NaCl+HCl溶液中Ce对双相不锈钢腐蚀行为的影响

为了研究酸性NaCl溶液中双相不锈钢的耐腐蚀性能,以含微量稀土Ce的UNS S31803双相不锈钢为研究对象,采用电化学阳极极化和交流阻抗相结合的方法测试其在NaCl+HCl混合溶液中的耐腐蚀性能。利用扫描电镜(SEM)观测腐蚀后的形貌特征,采用电子探针(EPMA)检测合金元素与杂质元素的分布特征,分析Ce元素的加入对双相不锈钢电化学腐蚀行为的影响机制。结果表明,钢中存在两相的选择性腐蚀并伴有局部点蚀,其中铁素体相是腐蚀较严重的相;阳极极化测试与交流阻抗测试结果相吻合,Ce拓宽了试验钢的钝化区间;Ce通过净化钢液、降低S和P元素在相界的偏聚及使Cr、Ni和Mo等合金元素在两相中的分布更均匀等作用,提高了钢的耐腐蚀性能。     

PH13-8Mo不锈钢在半乡村大气环境中长周期腐蚀行为

在北京半乡村大气环境中对未经预钝化及硝酸预钝化后的PH13-8Mo不锈钢进行5 a的长周期暴晒试验,通过表面形貌观察、质量损失分析、表面钝化膜及腐蚀产物膜层分析、力学性能检测及断口分析等方法,研究了硝酸预钝化处理对PH13-8Mo长周期腐蚀行为的影响规律及机理。结果表明,经5 a大气暴晒试验,硝酸预钝化处理减轻了PH13-8Mo不锈钢的点蚀、降低其均匀腐蚀速率,通过降低PH13-8Mo不锈钢钝化膜中的氢氧化物含量、提高Cr/Fe原子比并提高大气暴晒后表面的Kelvin电位,延迟了Cl?对钝化膜的破坏及点蚀的形核,进而提高了表面膜层对基体的保护作用。硝酸预钝化处理能减少在半乡村大气环境中PH13-8Mo不锈钢力学性能的下降,但对试样的断裂方式几乎没有产生影响,二者均为韧性断裂,断口均呈现典型的“杯锥状”。      

外加拉应力对13Cr马氏体不锈钢的腐蚀行为影响

采用电化学测试手段(开路电位、交流阻抗谱及动电位极化曲线测试), 结合接触角测试及体视显微镜微观形貌观察探究在80 g·L-1 NaCl溶液中拉应力对L80-13Cr马氏体不锈钢钝化膜溶解与再修复机制的影响.结果表明, 拉应力大小与L80-13Cr的钝化特性存在正相关关系.随着外加拉应力的增大, L80-13Cr马氏体不锈钢的开路电位负移, 电子转移电阻减小, 线性极化电阻减小, 反应速率随着拉应力的增大而增大.而L80-13Cr马氏体不锈钢在高电位下再钝化形成的钝化区会缩短, 自腐蚀电位降低, 维钝电流密度增加.接触角测试和体视显微镜微观形貌观察发现, 拉应力使得表面接触角减小, 不锈钢表面容易发生点蚀.外加拉应力使得L80-13Cr马氏体不锈钢的表面能增加, 促进钝化膜的溶解, 并且抑制钝化膜的再生, 导致材料耐蚀性降低.      

Mn对2205双相不锈钢耐点蚀性能的影响

研究锰元素对2205双相不锈钢耐点蚀性能的影响, 锰质量分数的变化范围为0. 93%~1. 26%.分别采用化学腐蚀法、动电位极化法研究双相不锈钢2205的耐腐蚀性能, 采用夹杂物自动分析技术研究锰对钢中夹杂物种类及数量的影响, 通过扫描电镜、能谱及夹杂物原位分析法观察化学腐蚀及电化学腐蚀前后钢中夹杂物及其周围钢基体的变化情况.采用电感耦合等离子体发光光谱测定腐蚀产物的成分.研究结果表明, 不同类型的夹杂物对耐腐蚀性能的影响不同, (Mn、Si) 氧化物以及(Mn、Si、Cr) 氧硫化物在腐蚀液中更易溶解进而促进腐蚀, 而(Cr、Mn、Al) 氧化物却很稳定.锰的加入会促进钢中(Cr、Mn、Al) 夹杂的析出, 此类夹杂物不仅自身很容易被含Cl离子的溶液腐蚀, 而且作为点蚀的起始点, 促进了点蚀坑的形成, 加快了基体腐蚀, 最终导致不锈钢耐点蚀性能的下降.      

Corrosion Behavior of TiC Particle‐Reinforced 2Cr13 Stainless Steel

The corrosion behavior of TiC particle‐reinforced 2Cr13 stainless steels prepared by in situ reaction and electroslag remelting (ESR) was investigated using potentiodynamic polarisation measurements and immersion tests. The addition of TiC particles to 2Cr13 stainless steel impeded rapid pit propagation but maintained a high corrosion rate in the whole immersion time investigated. The TiC addition developed finer matrix structure, the formation of Cr‐rich carbides and high dislocation density around the TiC particles before corrosion, which results in an increasing corrosion rate and preferential pitting attack at the steel matrix/TiC interface. Although the corrosion resistance of 2Cr13 stainless steel is sharply decreased due to TiC addition, it is significantly improved after the ESR process. This is attributed to the more uniform distribution and smaller size of TiC particles, the increase of value of χ in TiCχ and the elimination of the porosity in TiC particle‐reinforced 2Cr13 stainless steel after the ESR process.     

Studies on Nb Microalloying of 13Cr Super Martensitic Stainless Steel

The effect of Nb microalloying on microstructure, mechanical properties, and pitting corrosion properties of quenched and tempered 13?pct Cr-5?pct Ni-0.02?pct C martensitic stainless steels with different Mo and N contents was investigated. The microstructure, density, and dispersion of high-angle boundaries, nanoscale precipitates, and amount of retained austenite were characterized by using electron backscattered diffraction, transmission electron microscopy, and X-ray diffraction to correlate with properties. The results show that the combined effects of lowering nitrogen content in 13?pct Cr-5?pct Ni-1~2?pct Mo-0.02?pct C steels to 0.01?wt pct, and adding 0.1?pct Nb are to decrease the amount of Cr-rich precipitates, as Nb preferentially combines with residual carbon and nitrogen to form carbonitrides, suppressing the formation of Cr₂N and Cr₂₃C₆. Austenite grain refinement can be achieved by Nb microalloying through proper heat treatment. If the nitrogen content is kept high, then Cr-rich precipitates would occur irrespective of microalloying addition. The NbN would also occur at high temperature, which will act as substrate for nucleation of coarse precipitates during subsequent tempering, impairing the toughness of the steel. It was shown that the addition of Nb to low interstitial super martensitic stainless steel retards the formation of reversed austenite and results in the formation of nanoscale precipitates (5 to 15?nm), which contribute to a significant increase in strength. More importantly, the pitting corrosion resistance was found to increase with Nb addition. This is attributed to suppression of Cr-rich precipitates, which can cause local depletion of Cr in the matrix and the initiation of pitting corrosion.     

硅对含强氧化性离子沸腾硝酸中奥氏体不锈钢耐蚀性的影响

 超低碳Cr Ni奥氏体不锈钢在含强氧化性离子的硝酸溶液中会发生过钝化腐蚀和晶间腐蚀,而高硅不锈钢在强氧化性浓硝酸中具有优良的耐蚀性。笔者以高纯级000Cr25Ni20和00Cr14Ni14Si4钢作为对比材料,发现在纯稀硝酸中000Cr25Ni20钢具有更优良的耐蚀性,在不同含量的40%沸腾硝酸溶液中,00Cr14Ni14Si4钢可有效抑制过钝化腐蚀,而且不发生晶间腐蚀。     

硫酸介质中铸造奥氏体不锈钢的腐蚀磨损行为

研究了几种铸造奥氏体不锈钢在含有Ｃｌ－的硫酸介质中的点蚀规律,测定了腐蚀磨损率、摩擦因数和表面钝化膜破坏后的修复时间。实验结果表明,高铬、镍、铜不锈钢有较高的耐蚀性,但其腐蚀磨损失重却高于一般的１８－８型不锈钢     

超级13Cr在H2S和CO2共存环境下的腐蚀行为影响研究

对CO2和H2S共存环境中95 ksi钢级超级13Cr钢的腐蚀行为进行了研究,发现常温条件下H2S和CO2共存环境中,无论是采用恒载荷的方法还是四点弯曲的方法,都在试样的表面出现了局部腐蚀,而在高温条件下未发生点蚀和应力腐蚀现象。分析结果表明,95 ksi钢级的超级马氏体不锈钢在常温H2S和CO2共存环境中出现的局部腐蚀主要是因为夹杂物在应力集中和酸性溶液的作用下形成点蚀,并沿着相同应力水平的区域扩展,局部腐蚀增加了应力腐蚀开裂的敏感性。     

Corrosion resistance of high-strength austenitic chromium–nickel–manganese steel containing nitrogen

The corrosion resistance of high-strength Cr–Ni–Mn austenitic steel containing nitrogen and copper is compared with that of Cr18Ni9 and Cr18Ni10N chromonickel steel by means of the Zive MP2 electrochemical system. The polarization curves and electrochemical characteristics of the alloys are determined in general, pitting, and intercrystallite corrosion by various media: aqueous solutions of NaCl (3%); FeCl₃ 6H₂O (100 g/L); H₂SO₄ (0.5 M); H₂SO₄ (0.5 M) + injected H₂S; and H₂SO₄ (0.5 M) + KSCN (0.01 M). The corrosion rates are calculated. The results indicate that all the steel samples are corrosion-resistant: they exhibit high resistance to intercrystallite corrosion and also to pitting and general corrosion in chloride-bearing media. No pitting corrosion is observed when Cr–Ni–Mn steel of balanced composition containing nitrogen (and especially steel containing both nitrogen and copper) is immersed in sea water, even when the steel’s nickel content is low. This steel outperforms traditional Cr18Ni9 steel in terms of strength and corrosion resistance, even in an acidic medium (0.5 M H₂SO₄).     

445J2超纯铁素体不锈钢和316L超低碳奥氏体不锈钢在溴化锂溶液的点蚀分析

445J2铁素体不锈钢由于高的导热率、低的热膨胀系数以及良好的耐蚀性能使得其作为溴冷机中一些部件的良好候选材料,本文采用电化学测试方法对比研究了445J2超纯铁素体不锈钢(/%:0.01C,22.5Cr, 1.9Mo, 0.27Nb, 0.20Ti, 0.09Al, 0.36Cu, 0.015P,0.001S,0.015N)和316L奥氏体不锈钢(/%:0.002C,16.8Cr, 10.19Ni, 2.02Mo, 0.025P,0.0008S)在20～60℃0.1～1M的溴化锂溶液中的点蚀行为,并采用扫描电镜(SEM)和能谱分析仪(EDS)对电化学结果进行表征。结果表明,随着LiBr温度和浓度的升高,两种钢腐蚀电流密度增大,点蚀电位降低,耐点蚀性变差;氧化物和硫化物夹杂会引起两种钢的点蚀;高含量的Cr以及Mo、Ti、Nb、Al等合金元素使445J2钢具有优异的耐点蚀性能。     

Effects of Cu Content on Inclusions and Pitting Corrosion in S32205 Duplex Stainless Steel

Cu is an austenite-forming element in duplex stainless steel, and the precipitation of Cu-rich phase can improve the strength of the alloy. However, the role of Cu element in the corrosion resistance of stainless steel is widely controversial. Herein, the effects of different Cu content on the formation of inclusions and the pitting resistance of duplex stainless steel are studied by using potentiodynamic anodic polarization test, immersion corrosion, scanning electron microscope, and electron probe microanalysis. The results show that the pitting potential decreases significantly with the increase of Cu content, which greatly reduces its ability to resist Cl⁻ corrosion. The reason is that Cu increases the driving force for the formation of Al-containing oxides, which increases the number and size of Al-containing inclusions formed in the process of melting and solidification. At the same time, Cu promotes the formation of Cr-depleted zone, which promotes the formation of microcracks and pitting corrosion between steel matrix and inclusions in duplex stainless steel.     

氮对316LN奥氏体不锈钢力学性能和耐蚀性的影响

试验用316LN钢(/%:0.015C、0.65Si、0.90Mn、17.3Cr、12.8 Ni、2.6Mo、0.018~0.200N)由50 kg真空感应炉冶炼,破真空后加入氮化铬铁,铸锭锻成Φ20 mm棒材和热轧成4 mm板材,并分别经1 100℃30 min和10min水淬固溶处理。研究结果表明,316LN不锈钢每增加0.010%的氮,抗拉强度提高9 MPa,屈服强度提高7 MPa;伸长率降低0.55%,氮含量对断面收缩率没有影响,约保持在72.5%;氮强烈提高316LN不锈钢的耐点腐蚀性能,每增加0.010%的氮,其点蚀击穿电位提高7 mV;添加适宜的氮(0.079%N),可以改善316LN不锈钢的耐晶间腐蚀性能,过高的氮含量(超过0.120%N)对晶间腐蚀性能有害。     

非金属夹杂物对不锈钢耐点蚀性能影响的综述

摘要：首先,总结了3种常用的非金属夹杂物对不锈钢耐点蚀性能影响的研究方法,即原位腐蚀观察、微区电化学法、原子力显微镜。其次,总结了硫化物、氧化物、稀土夹杂物3种不同类型夹杂物对不锈钢耐腐蚀性能影响。随着硫化物含量的增多,不锈钢的耐点蚀性能会下降;对于氧化物的影响,目前的研究集中在氧化物的成分对不锈钢耐点蚀性能的影响。不同成分的夹杂物对不锈钢耐点蚀性能的影响机制还不是很清楚;稀土夹杂物对不锈钢点蚀的影响主要与稀土对不锈钢中夹杂物改性有关。而后,汇总了目前提出的夹杂物对不锈钢耐点蚀性能影响的机制,即贫Cr区机制、微缝隙机制、活性机制。贫Cr区机制主要用于解释硫化物引起的点蚀,后2种主要用于解释氧化物引起的点蚀。最后,提出了夹杂物控制提升不锈钢耐点蚀性能的展望。     

时效处理对00Crl3Ni7Co5Mo4W马氏体时效不锈钢组织及耐蚀性的影响

采用动电位极化曲线、均匀腐蚀全浸试验研究了50 kg真空感应炉冶炼的00Cr13Ni7Co5Mo4W马氏体时效不锈钢（/%:0.007C,13.23Cr,7.02 Ni,5.06Co,3.72Mo,0.96W）1100℃1 h固溶,450510℃8 h时效后的耐蚀性能,通过金相显微镜、透射电镜、XRD分析了马氏体时效不锈钢的组织。结果表明,随时效温度升高时效过程析出R相增加,导致钢的耐点腐蚀性下降,同时由马氏体逆转变的奥氏体数量增加,可改善该钢的耐腐蚀性能。00Cr13Ni7Co5Mo4W马氏体时效不锈钢适宜的热处理工艺为1100℃1 h固溶+470℃8 h时效,其年腐蚀速率为1.259 0 μm/a,点蚀击穿电位为252 mV。     

Corrosion Resistance and Semiconducting Properties of Passive Films Formed on 00Cr13Ni5Mo2 Supermartensitic Stainless Steel in Cl- Environment

The semiconducting properties of passive films grown on 00Crl3Ni5Mo2 supermartensitic stainless steel were investigated in comparison with conventional 2Cr13 martensitic stainless steel. Cyclic vohammetry and electro- chemical impedance spectroscopy （EIS） were used for the studies. 00Crl3NiSMo2 steel exhibited a good corrosion resistance performance, attributing to its passive capability. The results of Mott-Schottky analysis demonstrated n- type semiconductors for the passive films with doping densities of about 1020- 1021 cm -3, and the thickness of space- charge layers was also calculated. The experimental results confirmed that Mo plays an important role in improving the corrosion resistance of 00Crl3Ni5Mo2 steel due to its impact on the doping density.     

高温高压环境下不同浓度KBr溶液对13Cr不锈钢的腐蚀行为影响

油气工业中溴盐完井液的使用极易导致油套管腐蚀失效的发生, 尤其是局部腐蚀风险.针对这一问题, 采用高温高压腐蚀模拟试验、扫描电镜观察与分析、电化学测试等试验研究方法, 研究了高温高压环境下不同浓度溴盐溶液对普通13Cr和超级13Cr两种典型油套管材腐蚀行为的影响.结果表明: 从平均腐蚀速率来看, 两种13Cr管材在三种浓度溴盐溶液中均表现出较好的耐蚀性能, 属于轻度或中度腐蚀, 但从局部腐蚀速率来看, 两种材料均达到严重或极严重腐蚀; 随着溴盐浓度的提高, 普通13Cr的自腐蚀电位和点蚀电位均明显负移, 对应材料的平均腐蚀速率和局部腐蚀速率均明显上升, 而超级13Cr仅点蚀电位明显负移, 自腐蚀电位则相对稳定, 对应其平均腐蚀速率变化幅度较小, 局部腐蚀速率则明显上升, 这说明相比普通13Cr, 超级13Cr对溴盐溶液具有更强的整体耐受能力, 但局部腐蚀敏感性仍然较高; 激光共聚焦(LSCM)三维表征结果表明, 在高质量浓度溴盐溶液(1.40 g·cm-3)中, 不论是普通13Cr还是超级13Cr都有明显的点蚀倾向, 这主要与溶液中高浓度的侵蚀性阴离子Br-有关, 相比于普通13Cr, 超级13Cr的点蚀敏感性相对较低, 但其点蚀风险仍不可忽视.      

幕墙连接件用铸态中氮奥氏体不锈钢的力学性能和耐蚀性

试验用新型铸态超低碳低镍中氮奥氏体不锈钢022Cr20Mn10Ni6N(%:0.023～0.027C、9.86～9.95Mn、19.24～20.09Cr、5.41～5.42Ni、0.27～0.34N)由15 kg中频感应炉冶炼,并试验研究了铸态022Cr20Mn10Ni6N钢与铸态304钢(%:0.076C、1.87Mn、18.02Cr、8.64Ni)的组织,力学性能和耐蚀性。结果表明,新型铸态不锈钢的力学性能、耐点蚀性能、耐弱酸弱碱均匀腐蚀性能明显优于铸态304不锈钢,新型铸态不锈钢022Cr20Mn10Ni6N中性盐雾耐蚀性和304钢相当,可满足大气环境玻璃幕墙金属连接件的应用要求。     

Pitting Corrosion Behavior of Stainless Steel 304 in Carbon Dioxide Environments

The pitting corrosion behavior of stainless steel (SS) 304 in aqueous CO2-H2S-CI-environment was investigated by potentiodynamic cyclic anodic polarization and electron probemicroanalysis (EPMA). The experimental results show that the pitting corrosion susceptivityof SS 304 increases with the increase of temperature. Chlorine ion is the prerequisite for pittingcorrosion of SS 304 in H2S-CO2 environments. There is a linear relatiotxship between the pittingcorrosion potential (Eb-100) and chlorine ion concentration, and Eb-00 becomes noble with in-creasing pH value of the solution with or without H2S. pH value has little effect on the protec-tion potential with the presence of Hz S. H2S increases strongly the pitting corrosion susceptivi-ty and deteriorates the pitting corrosion resistance of SS 304 in CO2 environments. The obser-vations by EPMA show that SS 304 in CO2-saturated NaCI solution (3%) with H2S sufferspitting corrosion accompanied with intergranular corrosion.     

445M铁素体不锈钢缝隙腐蚀性能的研究

研究了445M铁素体不锈钢(%:0.004～0.005C、22.24～22.29Cr、1.10～1.65Mo、0.015～0.016P、0.003～0.004S、0.012～0.016N、0.22～0.38Ti)和316L奥氏体不锈钢(%:0.022C、16.80Cr、10.19Ni、2.02Mo、0.025P、0.001S、0.046N)在40～60℃氯离子浓度(250～5 000)×10^-6的氯化钠溶液的缝隙腐蚀性能。结果表明,445M铁素体不锈钢的耐缝隙腐蚀性能优于316L奥氏体不锈钢;当445M钢中的Mo含量由1.10%提高至1.65%时,钢的耐缝隙腐蚀性能明显提高,表明点蚀当量Cr+3.3Mo是衡量不锈钢耐点蚀和耐缝隙腐蚀的重要指标。