Stress corrosion cracking of high-strength drill pipe in sour gas well

In high sour gas reservoir drilling process, it happens occasionally that high-strength drill pipe suffers brittle fracture failure due to stress corrosion cracking, and poses serious hazard to drilling safety. To solve this problem, this paper studied the stress corrosion cracking mechanism and infl uencing factors of highstrength drill pipe in sour environment with hydrogen permeation experiments and tensile tests. We simulated practical conditions in laboratory and evaluated the stress corrosion cracking performance of the high-strength drill pipe under conditions of high stress level. For the problems occurring in use of high-strength drill pipe on site, the paper proposed a technical measure for slower stress corrosion cracking.     

镁合金应力腐蚀开裂敏感性影响因素及防护措施

在腐蚀性环境中,镁合金具有十分强烈的应力腐蚀敏感性,往往降低材料性能,制约镁合金的应用.基于近些年来镁合金应力腐蚀开裂导致了一系列工业事故频繁发生的事实,需要了解和重视镁合金应力腐蚀开裂敏感性的影响因素及防护方法,针对影响镁合金应力腐蚀开裂敏感性的各项因素进行了综合的分析,并从应力,腐蚀环境,合金品质等方面对国内外镁合金应力腐蚀开裂防护措施的最新进展进行了介绍,并提出了镁合金应力腐蚀及防护领域未来所面临的任务.     

金属材料应力腐蚀失效分析

本文研究了金属材料应力腐蚀断裂的发生条件、断裂的特征、测试的方法、断裂的原因和解决的方法,对金属材料应力腐蚀断裂的判断和分析并解决应力腐蚀断裂的问题提供了重要依据。     

石化火炬燃烧器管线裂纹开裂失效分析

研究了火炬燃烧器管线开裂区域的破坏机理,通过对管线进行低倍宏观分析、材质分析、显微镜金相分析、扫描电子显微镜（SEM）微观形貌及能谱分析（EDS）与实验相结合的手段,找出了管线失效开裂的原因,进一步分析了敏感环境（介质）、敏感材料和应力状况对管线开裂失效造成的影响。结果表明,在一定的温度下,管线内形成H₂S＋CO₂＋H₂O的酸性腐蚀环境,火炬燃烧器管线的不锈钢材质敏化严重,存在严重的晶间腐蚀;晶间腐蚀造成管壁表面晶粒剥落,产生点蚀坑,点蚀坑处又成为应力腐蚀裂纹的裂纹源;火炬燃烧器管线在制造加工、装置运行等过程中会产生一定程度的应力集中,在腐蚀介质、敏感材质和应力集中三个因素的影响下,火炬燃烧器管线会发生晶间型应力腐蚀开裂而失效。     

Effect of hydrogen on the stress corrosion cracking behavior of X80 pipeline steel in Ku'erle soil simulated solution

Hydrogen was a key factor resulting in stress corrosion cracking (SCC) of X80 pipeline steel in Ku'erle soil simulated solution. In this article, the effect of hydrogen on the SCC susceptibility of X80 steel was investigated further by slow strain rate tensile test, the surface fractures were observed using scanning electron microscopy (SEM), and the fracture mechanism of SCC was discussed. The results indicate that hydrogen increases the SCC susceptibility. The SEM micrographs of hydrogen precharged sample...     

Relativity between corrosion—induced stress and stress corrosion cracking of brass in an ammonia solution

The susceptibility to stress corrosion cracking (SCC) of brass in an ammonia solution with various pH values or under various applied potentials was measured at slow strain rate tests. The additive stress in the same solution was measured using two methods. The results indicate that the variation of the susceptibility to SCC with pH value or with potential is in an excellent agreement with the corrosion (passive film or dezincification layer)-induced stress. When pH≥7, the corrosion-induced tensile stress andthe susceptibility to SCC have maximum values and hardly change with increasing the pH value. However, when pH < 7, both the corrosion-induced tensile stress and the susceptibility to SCC reduce rapidly with decreasing the pH value. Both the corrosion-induced tensile stress and the susceptibility to SCC have maximum values at the open-circuit potential, decrease slightly under the anodic polarization, and reduce gradually to zero under the cathodic polarization.     

房屋建筑墙体开裂的原因及应对措施

根据近几年施工中的经验,分析了墙面裂纹产生的原因以及以往施工方法的得失,查阅有关资料,尝试着在砌筑及抹面砂浆中掺加膨胀剂,以砂浆自身适度膨胀抵消收缩裂纹.虽然这一方法尚不成熟,但确实值得同行们继续共同关注、探讨.     

Analytic model of non-uniform corrosion induced cracking of reinforced concrete structure

In order to perfectly reflect the dynamic corrosion of reinforced concrete (RC) cover in practical engineering,an analytic model of non-uniform corrosion induced cracking was presented based on the elastic-plastic fracture mechanics theory.Comparisons with the published experimental data show that the predictions given by the present model are in good agreement with the results both for natural exposed experiments and short-time indoor tests (the best difference is about 2.7%).Also it obviously provides muc...     

Characteristic surface oxide film cracking behavior of a Fe-Ni-Cr Alloy under in-phase and out-of-phase thermo-mechanical fatigue

The surface oxide film cracking behavior of Fe-30Ni-20Cr alloy under in-phase and out-of-phase synchronizing thermal cycling with mechanical cycling was studied.Surface oxide film cracking along the grain boundary under in-phase overlapping was creep predominant fracture mechanisms.Strongly induced slip lines preceding were accompanied by the surface oxide film cracking under Out-of phase,and the shear cracking was dominant mode.Negative mean stress could counteract a part of the tensile component of alternative stress,so as to delay the cracking process under in-phase,but positive mean stress overlapping the tensile alternative stress could accelerate the cycling cracking process under out-of-phase.     

受约束早龄期混凝土收缩开裂的理论预测和试验研究

金南国，金贤玉，田野为了揭示受约束混凝土内部的应力发展以及更好地预测混凝土的开裂时间，研究了纤维对高性能混凝土早龄期力学性能与干燥收缩的影响，考虑徐变、约束度等影响因素，在弹性理论基础上，推导了受约束混凝土环应力增量表达式，采用应力破坏准则预测受约束混凝土开裂时间.研究结果表明，在特定的配合比下，掺加聚丙烯腈纤维使混凝土各龄期的干燥收缩应变降低2％～20％，且降低幅度随着龄期的增加而减小；掺加聚丙烯腈纤维可以延迟混凝土的开裂时间，减小裂缝宽度.针对受约束混凝土环，理论预测掺纤维与未掺纤维混凝土的开裂时间分别为28和22 d，理论预测结果与试验结果吻合良好.     

水泥混凝土路面早期裂缝影响因素分析

利用美国HIPERPAV软件对水泥混凝土路面早期裂缝的主要影响因素进行模拟。系统分析研究了路面板厚度、粉煤灰掺加量、养护方式、施工时间、施工季节和切缝等各因素对早期裂缝的影响规律。数据分析结果表明,夏季施工的路面板应力强度比与冬季施工的路面板应力强度比相比要低很多;不切缝的路面板要比切缝的路面板容易产生早期裂缝;另外,选择合理的混凝土配合比、施工时间和养护方式对早期裂缝也有着明显地改善作用。     

Corrosion-enhanced dislocation emission and motion resulting in initiation of stress corrosion cracking

A special constant deflection device for TEM has been designed, and then change of dislocation configuration ahead of a crack tip during stress corrosion cracking (SCC) of brass in water and of Ti-24Al-11Nb alloy in methanol and initiation of SCC can he observed in TEM In situ tensile test in TEM for brass was carried out for comparison The results show that anodic dissolution during SCC can facilitate dislocation emission, multiplication and motion, and a dislocation free zone (DFZ) is formed The stress at a particular site in the DFZ, which is an elastic zone and is thinned gradually through corrosion-enhanced dislocation emission and motion, is possibly up to the cohesive strength, resulting in initiating of a nanocrack of SCC in the DFZ or sometimes at the crack tip. Because of the action of the corrosion solution the nanocrack of SCC propagates into a cleavage or intergranular microcrack rather than blunts into a void like in situ tension in TEM     

关于某糖厂锅炉爆管事故的分析与研究

针对某糖厂的SHS35-2.45/400-GA1型热电联产锅炉发生的一起爆管事故,从锅内过程、锅炉钢材金相组织的改变及国家相关锅炉规范等进行了技术分析研究。认为主要原因是由于水冷壁管内水循环故障引起的水冷壁爆管,造成锅炉严重缺水而使锅炉受热面大面积损坏,导致了此次锅炉事故。锅炉缺水主要是因为电控仪表设置的缺陷和错误以及操作人员处理不当造成的。该糖厂锅炉事故具有典型性,事故研究与分析对其它糖厂可提供借鉴作用。     

轻烃裂解催化剂的反应与再生行为研究

在小型气固反应系统中,考察了不同反应条件下轻烃裂解催化剂H0108与1-P-H0108的反应性能,发现通水条件下有助于提高乙烯、丙烯收率,防止催化剂表面结焦,但对催化剂的结构稳定性有影响,尤其是催化剂H0108稳定性较差.对失活后的催化剂进行TG/DTG表征,结果表明,无水条件下两种催化剂表面均存在两种类型积炭,经750 ℃空气烧炭再生后恢复活性,说明结焦是引起催化剂失活的主要原因;通水条件下,也存在结焦失活,但催化剂通过烧炭只能部分恢复活性;通过催化剂的NH3程序升温脱附（NH₃-TPD）表征,表明通水条件下不可逆的结构性变化可能是催化剂活性只能部分再生的主要原因.     

CO2增采环境下X70管线钢的应力腐蚀开裂行为研究

在CO₂增采（CCS?EOR）环境下,研究了X70管线钢在不同CO₂压力下的腐蚀开裂行为及其机理。 使用高压反应釜及模拟采出水溶液,对现场环境进行了模拟;通过电化学实验,研究了X70管线钢在CCS?EOR环境下的腐蚀速率与腐蚀机理;通过慢应变速率拉伸实验,研究了模拟环境下X70管线钢的腐蚀开裂行为;通过扫描电镜,分析了不同CO₂压力下X70管线钢的腐蚀开裂机理。 结果表明,X70管线钢的腐蚀速率随着CO₂压力的增加而增加;X70管线钢表面产生的腐蚀产物膜不能保护金属基体,而且加剧局部腐蚀;在腐蚀产物膜的影响下,CO₂压力的增高使X70管线钢应力腐蚀敏感性增加,X70管线钢腐蚀开裂同时受金属表面裂纹的影响。     

基于热力耦合的钢筋混凝土锈胀开裂分析

为对锈蚀钢筋混凝土构件开裂问题进行分析,鉴于氯离子扩散控制方程与瞬态热传导控制方程的相似性,根据传统的Fick定律和已有的氯盐环境下钢筋非均匀锈胀模型以及热弹性力学理论,提出钢筋混凝土锈胀开裂模拟的热力耦合方法.对氯离子的扩散采用瞬态热传导方法进行分析模拟,提取各时间步钢筋单元表面的氯离子质量浓度即温度作为混凝土的温度荷载,引入钢筋锈胀的时变等效温度膨胀系数,采用升温膨胀对钢筋的锈胀以及由此引起的混凝土开裂过程进行有限元分析.数值算例表明,该方法可以有效地模拟和分析钢筋的非均匀锈胀和混凝土的裂缝扩展行为.     

沥青胶结料低温临界开裂温度计算的改进方法

针对当前沥青胶结料温度应力和低温临界开裂温度计算方法的局限性,为找寻一种更好的沥青胶结料温度应力及相应的低温临界开裂温度计算方法,选取4种不同产地的70^#基质沥青进行旋转薄膜老化（RTFO）和压力箱老化（PAV）展开研究. 利用BBR试验获得沥青胶结料的蠕变柔量,分别采用Hopkins & Hamming算法和CAM模型两步计算法以及Laplace变换一步计算法获得了沥青的温度应力,基于SAP理论计算相应的低温临界开裂温度. 通过统计学方法对计算结果进行比较和分析,采用相关性分析并结合实测路表温度数据对计算方法予以验证. 结果表明:Laplace变换一步计算法和Hopkins & Hamming算法两步计算法具有良好一致性,基于t检验法的低温临界开裂温度p值计算结果达0.90以上. Laplace变换一步计算法与BBR试验具有较强的相关性,临界开裂温度T_CR与S/m指标、Huet流变模型指标的相关系数分别可达0.84、0.94. 实测路表温度变化数据的计算结果证明了该方法不仅适用于匀速降温工况,也适用于任意降温速率下的现场连续变速降温工况.     

钢筋混凝土构件锈蚀开裂与锈胀力分析

为合理确定锈胀力大小及其变化规律,研究混凝土保护层在锈胀作用下的开裂过程,提高混凝土结构使用寿命. 在考虑混凝土材料受拉软化和损伤效应的基础上,通过改变保护层厚度、钢筋直径、混凝土强度等参数,对钢筋锈胀引起的混凝土开裂过程、锈胀力分布和变化过程进行了有限元模拟和分析. 结果表明:均匀锈蚀下钢筋圆周上各处锈胀力分布并不均匀,明显受到内部裂缝的影响;锈胀力在裂缝贯通前达到峰值,之后快速下降最终保持稳定;保护层厚度c和钢筋直径d对锈胀的影响为线性关系,且统一用c/d值表征这两个参数是合理的,c/d值越大保护层完全开裂时的锈胀力和锈蚀率也越大,即延缓了保护层开裂. 基于锈胀力与c/d值的变化关系提出了最大锈胀力公式,并通过试验数据比对验证了最大锈胀力公式的有效性与精度.      

施工阶段大跨径预应力混凝土刚构桥腹板开裂机理

进行了大跨径预应力混凝土刚构桥腹板开裂机理研究,基于弹性力学平面问题分析方法,推导了集中荷载作用下的板件应力函数表达式,绘制了不同受压边长与集中荷载长度比（d/a）下的横向应力曲线,拟合了集中荷载作用下构件的横向应力求解函数,构造了混凝土刚构桥腹板在预应力集中荷载作用下等效压力矩形的选取方法,并基于平面应力的表达式提出了在三维情况下沿预应力轴线的横向应力计算方法。通过建立某预应力混凝土刚构桥0~3#段实体有限元模型,分析施工过程中刚构桥混凝土腹板在不同等级预应力作用下的开裂情况。结果显示：有限元裂缝模拟与实桥腹板开裂范围一致,有限元应力分析结果下限值与推导的横向应力求解函数计算结果接近,变化趋势一致,印证了横向应力函数求解方法的正确性。     

残余应力的产生和对腐蚀开裂的影响研究

分析了机械零件残余应力的产生原因和应力腐蚀开裂的基本条件,通过实验论述了残余应力对腐蚀开裂的影响,为控制已加工表面的残余应力提供了理论依据．