共查询到19条相似文献,搜索用时 218 毫秒
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采用慢应变速率应力腐蚀方法研究喷砂处理对高速列车车体材料A7N01铝合金焊接接头应力腐蚀性能的影响。试验结果表明,经喷砂处理后,A7N01铝合金焊缝的残余拉应力转变为压应力,同时接头整体应力降低,趋于均匀分布。经喷砂处理后,A7N01铝合金焊接接头在3.5%NaCl中的应力腐蚀敏感指数降低,断口未呈现脆性断裂特征,表明喷砂处理增强了其抗应力腐蚀能力。喷砂试样表面均匀分布的压应力,降低了在外加载荷作用下焊缝所承受的拉应力,增加了焊接接头的强度。同时,表面压应力层的存在抑制了接头在腐蚀环境中裂纹的萌生,从而减少腐蚀介质向内部的扩散和作用,增强了焊接接头的抗应力腐蚀能力。 相似文献
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采用极化曲线方法研究了A7N01S-T5型铝合金在某系列的不同pH值清洗剂中的点蚀行为。试验结果表明铝合金在该系列中性、酸性和碱性清洗剂中均会发生点蚀,而铝合金点蚀敏感性的大小与清洗剂的pH值有关,pH值主要通过影响铝合金表面氧化膜和腐蚀产物膜的稳定性来影响铝合金的耐点蚀性能。 相似文献
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通过循环极化确定纯Al和Al-7Zn-0.1Sn-0.015Ga (质量分数,%) 合金在3.5%NaCl溶液中的自腐蚀电位Ecorr、点蚀电位Epit、点蚀转变电位Eptp和保护电位Erp,并通过Al和铝合金在这些特征电位的点蚀形貌研究了它们的点蚀行为及点蚀扩展机理。结果表明:在点蚀电位时开始出现点蚀坑,随着电位升高点蚀坑迅速向横向和纵向扩展直至保护电位;纯Al的点蚀坑为窄而深的方形点蚀形貌,蚀坑内部为粗糙的结晶状结构,且表面出现明显的丝状腐蚀。Al-7Zn-0.1Sn-0.015Ga合金的点蚀形貌为宽而浅的圆形腐蚀坑,蚀坑内部比较光滑,且丝状腐蚀消失。合金元素能明显活化合金,降低点蚀坑深度,改善其腐蚀形貌。 相似文献
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《中国有色金属学会会刊》2016,(3)
采用氯化钠+过氧化氢溶液浸泡试验研究AA6061-T6铝合金搅拌摩擦焊搭接接头的腐蚀行为。采用循环动电位极化测试、扫描电子显微镜和能谱仪表征腐蚀形貌,揭示焊接区与基体合金的腐蚀机理。研究了焊接接头的显微组织和剪切强度。结果表明,与基体合金相比,焊接区在腐蚀溶液中会发生晶间腐蚀和点蚀。搭接剪切测试结果表明,所得焊接接头的拉伸剪切强度为128 MPa,超过基体合金强度的60%。电化学测试结果表明,焊核区和热影响区的保护电位比点蚀电位更负,说明焊核区与热影响区点蚀的趋势不强。基体合金抗腐蚀性比焊缝区的强,而热影响区的抗腐蚀性最差。点蚀主要源于金属间化合物边缘,因为与铝基体相比,金属间化合物的自腐蚀电位更高而成为阴极。由于焊缝区的金属间化合物增加,腐蚀电偶增加,焊缝的抗腐蚀性降低。 相似文献
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力学化学效应对LY12CZ铝合金点蚀行为的影响 总被引:3,自引:0,他引:3
利用电化学测量技术研究了加载弹性载荷对LY12CZ铝合金在3%NaCI溶液中的自腐蚀电位、点蚀电位和保护电位的影响规律,同时利用小孔发展速率(PPR)-电位曲线法和电位扫描技术及显微测量技术研究了载荷对预选电位下的真实小孔发展速率的影响,根据点蚀电流密度随应力变化情况来研究力学化学作用对LY12CZ点蚀敏感性的影响,结果表明在加载应力时,LY12CZ铝合金的自腐蚀电位、保护电位和破裂电位都有不同程度的负移,负移的量取决于应力的大小。在加载应力时点蚀电流密度随应力增加也出现增大的现象,研究结果表明力学化学效应对LY12CZ铝合金的点蚀行为有显著影响。 相似文献
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研究静载荷对LY12CZ铝合金在3%NaCl水溶液中点蚀萌生、扩展的影响.当施加载荷时,LY12CZ合金的环状阳极极化曲线中的点蚀电位和保护电位都有一定程度的负移,表明外加载荷增大了点蚀敏感性,缩短了点蚀萌生期.在点蚀扩展阶段,点蚀的深度扩展与腐蚀时间之间符合幂函数的规律,与外加应力之间符合指数函数的关系. 相似文献
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Surface treatments of high alloy 6 Mo stainless steel and nickel alloy weldments High alloy stainless steels (6% Mo) and a high nickel alloy (alloy 625) weldment have been tested in order to answer the question whether post-treatment of the weldment has an effect on the corrosion resistance, especially on pitting corrosion. Therefore, the critical pitting temperature of weldments was tested in acidic chloride solution (standard tests). As a result grinding with rough emery paper as well as sand blasting lowers the localized corrosion resistance in the weldment area, while pickling has a positive effect, especially after blasting. Pickling can be done either by a solution of nitric + hydrofluoric acid or by a commercial pickling paste. In any event pickling is recommended as a final surface treatment for high alloy stainless steels and nickel alloys, especially in case of prevailing highly corrosive conditions such as pitting and crevice corrosion. 相似文献
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Effects of surface preparation on pitting resistance, residual stress, and stress corrosion cracking in austenitic stainless steels 总被引:1,自引:0,他引:1
A. Ben Rhouma H. Sidhom C. Braham J. Lédion M. E. Fitzpatrick 《Journal of Materials Engineering and Performance》2001,10(5):507-514
Surface finishing treatments such as shot blasting and wire brushing can be beneficial in improving the integrity of machined
surfaces of austenitic stainless steels. These operations optimize in-service properties such as resistance to pitting corrosion
and stress corrosion cracking (SCC). In this study, ground steel surfaces were subjected to a series of sand blasting and
wire brushing treatments. The surfaces were then characterized by their hardness, surface residual stress state, and resistance
to stress corrosion and pitting corrosion. Some samples were selected for depth profiling of residual stress. It is found
that surface hardening and the generation of near-surface compressive residual stress are the benefits that can be introduced
by sand blasting and brushing operations. 相似文献
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With superhydrophobic properties being extended to a variety of metallic substrates through the process of ablation due to femtosecond laser surface processing (FLSP), it is important to understand corrosion behaviour of such a processed material. The material was tested through the use of an accelerated corrosion fog chamber using both treated and untreated aluminium alloy samples. During the accelerated corrosion testing, the FLSP-treated sample suffered from pitting corrosion at a rate faster than the untreated sample, effectively removing the surface treatment. While there are significant hydrodynamic benefits to this material, the elevated corrosion rates raise concerns about the resiliency of this surface treatment. 相似文献
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Enhancement of Corrosion Resistance of Type 304 Stainless Steel Through a Novel Thermo-mechanical Surface Treatment 总被引:1,自引:0,他引:1
Anita Toppo R. Kaul M. G. Pujar U. Kamachi Mudali L. M. Kukreja 《Journal of Materials Engineering and Performance》2013,22(2):632-639
The paper describes a novel thermo-mechanical surface treatment approach, involving conventional shot blasting followed by laser surface heating, to engineer microstructural modification in type 304 austenitic stainless steel for enhancing its corrosion resistance. Thermo-mechanical surface treatment resulted in the formation of fine recrystallized grains with some strain-induced martensite on the modified surface. Surface treatment of type 304 stainless steel brought about significant improvement in its resistance against uniform as well as pitting corrosion. Electrochemical impedance spectroscopic studies showed improved polarization resistance (R p) value for thermo-mechanically treated surface indicating formation of a more protective passive film than that formed on the untreated surface. In contrast to untreated type 304 stainless steel specimens where pits preferentially initiated at the site of Al2O3 inclusions, thermo-mechanically treated specimen exhibited only general dissolution with a few repassivated and shallow pits. Grain refinement and dispersion of alumina inclusions on the modified surface are considered to be the key factors responsible for improvement in uniform and pitting corrosion resistance of type 304SS. 相似文献
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目的提高2024-T3铝合金在中性Na Cl溶液中的耐小孔腐蚀性能。方法采用动电位极化曲线测试、扫描电镜(SEM)观察并结合X射线光电子能谱(XPS)等方法,研究2024-T3铝合金在含不同浓度Na2Sn O3的0.1 mol/L Na Cl溶液中的电化学腐蚀行为,分析Na2Sn O3及其浓度对2024-T3铝合金小孔腐蚀和均匀腐蚀的作用。结果电化学测试结果显示,添加一定量(0.05~0.4 g/L)的Na2Sn O3可以使溶液的p H值升高(可从6.6上升至10.1),促进铝合金表面发生钝化,使铝合金孔蚀电位Eb和自腐蚀电位Ecorr的差值增大(最大可达到600 m V),因此降低了铝合金的孔蚀敏感性,提高了其耐小孔腐蚀的能力。但是Na2Sn O3质量浓度较大(0.2、0.4 g/L)时,会促进2024-T3铝合金的均匀腐蚀。SEM和XPS结果显示,小孔及其附近区域Cu含量较多,并有大量的Sn O2颗粒沉积。结论少量(0.05、0.1 g/L)的Na2Sn O3对2024-T3铝合金的小孔腐蚀和均匀腐蚀均具有较好的抑制效果。Na2Sn O3对2024-T3铝合金的缓蚀作用可能源于其水解产生的Sn O2优先在铝合金表面的金属间颗粒(S相)周围发生沉淀,从而屏蔽了铝合金表面的活性点。 相似文献
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The heat affected zone (HAZ) on the metal–inert gas (MIG) welding joint of 7N01 aluminium alloy was repaired by multipass narrow gap laser welding. The Y–X direction precracked three‐point bending sample was used in the alternate immersion test. The morphology of specimen surfaces demonstrated that the exfoliation corrosion in the HAZ after laser repair (HAZa) was more serious than that before laser repair (HAZb). The electrochemical impedance spectroscopy after different immersion corrosion time indicated that the HAZa and HAZb had similar corrosion potentials. However, the pitting corrosion resistance of HAZa was lower than that of HAZb at the beginning of exfoliation corrosion. The stress corrosion crack (SCC) of 7N01P‐T4 aluminium alloy displayed a multicrack source and an intergranular crack propagated along the rolling grain boundary under the test condition. An unusual method was taken to measure the length of SCC. The results showed that laser repairing did not weaken the stress corrosion resistance of the original joint. 相似文献
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Omar Hatamleh Preet M. Singh Hamid Garmestani 《Journal of Materials Engineering and Performance》2009,18(4):406-413
The surface treatment techniques of laser and shot peening were used to investigate their effect on stress corrosion cracking
(SCC) in friction stir welded (FSW) 2195 aluminum alloy joints. The investigation consisted of two parts: the first part explored
the peening effects on slow strain rate testing (SSRT) in a 3.5% NaCl solution, while the second part investigated the effects
of peening on corrosion while submerged in a 3.5% NaCl solution with no external loads applied. For the SSRT, the laser-peened
samples demonstrated superior properties to the other samples, but no signs of corrosion pitting or SCC were evident on any
of the samples. For the second part of the study, the FSW plates were inspected periodically for signs of corrosion. After
60 days there were signs of corrosion pitting, but no stress corrosion cracking was noticed in any of the peened and unpeened
samples. 相似文献
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李嘉荣董建民韩梅刘世忠 《金属学报》2023,(9):1201-1208
将标准热处理的试样分别采用粒径为150、124和100μm白刚玉砂在0.5 MPa压力下吹砂,研究吹砂对第二代单晶高温合金DD6表面完整性的影响;对未吹砂和粒径150μm吹砂试样分别进行760和980℃旋转弯曲高周疲劳性能测试,研究吹砂对DD6合金疲劳性能的影响。结果表明:吹砂会破坏单晶高温合金的表面完整性,使表面出现砂粒切削造成的不规则凹坑,改变表面形貌;砂粒粒径增加,表面粗糙度和显微硬度均增大;吹砂使大量位错在γ相通道中滑移,靠近表面区域位错密度较大;并且,大量位错剪切γ’相,形成反相畴界和层错;吹砂造成形变强化、引入残余应力;150μm、0.5 MPa吹砂对DD6合金760℃旋转弯曲疲劳性能基本无影响,但会降低合金980℃疲劳性能,对低应力幅区疲劳寿命影响较大,使疲劳强度下降约7.3%。缺口效应、氧化损伤、形变强化和残余压应力的耦合作用导致吹砂与不吹砂试样疲劳寿命产生差异。 相似文献
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TiNi及Co合金生物医用材料的腐蚀行为及血液相容性 总被引:5,自引:0,他引:5
采用线性极化技术测量了生物医用材料TiNi形状记忆合金, CoCrNiMo和CoCrNiW的腐蚀速率, 并用动态电位扫描法考察了其阳极极化行为. 结果表明, 3种合金钝化电位区宽, 维钝电流密度小, 显示出优异的耐全面腐蚀性能. 电位扫描曲线滞后环面积及腐蚀后扫描电镜观察显示, 两种钴合金具有良好的耐孔蚀性能, 而TiNi的孔蚀倾向较大, 这是因为在TiNi合金表面夹杂的Ti2Ni易受活性阴离子的浸蚀, 而钴合金中的Co, Cr, Mo和W均易在表面形成钝性氧化膜, 抑制孔蚀的发生. 接触角、动态凝血时间和溶血率的测定表明TiNi具有更优的血液相容性, 这可能与其表面的TiO2膜具有较小的表面张力有关. 相似文献