1Cr13不锈钢的应力腐蚀开裂和应力腐蚀的缓蚀剂

研究了在酸性氯毁子溶液中抑制1Cr13不锈钢应力腐蚀开裂的缓蚀剂,研究表明这种不锈钢的应力腐蚀开裂受氢脆机理所控制,抑制应力腐蚀开裂的缓蚀剂均抑制了阴极过程,这是与奥氏体不锈钢的结果不同的,对于奥氏体不锈钢抑制应力腐蚀开裂的缓蚀剂均抑制了阳极过程     

不锈钢应力腐蚀开裂综述

应力腐蚀开裂一直以来是不锈钢领域的重要研究课题,也是许多行业亟需解决的工程问题。应力腐蚀开裂是材料、环境和应力三者相互作用的结果,由于其复杂性,目前人们对不锈钢发生应力腐蚀开裂的机理尚存在许多不同的见解,但是经过近一个世纪的研究,从材料选择、环境控制等方面入手,预防不锈钢发生应力腐蚀是能够达到的。综述了应力腐蚀开裂的特征、机理和三个影响因素(应力、材料和环境)。对应力腐蚀的阳极溶解机理和氢致开裂机理进行了概述,阐述并探讨了不锈钢应力腐蚀开裂的滑移溶解机理、氧化膜开裂机理以及氢致开裂机理。归纳了组织结构对不锈钢应力腐蚀的影响,分析了材料成分如(Ni、Mo和N)的添加与应力腐蚀敏感性的关系,总结了环境因素在应力腐蚀中的作用,对特定介质中不锈钢的应力腐蚀规律进行了归纳,并探讨了温度变化对不锈钢应力腐蚀的影响。介绍了近年来关于控制不锈钢应力腐蚀开裂方法的研究进展,如晶界工程、细化晶粒以及涂层等。最后展望了不锈钢应力腐蚀开裂未来的研究方向。     

双相不锈钢应力腐蚀行为及防护技术研究进展

双相不锈钢含有铁素体+奥氏体两相组织,具有良好的机械和腐蚀性能,尤其以出色的抗应力腐蚀开裂性能而著称。但双相不锈钢在特定的环境和拉应力共同作用下,会出现应力腐蚀开裂现象,由于应力腐蚀开裂通常难以被发现,从而导致灾难性的事故。在此基础上,从材质的成分和金相组织,温度、pH、氯离子和氧气浓度等工况环境,冷变形和残余应力等方面总结了影响双相不锈钢应力腐蚀开裂的因素。结合双相不锈钢的使用环境和应力特点,阐述了双相不锈钢的应力腐蚀开裂机理,包括电化学阳极溶解理论、氢脆机制、膜破裂理论、化学脆化一机械破裂两阶段理论、应力吸附破裂理论。依据应力腐蚀开裂机理,结合影响因素,通过合理添加合金元素开发出新的双相不锈钢、双相不锈钢等离子碳氮共渗或表面涂层、热处理工艺等方法,有效地降低双相不锈钢应力腐蚀开裂的敏感性。最后,从双相不锈钢应力腐蚀开裂机理和防护技术两方面展望了双相不锈钢应力腐蚀开裂未来的研究方向,从本质上减少应力腐蚀开裂事故的发生,保障生产的“安稳长满优”。     

氯化物溶液中敏化304不锈钢应力腐蚀开裂的临界电位

研究了氯化物浓度、溶液温度、应力及敏化程度对敏化304不锈钢在NaCI水溶液中晶间型应力腐蚀开裂的影响。结果表明，材料的敏化程度、NaCI浓度、溶液温度和应力对敏化304不锈钢的ER.SCC有显著的影响，敏化304不锈钢的DR．SCC低于ER．CREV，应力腐蚀开裂发生在正于ER．SCC的电位范围，而电位低于该值则免于发生应力腐蚀开裂，由此得知，ER．SCC可适用于评价敏化不锈钢的应力腐蚀开裂敏感性。     

奥氏体不锈钢管线开裂失效分析及预防措施

某石化公司一奥氏体不锈钢管线发生腐蚀开裂。本文通过宏观检验、化学成分分析、金相检验和硬度检验等方法进行失效原因分析,确定开裂原因为碱应力腐蚀开裂,并提出了建议措施。     

敏化态304不锈钢在室温下发生应力腐蚀的Cl~-浓度界限

用慢应变速率实验技术研究了敏化态304不锈钢在室温氯化钠溶液中的应力腐蚀行为。结果表明:敏化态304不锈钢在近中性的氯化物溶液中呈典型的沿晶应力腐蚀开裂,随Cl-浓度的提高,应力腐蚀开裂敏感性增强,应力腐蚀的发生存在一个临界Cl-浓度。关键词     

321不锈钢在蒸馏装置常压塔顶腐蚀行为分析

考察了蒸馏装置常压塔顶321不锈钢的腐蚀情况,通过对挂片进行断口分析、金相分析及电子探针微区分析,得出321不锈钢在常压塔的腐蚀破坏原因为应力腐蚀开裂,开裂类型为穿晶和沿晶的混合型开裂。     

不锈钢的腐蚀分析

分析了不锈钢应力腐蚀开裂(SCC),点腐蚀、晶间腐蚀,腐蚀疲劳,缝隙腐蚀,以及不锈钢的腐蚀机理。     

敏化态304不锈钢在室温下发生应力腐蚀的Cl~－浓度界限

用慢应变速率实验技术研究了敏化态３０４不锈钢在室温氯化钠溶液中的应力腐蚀行为。结果表明：敏化态３０４不锈钢在近中性的氯化物溶液中呈典型的沿晶应力腐蚀开裂，随Ｃｌ－浓度的提高，应力腐蚀开裂敏感性增强，应力腐蚀的发生存在一个临界Ｃｌ－浓度。关键词     

应用神经网络技术预测应力腐蚀开裂

利用已有的应力腐蚀开裂数据训练人工神经网络，对奥氏体不锈钢在含有氯离子和氧的溶液中的应力腐蚀开裂敏感性进行了预测。所用的网络结构为三层结构，氯离子和氧含量作为网络输入，腐蚀开裂敏感性作为输出。学习算法为反向传播算法，以预测精度作为标准，训练得到网络的优化结构为2-6-1。结果表明，该劂络对应力腐蚀的预测比较准确，用神经网络技术预测应力腐蚀开裂敏感性是可行的。     

Expansion stress analysis of ferroconcrete corrosion by digital reflection photoelasticity

This study used digital photoelastic birefringent coatings, to measure the expansion stress of a steel bar boundary with concrete caused by corrosion. The distribution of expansion stresses were measured in the initial cracking and partial cracking stages. A numerical model was used to estimate and compare the expansion stress generated by the steel bar during different corrosion and crack stages. The feasibility of applying digital image processing photoelasticity to long-term monitoring and measurement of steel bar corrosion and expansion stress was verified by the consistent results obtained.     

Stainless steel thread forming screws and their susceptibility to stress corrosion cracking

Abstract

Thread forming fasteners incorporate both drilling and hole tapping features and are commonly used in the construction industry to fix together steel sheets of different material types. With this practical application in mind, fasteners manufactured from martensitic and austenitic stainless steels have been subjected to alternating corrosion conditions in accordance with test standards DIN 50021-SS and DIN 50018-K WF 2·0. The torque applied to the screws during these tests was controlled to place the fasteners under equal tensile loads, independent of their tensile strength. Thus, the results provided information on their relative susceptibilities to stress corrosion cracking. At the end of the tests, up to 80% of the martensitic stainless steel drilling and tapping screws had failed due to hydrogen induced stress corrosion cracking. The fasteners manufactured from austenitic materials withstood identical test conditions without any evidence of cracking or crack initiation. It is concluded that fasteners manufactured from modified martensitic stainless steel are more susceptible to stress corrosion cracking under the conditions of test than those made from cold worked austenitic stainless steels. This suggests that in practical applications the potential for catastrophic failure due to stress corrosion cracking could be considerably higher in modified martensitic fasteners in comparison with austenitic stainless steel fasteners, including those with hardened carbon steel drill points.     

低合金高强度抗应力腐蚀开裂海洋软管用钢的开发

通过合金成分设计,轧制、热处理工艺的探索,开发了低合金高强度海洋软管用钢,其屈服强度大于600 MPa且满足抗氢脆、抗氢致开裂、抗应力腐蚀开裂性能,并通过全浸腐蚀实验对该钢的海水腐蚀行为进行了研究。结果表明,采用低C、低Mn并复合添加耐蚀元素Cr、Mo和采用合理的热轧、冷轧、调质处理工艺,可获得满足抗应力腐蚀开裂性能的600 MPa级高强钢。耐蚀元素的添加使实验钢具有良好的耐海水腐蚀能力,腐蚀稳定状态下的平均年腐蚀速率为0.11 mm/a。     

Einflüsse von Werkstoff und Verarbeitung auf die Spannungsrißkorrosion von Spannstählen

Influence of material and processing on stress corrosion cracking of prestressing steel In prestressed concrete constructions the highstrength prestressing steels perform essential bearing effects. The alkaline layer of concrete or mortar protects the steels against corrosion and guarantees a permanent load capacity. If the corrosion protection as a result of poor workmanship is not guaranteed from the beginning, or is lost because of lacks of construction in the course of time, or the steels are predamaged during handling, stress corrosion cracking and failure of steel and construction may occur. Also an application of unsuitable materials (prestressing steel, injection mortar, concrete) can alone or in combination with the before mentioned influences favour stress corrosion cracking. In the contribution the correlations and typical failures are discussed.     

Stress corrosion cracking initiation under the disbonded coating of pipeline steel in near-neutral pH environment

A novel test setup has been used in this study to simulate stress corrosion cracking initiation under a disbonded coating on an X-65 pipeline steel. In this setup, the synergistic effects of cyclic loading, cathodic protection and soil solution environment under disbonded coatings have been considered. When the X-65 pipeline steel was exposed to the test environment, there existed a wide range of corrosion products on the steel surface in the gradient of cathodic protection. Increasing the test time and the maximum stress increased the possibility of stress corrosion cracking initiation in regions with a high susceptibility to pitting corrosion.     

Korrosion niedrig legierter Stähle in flüssigem Ammoniak

Corrosion of low-alloyed steels in liquid ammonia Corrosion behaviour and stress corrosion cracking of the base material, the welding and the heat affected zone in liquid ammonia at room temperature of the low-alloyed steels 13 Cr Mo 4 4 (W. Nr. 1.7335) and 15 Mo 3 (W. Nr. 1.5415), as well as the un-alloyed steel StE 460 (W. Nr. 1.8905) for comparison were investigated. According to polarization curves, the corrosion current density in the passive state usually was lower for the welding than for the base steel. In the active state the welding of the low-alloyed steel corroded faster than the weldings of the unalloyed steel. In the region between the welding and the heat affected zone of the base steel corrosion was nonuniform. CERT-experiments revealed susceptibility to stress corrosion cracking in the orders StE 460 < 15 Mo 3 < 13 Cr Mo 4 4, and base steel < welding < transition zone. The highest susceptibility was observed at electrode potentials in the middle of the passive region. Additions of water exceeding about 100 ppm favoured stress corrosion cracking. The susceptibility decreased again at concentrations ≥ 1000 ppm. Oxygen increased the susceptibility to stress corrosion cracking only at high concentrations not occurring in practice. The presently investigated low-alloyed steels are not superior to the unalloyed steel from the viewpoint of stress corrosion cracking.     

X60螺旋缝埋弧焊管在湿H2S环境中的腐蚀行为

采用自行设计的焊管实物管段腐蚀试验方法和装置研究了内胀成形和外控成形两种X6 0螺旋缝埋弧焊管在含H2 S的NACE溶液中的腐蚀行为。结果表明 ,焊管在H2 S介质中的损伤表现为母材表面氢鼓泡及应力腐蚀裂纹 ;随着施加应力的提高及残余应力的增大 ,H2 S腐蚀倾向增大 ;在H2 S介质中和外加应力及残余应力的共同作用下 ,焊管的氢损伤机理既有氢致开裂 ,又有氢致应力腐蚀 ,应力不但促进氢致应力腐蚀 ,同时也促进氢致开裂过程 ;试验结果说明改进焊管焊缝表面质量、降低残余拉应力、控制工作应力是改善和控制焊管H2 S腐蚀的重要措施     

Untersuchungen zur Spannungsrißkorrosionsbeständigkeit nichtrostender Stähle mit unterschiedlichem Verformungsgrad

Investigations on stress corrosion cracking resistivity of stainless steels with different degree of cold straining Within the context of the elaboration of a new approval for stainless steels for civil engineering applications the question arised whether cold straining could adversely affect the resistance against stress corrosion cracking. By means of experimental tests with different stainless steels it should be clarified whether cold straining increase the stress corrosion cracking susceptibility under high chloride loads like e.g. in swimming hall atmospheres. The investigations were carried out using the high-alloyed steels 1.4462 and 1.4529. As reference material with known susceptibility against stress corrosion cracking the steel 1.4301 was used. The tests were performed using U-bent and tension specimens with saturated MgCl₂ salt spots. Indications for an increase in stress corrosion cracking susceptibility of the cold drawn steel were not found.     

2507双相不锈钢钾盐蒸发罐腐蚀的原因分析

以某院设计的两个项目中的蒸发罐实际使用情况为切入点,从2507双相不锈钢设备的使用环境和制作工艺两方面分析了钾盐蒸发罐发生腐蚀开裂现象的原因,进而讨论了如何在设计、制造及使用过程中避免双相不锈钢设备发生腐蚀。结果表明:双相不锈钢蒸发罐的使用环境和制造工艺均对其耐蚀性有很大的影响,尤其是当有焊接瑕疵和组装残余应力造成的应力集中,或在强酸、高温、高Cl~-含量介质溶液的环境中运行时,设备极易发生应力腐蚀裂纹。     

不同应力条件下不锈钢局部腐蚀行为的研究进展

不锈钢因具有良好的耐腐蚀性能而倍受重视,在众多工业领域内被广泛使用,但在实际应用中,由于受到腐蚀环境和应力的共同作用,不可避免地会产生点蚀或裂纹,导致服役性能下降,甚至引发各类安全事故.所以,应力条件下不锈钢的腐蚀行为一直是不锈钢材料腐蚀领域的重要研究课题.总结了部分代表性的不锈钢材料在应力作用下局部腐蚀行为的研究进展,主要总结与讨论了弹性应力、塑性应力以及残余应力对不锈钢点蚀及腐蚀开裂行为的影响规律.弹性应力如何影响不锈钢点蚀与腐蚀开裂还不是特别清楚,一般认为弹性拉应力会促进点蚀的萌生,使点蚀坑内产生应力集中,促进腐蚀扩展,但也发现了较小弹性拉应力会抑制点蚀的情况,而且机理也尚不明确,并且弹性压应力到底是促进还是抑制点蚀萌生也尚未达成一致.塑性应力对不锈钢局部腐蚀的影响机理已经比较明确,塑性应力会导致位错的产生,从而促进点蚀和裂纹的生长.残余拉应力会促进不锈钢点蚀和裂纹的生长,但残余压应力却能够有效抑制不锈钢点蚀和裂纹的生长.因此,在较低至中等弹性应力下的不锈钢局部腐蚀行为及其影响机理应该加强研究,而对于塑性应力与残余应力,则应该进一步深入探讨其作用下不锈钢局部腐蚀行为的各阶段特征和断裂临期特征,以期精确进行腐蚀断裂风险的评估和解决寿命评估的难题.