BEHAVIOUR AND MECHANISM OF STRESS CORROSION CRACKING FOR Al-Li-Cu-Mg ALLOY

Studies were made of the influence of aging conditions and applied potentials on thestress corrosion carcking(SCC)susceptibility for an Al-Li-Cu-Mg alloy by slow strainrate technique.The relationship between the relative hydrogen content on specimensurface,the applied potentials and elapsed time has also been examined.The SCCsusceptibility was found to be dependent on aging conditions in which the peak agedcondition gave the worst SCC resistance and the natural aged condition had the best one.The SCC susceptibility and surface hydrogen content relates to the applied potentials.The anodic potentials increase SCC susceptibility,while the cathodic ones below thecritical potential accelerate SCC.It is considered that both the anodic dissolution and     

STRESS CORROSION CRACKING AND HYDROGEN INDUCED CRACKING OF ORDERED B_2－TYPE Fe_3Al

用ＷＯＬ恒位移试样研究了Ｂ_２结构的Ｆｅ_３Ａｌ和Ｆｅ_３Ａｌ＋Ｃｒ的应力腐蚀和氢致开裂．结果表明，水中应力腐蚀的门槛值和裂纹扩展速率均高于动态充氢时的相应值加Ｃｒ能提高Ｆｅ_３Ａｌ的Ｋ_（ＩＣ），Ｋ_（ＩＳＣＣ）和Ｋ_（ＩＨ）．氢致开裂断口随Ｋ_Ｉ下降由解理向沿晶转变，水中应力腐蚀则全是解理断口，这与Ｋ_（ＩＳＣＣ）较高有关．     

EFFECT OF POTENTIAL ON INTERACTION BETWEEN STRESS CORROSION CRACKING AND CORROSION FATIGUE OF AUSTENITIC STAINLESS STEEL IN BOILING 42% MgCl_2 SOLUTION

The environment-sensitive fracture behaviour of 0Cr18Ni9Ti austenitic stainless steel inboiling 42% MgCl_2 under the specific load of low frequency and high mean stress was inves-tigated from the relations and differences of crack growth rates and fractographs betweenstress corrosion fatigue and stress corrosion cracking.The interaction between stress corro-sion cracking and corrosion fatigue was also studied from fracture characteristics with empha-sis on the effects of applied potential on the interaction.     

STRESS CORROSION CRACKING OF 304L STAINLESS STEEL IN WATER AT 288℃

敏化的304L不锈钢紧凑拉伸试样在288℃的含氧循环水中发生应力腐蚀(SCC)后，沿试样横截面将裂纹尖端区制成透射电镜(TEM)试样，用高分辨分析型TEM观察裂尖，测量微区成分．结果表明，在不连续的SCC裂纹周围及裂尖前方存在几百纳米宽的氧化物区，成分为Cr2O3，Fe3O4或其混合物．在氧化物中存在大量的纳米级浅裂纹，在裂尖应力集中作用下，氧化物中首先形成不连续的微裂纹，它们长大并和主裂纹连接就导致SCC裂纹的不连续形核及扩展．     

STRESS CORROSION CRACKING IN HIGH STRENGTH STEEL UNDER MODE Ⅲ LOADING

研究了超高强度钢Ⅲ型缺口试样在水介质中的应力腐蚀,并与动态充氢条件作了对比。结果表明,超高强度钢Ⅲ型试样在水介质中能产生应力腐蚀,而且裂纹沿着和原缺口面成45°的平面形核和扩展,获得沿晶断口。这些都和Ⅲ型试样动态充氢时氢致开裂的情况相同。水介质中加硫脲,能使Ⅲ型和Ⅰ型的应力腐蚀门槛值明显下降,如动态充氢,则使裂纹的孕育期和门槛值进一步下降,实验也表明,无论动态充氢还是应力腐蚀,Ⅲ型试样的门槛值均比Ⅰ型要高,这可用Ⅲ型和Ⅰ型的平衡氢浓度不同来解释。     

ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY DURING CORROSION PROCESS OF 8090 Al-Li ALLOY IN EXCO SOLUTION

1.IntroductionAl-Li alloys, compared to traditional Al alloys, have more excellent properties, such as lower density, greater elastic modulus and higher specific strength[1,2]. In the near future, they would be widely applied to airplane structures. While, exfoliation, a main kind of localized corrosion, lowers their strength, plasticity and fatigue properties, and also decreases their service life[3, 4]. So investigating their exfoliation would be very important to their application.Usua…     

Ti－24Al－11Nb腐蚀疲劳断口形貌的研究

Ｔｉ－２４Ａｌ－１１Ｎｂ腐蚀疲劳断口形貌的研究张跃，褚武扬，王燕斌，肖纪美（北京科技大学北京１０００８３）１引言对Ｔｉ－２４ＡＩ－１１Ｎｂ合金的断裂特征和断口形貌已进行了较多的研究［“］．在３００ｏＣ的氢气中该合金能发生氢致开裂，其断口形貌与过载断口...     

SEAWATER CORROSION OF A Cu-Ni ALLOY IN INTERMITTENT IMMERSION

ＳＥＡＷＡＴＥＲＣＯＲＲＯＳＩＯＮＯＦＡＣｕＮｉＡＬＬＯＹＩＮＩＮＴＥＲＭＩＴＴＥＮＴＩＭＭＥＲＳＩＯＮ①ＺｈｕＸｉａｏｌｏｎｇ，ＬｉｎＬｅｙｕｎ，ＬｉＺｈｏｎｇｊｉａｎＧｅｎｅｒａｌＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅｏｆＮｏｎＦｅｒｒｏｕｓＭｅ...     

EFFECTS OF STRESS RATIO AND FREQUENCY ON CORROSION FATIGUE CRACK GROWTH MECHANISM IN LOW ALLOY STEELS

Based on theoretical analysis about local strain,strain rate and dissolving rate at crack tip,the corrosion fatigue crack growth rate of steels ZG20SiMn and SM50B-Zc in fresh waterand 3.5% NaCl solution were measured experimentally,and the PH and electrode potentialwithin crack were also measured continuously along with crack propagating.It showed thatthe increase of crack growth rate,caused by both decreasing frequency and raising stressratio,was mainly accelerated by hydrogen embrittlement.     

HIGH TEMPERATURE CORROSION OF PREOXIDIZED Ni-Al ALLOY IN CHLORINE

ＨＩＧＨＴＥＭＰＥＲＡＴＵＲＥＣＯＲＲＯＳＩＯＮＯＦＰＲＥＯＸＩＤＩＺＥＤＮｉ－ＡｌＡＬＬＯＹＩＮＣＨＬＯＲＩＮＥＨＩＧＨＴＥＭＰＥＲＡＴＵＲＥＣＯＲＲＯＳＩＯＮＯＦＰＲＥＯＸＩＤＩＺＥＤＮｉ－ＡｌＡＬＬＯＹＩＮＣＨＬＯＲＩＮＥ￥Ｔｕ，Ｊｉａｎｇｐｉ...     

Ti_3Al＋Nb在甲醇中沿相界的应力腐蚀SCIEI

研究了Ｔｉ－２４Ａｌ－ｌｌＮｂ合金中Ｔｉ３Ａｌ＋Ｎｂ金属间化合物在甲醇溶液中的应力腐蚀及室温氢致开裂的规律，探讨了组织结构的影响．结果表明，Ｔｉ３Ａｌ＋Ｎｂ在甲醇溶液中应力腐蚀敏感性很高，不向组织应力腐蚀断裂归一化门槛值为而ｋ（ＩＳＣＣ）／ＫＣ＝０．５３－０．６９；应力腐蚀裂纹止裂门槛值为Ｋ（ＩＳＣＣ）／Ｋ（ｌｉ）＝０．６１－０．７９．Ｔｉ３Ａｌ＋Ｎｂ在室温动态充氢时能发生氢致开裂，门槛值和应力腐蚀相近，但裂纹扩展速率或断裂时间比应力腐蚀要慢１－３个数量级．两者断口形貌也不相同．发现了相界应力腐蚀现象．对固溶后炉冷试样，当ＫＩ较低时，应力腐蚀裂纹优先沿α２／β相界形核和扩展，从而获得相界应力腐蚀断口．如固溶后空冷或ＫＩ较高，则不出现相界应力腐蚀．     

Ti－24Al－11Nb金属间化合物的氢致滞后开裂

Ｔｉ－２４Ａｌ－１１Ｎｂ金属间化合物的氢致滞后开裂张跃，王忆，王燕斌，褚武扬，肖纪美（北京科技大学北京１０００８３）１引言复相金属间化合物Ｔｉ－２４ＡＬｌｌＮｂ合金是一种重要的新型高温结构材料，已被美国宇航局用作为新一代宇航飞机的发动机材料及结构件．...     

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。     

50Mn18Cr4WN奥氏体钢的应力腐蚀和氢致开裂

本文采用悬臂弯曲预裂纹试样应力腐蚀试验方法和紧凑拉伸试样恒载荷法测定了50Mn18Cr40WN奥氏体钢在含C1-和NO3-的水溶液中应力腐蚀以及电解充氢条件下氢致开裂的门槛值,并对应力腐蚀和氢致开裂的裂纹走向与断口形貌进行了观察.50Mn18Cr4WN钢在含C1-和NO3-的水溶液中均能产生应力腐蚀开裂,且在含NO3-的水溶液中比在含C1-的水溶液中应力腐蚀敏感性大.在电解充氢条件下,50Mn18Cr4WN钢也能产生氢致开裂.     

纯铝基复合材料的应力腐蚀与氢致开裂

采用双悬臂梁（DCB）恒位移试验方法，Ⅱ型恒载荷试验方法以及慢为速率拉伸（SSRT）试验方法对纯Al复合材料的应力腐蚀与氢致开裂行为进行了研究，结果表明，在不发生应力腐蚀与氢致开裂的纯铝中加入20％（体积分数，下同）的SiC晶须或Al18O33晶须后就会发生应力腐蚀及氢致开裂。     

Ti—24Al—11Nb氢致脆断的分形研究

导出了使裂纹脆性扩展的外加应力场强度因子K_I和断口分形维数D_F的关系式其中d_f是断裂单元尺寸,L_o是常数,γ是真实表面能,E’=E或E/(1-v~2)测出1nk_1-D_F直线就可获得真实表面能γ、此方程适用于过载断裂和滞后断裂(如氢致开裂和应力腐蚀) 实验表明,Ti—24Al—HNb在动态充氢时能发生氢致滞后断裂,且门槛值较低,K_(IH)/K_(IC)=0.43实验测出的K_(IC)和氢致裂纹扩展的外加应力场强度因子K_I与其断口D_F的关系和上述理论公式一致     

Ti—24Al—11Nb合金感应凝壳熔炼（ISM）过程中Al元素的挥发损失行为

计算了Ｔｉ－２４Ａｌ－１１Ｎｂ中各组元的活度系数,在此基础上系统地研究了该合金在冷坩蜗感应凝壳熔炼过程中Ａｌ的发挥发损失行为。计算结果表明外压为０．１３３Ｐａ时,在１９００－２２００Ｋ的范围内,Ａｌ的挥发由界由挥发反应和液相界面层中的扩散同时控制作用。     

高强钢应力腐蚀门槛值随强度的变化规律

恒位移试样测量表明,４０ＣｒＭｏ钢在３．５％ＮａＣｌ水溶液中应力腐蚀（ＳＣＣ）门槛应力强度因子ＫＩＳＣＣ随屈服强度σｓ指数下降、即ＫＩＳＣＣ＝１．３８×１０６ｅｘｐ（－８．２６×１０－３σｓ）．动态充氢时氢致开裂（ＨＩＣ）门槛应力强度因子ＫＩＨ随试样中可扩散氢浓度Ｃ０（１０－６）的对数而线性下降,即ＫＩＨ＝３１．１－９．１１ｎＣ０． ＳＣＣ时也遵循这个规律．发生ＨＩＣ型ＳＣＣ的临界氢浓度Ｃｔｈ随σｓ指数下降,从而可导出ＫＩＳＣＣ＝ａｋ１ｅｘｐ（－ｋ２σｓ）;其中ａ＝３ＲＴ　／２（１＋ν）ＶＨ,ＲＴ是热能,ρ是裂纹止裂时的曲率半径,ＶＨ是氢在钢中的偏摩尔体积,ν为Ｐｏｉｓｓｉｏｎ比,ｋ１和ｋ２则是和成分及组织有关的常数．