5和SRE工艺对LC4合金的应力腐蚀有一定抑制作用,SRE处理液对SCC有缓蚀效果。     

Stress corrosion cracking and hydrogen embrittlement susceptibility studies on modified 9Cr-1Mo steel weldments in acidic and neutral media

Abstract

There is much scope for the development of new engineering materials for high temperature applications such as for tubing used in steam generation in fossil fuel and nuclear power plants and in petrochemical cracking units. The materials for such applications are often manufactured from mild steel and low alloy ferritic steels containing up to 9%Cr. Modified 9Cr-1Mo ferritic steel, prepared by incorporating vanadium and niobium, is one of the newer materials extensively used for high temperature applications. A study of weldments of this alloy and its susceptibility to stress corrosion cracking (SCC) and hydrogen embrittlement was carried out in acidic and neutral media. The anodic behaviour of modified 9Cr-1Mo under 90% proof stress was also examined. Mechanical properties of the material were assessed before and after SCC and hydrogen embrittlement tests. The SCC tests were made at various anodic potentials in 1M H₂SO₄ and showed that the welded alloy is not susceptible to SCC in all three critical zones. The alloy was, however, susceptible to SCC in chloride environments, namely a solution containing equal volumes of 1M NaCl and 1M MgCl₂. Fractographic analysis was carried out to determine the reasons for the failure of this alloy. The hydrogen embrittlement studies in 1M H₂SO₄ showed that the alloy is prone to delayed hydrogen cracking at more negative potentials. The fractographic examination using scanning electron microscopy revealed the presence of adsorbed hydrogen in microvoids which were responsible for the failure of the alloy. Other possible reasons for the failure of the alloy are also discussed.