共查询到20条相似文献,搜索用时 62 毫秒
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某炼化企业于上世纪70年代建造的2台液化气球罐,投用3个月就发生开裂泄漏,经修复带缺陷运行,在服役30年后,因应力腐蚀开裂报废。本文结合硫化氢应力腐蚀开裂的机理和影响因素,对这两台液化气球罐的运行条件进行了深入分析,给出了液化气球罐运行安全控制建议。 相似文献
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球罐是十分重要的压力容器,广泛地应用在石油化工行业,针对Q370R钢制液氨球罐,采用科学的方法确定了裂纹产生的原因。不严格执行正确的焊接工艺,造成焊接接头硬度高、残余应力大,产生了氢致裂纹,在介质作用下,引发了大量应力腐蚀裂纹。并给出了以硬度标准的返修判据和焊接操作要点,不仅能够保证返修质量,还能够防止产生新裂纹。 相似文献
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采用微电极体系和试样背后打孔技术,对300M超高强度钢在3.5%NaCl水溶液中腐蚀疲劳裂纹尖端微区溶液电化学行为进行研究,在极化和无极化条件下分别测试裂化溶液的电位△E和pH值的变化,结果发现,无极化条件下,裂尖pH下降,电位上升,裂尖前沿电位和pH值随裂化分布不均匀,在极化条件下,裂尖电化学特征随极化电位变化而表现不同,基于裂尖电化学行为规律,对腐蚀疲劳裂放展规律进行解释。 相似文献
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本文研究了16MnR钢的应变疲劳裂纹扩展特性,用逐级递增位移双引伸计法测定了16MnR钢的应变疲劳裂纹扩展速率,给出了裂纹扩展速率与循环J积分范围△J,循环裂尖张开位移范围△δt的关系。结果表明,存应变循环条件下,循环J积分与COD这两个相互独立的断裂参量存在着内在的关系:△J=kσ_(?)△δ_t。 相似文献
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韩恩厚 《腐蚀科学与防护技术》1992,4(4):270-276
以单边穿透裂纹为背景,建立了描述腐蚀疲劳裂纹内溶液的流体运动两维方程。通过解偏微分方程组,用解析法得到了腐蚀疲劳裂纹内溶液的两维运动规律。据此,以紧凑拉伸试样为例,讨论了影响速度的各参数及裂纹内的流态。 相似文献
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本文从液体的粘滞流动特性出发,导出了无机盐水溶液引起的裂纹闭合应力强度因子分量的定量表达式,并进行了有关计算.计算结果表明,对于负脉冲波,由液体粘滞性引起的裂纹闭合作用不可忽视.而对非脉冲波形,液体粘滞性作用可忽略不计.文中还对GC-4(40CrMnSiMoVA)钢在3.5%NaCl溶液中的方波(SQ)与负脉冲波(NP)腐蚀疲劳裂纹扩展特性进行了试验性对比研究.试验结果表明,△K<15.58MPa时,(da/dN)NP<(da/dN)SQ试验结果验证了定量计算结果. 相似文献
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变幅载荷下铝合金的腐蚀疲劳裂纹起始寿命 总被引:1,自引:0,他引:1
试验测定了铝合金切口件在变幅块谱下于3.5%NaCl溶解中的腐蚀疲劳裂纹起始(CFCl)寿命,结果表明,变幅载荷谱中的大超载会显著延长CFCI寿命,并用超载方式和加载顺序具有明显的影响,根据反映大小载荷交互作用和腐蚀效应的超载CFCI寿命曲线,探讨了应用Miner累积损伤定则建立变幅载荷下切口件CFCI寿命估算模型的可行性,并应用平均秩对变幅块谱下CFCI寿命的分布进行了统计分析,讨论了变幅载荷谱 相似文献
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应用弹塑性断裂力学和△J参数,研究了16Mng钢短裂纹的纯机械疲劳和氢蚀疲劳特性。并用da/dN=C(△J)^n计算了裂纹的扩展速度和门槛值。用金相法考察了裂纹扩展途径。结果表明,氢的渗入降低了裂纹扩展的门槛值,加速了裂纹的扩展速度。 相似文献
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某液化石油气贮罐在定期检验中,发现其焊缝内表面存在大量裂纹,通过材质、硬度、宏观、金相等方面的分析,表明,裂纹属于典型的应力腐蚀开裂。通过对应力腐蚀机理、介质环境、应力水平等方面的探讨,分析了该罐发生应力腐蚀开裂的成因,并针对开裂原因有针对性的提出了一些防范措施。 相似文献
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The stress corrosion cracking (SCC) behaviour of AISI 304 pipe girth welds which were welded by a single-pass laser beam welding (LBW) and a multi-pass tungsten inert gas welding (TIG),respectively,was studied by the slow strain rate tests combined with the electrochemical corrosion tests.The results show that fracture of both the TIG joint and LBW joint occurs in the heat-affected zone (HAZ).According to the electron-backscattered diffraction observation of the microstructures,comparison of potentiodynamic polarization curves and X-ray photoelectron spectroscopy analysis of corrosion products on HAZs of the two joints after the electrochemical tests,the LBW joint exhibits better SCC resistance than the TIG joint in corrosion environments,due to the synthetic effect of more Cr2O3 in corrosion products,finer grains,lower residual strain and higher δ-ferrite content in its HAZ.Although the TIG joint has better mechanical property,considering lower SCC susceptibility and higher production efficiency of the LBW joint,the LBW promisingly replaces the TIG for welding of AISI 304 pipes in the nuclear power industry. 相似文献
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铝镁合金是未来应用汽车领域发展具有很大潜力的一类重要材料.通常,在商品中的铝镁合金,镁的质量分数在0.5%~13%.汽车制造商通常选用镁的质量分数在4.5%以上,然而研究发现,当镁的质量分数超过3%的时候,会引起晶界间腐蚀,从而造成应力腐蚀开裂.此现象未见文献对其进行系统的分析和研究.本文主要介绍铝镁合金在不同的热处理... 相似文献
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研究了时效制度对Al-Zn-Mg-Cu合金(LC4)双悬臂梁(DCB)试样的残余应力分布及其对应力强度因子、腐蚀开裂行为的影响。结果表明,轴向残余拉应力可以引起试样弯曲成弓形,相当于DCB试样附加一应力强度因子K1R,K1R随时效温度提高而减小。在自然时效状态K_(1R)约10MPa·m ̄(1/2),120℃时效时态K_(1R)约7.5MPa·m ̄(1/2)时,无外加载荷均可产生严重的腐蚀开裂现象,且具有沿晶断裂特征并呈特殊的长舌形区。160℃时效状态未出现腐蚀开裂现象,对其原因进行了讨论。 相似文献
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裂纹尖端氧化膜形成与破裂是核电站压力容器高温水环境中镍基合金材料应力腐蚀开裂(SCC)的主要过程之一。由于应力腐蚀裂纹尖端形貌和扩展方式的特殊性,本研究利用ABAQUS有限元软件的子模型技术,在微观尺度下对由裂尖氧化膜和基体金属共同构成的应力腐蚀裂尖应力应变场进行了分析。结果表明,SCC裂尖氧化膜前端沟形裂纹的存在,会造成氧化膜中应力和应变的很大变化,且随着沟形裂纹的长度增加,这种变化越加明显;另一方面,与氧化膜中应力相比,塑性应变对裂尖形貌变化更加敏感,从一个侧面说明,裂尖塑性应变是研究SCC裂尖氧化膜形成与破裂比较理想的力学参量。 相似文献
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碳酸盐硫化氢复杂环境中16MnR钢应力腐蚀敏感性研究 总被引:1,自引:0,他引:1
采用慢应变速率拉伸试验研究了16MnR钢在碳酸盐和硫化氢复杂环境中的应力腐蚀开裂敏感性.结果表明,在含碳酸盐和硫化氢的复杂介质环境中,16MnR钢的应力腐蚀敏感性指数低于25%;温度由常温升高至57.5℃时,16MnR钢母材与热影响区的应力腐蚀敏感性略有升高,碳酸盐和硫化氢浓度对16MnR钢在此复杂环境中的应力腐蚀敏感... 相似文献
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Hong-Liang Ming Zhi-Ming Zhang Peng-Yuan Xiu Jian-Qiu Wang En-Hou Han Wei Ke Ming-Xing Su 《金属学报(英文版)》2016,29(9):848
Austenitic stainless steels are usually chosen to make many components of nuclear power plants(NPPs).However,their microstructure in the heat-affected zone(HAZ)will change during the welding process.Some failures of the weld joints,mainly stress corrosion cracking(SCC),have been found to be located in the HAZ.In this research,the microstructure,micro-hardness,residual strain and SCC behavior at different locations of the 316L HAZ cut from a safeend dissimilar metal weld joint were studied.However,traditional optical microscope observation could not find any microstructural difference between the HAZ and the base metal,higher residual strain and micro-hardness,and higher fraction of random high-angle grain boundaries were found in the HAZ than in the base metal when studied by using electron back-scattering diffraction scanning and micro-hardness test.What’s more,the residual strain,the microhardness and the fraction of random grain boundaries decreased,while the fraction of coincidence site lattice grain boundaries increased with increasing the distance from the fusion boundary in 316L HAZ.Creviced bent beam test was applied to evaluate the SCC susceptibility at different locations of 316L HAZ and base metal.It was found that the HAZ had higher SCC susceptibility than the base metal and SCC resistance increased when increasing the distance from the fusion boundary in 316L HAZ. 相似文献
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The effect of hydrogen on the corrosion and stress corrosion cracking of the magnesium AZ91 alloy has been investigated in aqueous solutions.Hydrogen produced by corrosion in water diffuses into,and reacts with the Mg matrix to form hydride.Some of the hydrogen accumulates at hydride/Mg matrix(or secondary phase) interfaces as a consequence of slow hydride formation and the incompatibility of the hydride with the Mg matrix(or secondary phase),and combines to form molecular hydrogen.This leads to the development of a local pressure at the hydride/Mg matrix(or secondary phase)interface.The expansion stress caused by hydride formation and the local hydrogen pressure due to its accumulation result in brittle fracture of hydride.These two combined effects promote both the corrosion rate of the AZ91 alloy,and crack initiation and propagation even in the absence of an external load.Hydrogen absorption leads to a dramatic deterioration in the mechanical properties of the AZ91 alloy,indicating that hydrogen embrittlement is responsible for transgulanar stress corrosion cracking in aqueous solutions. 相似文献