共查询到16条相似文献,搜索用时 140 毫秒
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为了研究17-7PH不锈钢在海洋大气环境下接触腐蚀的防护问题,将不同表面状态的17-7PH不锈钢板状试样在青岛团岛和海南万宁进行1年的大气暴晒试验,对其宏观腐蚀形貌对比,并测定其疲劳寿命,采用扫描电子显微镜(SEM)观察暴晒试样表面腐蚀形貌,用光学显微镜比较腐蚀坑深度,分析海洋大气腐蚀对17-7PH不锈钢疲劳性能的影响,最后得出了17-7PH不锈钢的腐蚀防护措施。结果表明:在青岛暴晒的不涂漆17-7PH不锈钢试样表面色泽变暗,有均匀的细小点蚀,而海南的试样表面有大面积较均匀的褐色锈层,特别是17-7PH不锈钢与TC18钛合金连接处腐蚀较为集中,但腐蚀并没有降低其疲劳寿命;从暴晒试样的表面微观腐蚀形貌比较,无论涂漆与否,17-7PH不锈钢表面都有轻微腐蚀,但只局限于表层,点蚀不深,并且趋向均匀腐蚀;17-7PH不锈钢抗大气腐蚀性能很好,经钝化后可不涂漆直接在海洋大气环境中使用1年,而不会对其疲劳性能产生明显影响。 相似文献
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316L不锈钢为常用的耐蚀合金材料,然而其在海洋大气环境服役时易遭受点腐蚀而发生失效。通过点腐蚀速率、临界点蚀温度、点蚀电位、极化曲线测试等评价方法,对经过不同表面处理(光亮退火、抛光、酸洗钝化)后的316L不锈钢的耐点蚀性能进行测试分析。结果表明,不同表面处理对316L不锈钢的临界点蚀温度影响不大,但会使点腐蚀速率、点蚀电位有所差异;在测试条件下,抛光及酸洗钝化均可有效提高316L不锈钢的耐点蚀性能,其中酸洗钝化态的耐点蚀性能最好,因此建议对海洋工程用316L不锈钢产品在使用前进行酸洗钝化处理。 相似文献
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研究了17—4PH不锈钢的金属注射成形工艺及其流变学性能、力学性能、微观组织和耐腐蚀性能。结果表明:采用65%PW-30%EVA-5%SA粘结剂组成的注射料具有最好的综合流变学性能。在1380℃保温90min的烧结条件下,注射成形17—4PH不锈钢的力学性能最佳,孔隙分布均匀,晶粒尺寸适中。而保温60和120min则分别表现出烧结不完全和过烧现象。1380℃保温90min烧结所得到的力学性能为P=7.70g/cm^3,σb=1275MPa,δ=5%,硬度36HRC。注射成形17—4PH不锈钢的密度、抗拉强度、硬度随着烧结温度的升高而提高,伸长率则随着烧结温度的升高而下降。17—4PH不锈钢的耐蚀性好,腐蚀期长,具有活化-化金属极化曲线的特征,但钝化电位范围较窄,耐点蚀性能较差。 相似文献
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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”。 相似文献
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《不锈(市场与信息)》2010,(14):3-4
不锈钢的表面因形成致密的氧化铬薄膜而具有高抗腐蚀能力,得以广泛应用于现代工业领域以及日常生活。然而,在抗均匀腐蚀的同时,不锈钢的局部点状腐蚀(即“点蚀”)却难以避免。点蚀的发生起始于材料表面,且经过形成与长大两个阶段,最终向材料表面以下的纵深方向迅速扩展。因此,点蚀破坏具有极大的隐蔽性和突发性。 相似文献
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采用扫描电镜、能谱、电化学阻抗谱和拉曼光谱等分析测试手段,研究了西沙群岛苛刻海洋大气环境下,经过不同时间暴露后304不锈钢的腐蚀行为和机理.304不锈钢在西沙大气暴露后的腐蚀类型主要是以局部腐蚀的点蚀为主,腐蚀产物主要由β-FeOOH、γ-Fe2O3和Fe3O4组成.随暴露时间的延长,不锈钢表面钝化膜的稳定性变差,点蚀数目增加、点蚀坑深度增大日.表面腐蚀产物覆盖率也逐渐增多.与其他部位相比,点蚀更容易在表面划痕处产生.提高表面加工精度,有助于提高其耐腐蚀性能. 相似文献
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利用磁致伸缩空蚀试验机对Cr32Ni7Mo3N特级双相不锈钢在蒸馏水和人工海水中进行了空蚀实验,并采用扫描电镜跟踪观察了经不同时间段空蚀后试样的形貌.通过测量失重绘制了材料的累积失重量和失重率曲线.经电化学工作站测量了材料在静态与空蚀条件下的极化曲线和腐蚀电位变化.对比分析了Cr32Ni7Mo3N与SAF2205双相不锈钢在人工海水的抗空蚀能力.结果表明:Cr32Ni7Mo3N特级双相不锈钢空蚀破坏首先在铁素体薄弱区以及铁素体和奥氏体相界发生,并向铁素体内扩展,铁素体发生解离断裂脱落;奥氏体随着空蚀的进行,滑移线增多,显微硬度值增加,且人工海水中奥氏体显微硬度值比在蒸馏水中的高;铁素体大面积破坏后,奥氏体才失稳产生延性断裂脱落,奥氏体的存在延缓了破坏在整个材料表面上的扩展.空蚀与腐蚀交互影响导致材料在人工海水中加速破坏.Cr32Ni7Mo3N特级双相不锈钢在人工海水中的抗空蚀能力优于SAF2205双相不锈钢. 相似文献
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This study investigates the effect of plasma nitriding parameters on corrosion susceptibility of 17-4 PH stainless steel in 3.5?wt-% NaCl solution. In this regard, 17-4 PH stainless steel was plasma nitrided at 400°C for 5 and 10?h, 450°C for 5?h and 500°C for 5?h. Cross-sectional images after nitriding process showed that a uniform nitrided layer has been formed on steel substrate. Depending on the temperature and time of the nitriding process, different phases were formed in the nitrided layer. This affected general corrosion and pitting corrosion performance of 17-4 PH stainless steel in 3.5?wt-% NaCl solution. While precipitation of chromium nitrides for nitrided specimens at 450°C and higher increased the susceptibility to pitting and general corrosion, formation of expanded martensite (EM) in nitriding at 400°C improved the pitting corrosion resistance of 17-4 PH stainless steel. This is believed to be due to the release of nitrogen atoms from EM phase to form ammonium ions and increase the pH of the solution, supressing pit growth. 相似文献
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LI Ping CAI Qi-zhou WEI Bo-kang ZHANG Xian-zhong 《钢铁研究学报(英文版)》2006,13(5):73-78
The effect of aging temperature on erosion corrosion (E-C) behavior of 17-4PH stainless steels in dilute sulphuric acid slurry containing solid particles was studied by using self-made rotating E-C apparatus. The effect of impact velocity on EC behavior of 17 4PH steels at different aging temperatures was analyzed. Surface micrographs of the specimens after E C test were observed by using scanning electron microscope (SEM). The results showed that under the condition of the same solution heat treatment, when aging temperature ranged from 400 ℃ to 610℃, the hardness reached the highest value near the temperature 460℃. The characteristics of E-C for 17-4PH stainless steels at different aging temperatures were as follows: pure erosion (wear) was dominant, corrosion was subordinate and at the same time corrosion promoted erosion. The effect of aging temperature on E-C rate of 17-4PH steels was not significant at low impact velocity, but it was found that E-C resistance of 17-4PH steels aged near 460℃ was the most excellent due to the best precipitation strengthening effect of fine and dispersed e-Cu phase. With a prerequisite of appropriate corrosion resistance, the precipitation hardening could significantly improve the E-C resistance of the materials. 相似文献
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不锈钢是推动现代工业发展的关键金属材料之一。在重载、盐雾、空化、高温等恶劣工作环境下,不锈钢材料存在耐磨损、耐腐蚀、抗空蚀、抗高温氧化等表面性能不足的问题,限制了其更为广泛的应用。激光熔覆技术是近年发展较为迅速的绿色表面改性技术,其熔覆层具有组织致密且均匀、晶粒细小、膜基结合强等优点,已被广泛应用于不锈钢表面强化领域。对影响熔覆层质量的关键工艺参数与送料方式进行研究,归纳熔覆层表面强化研究现状,总结激光熔覆技术的工业应用和新型激光熔覆复合技术,进而对激光熔覆技术发展趋势及应用前景进行展望。 相似文献
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In order to improve surface hardness and corrosion resistant property of 17-4PH martensitic stainless steel, the steel was plasma nitrocarburized at 560 °C for 2-24 h in a gas mixture of nitrogen, hydrogen and ethanol with rare earths (RE) addition. The experimental results showed that the modified layer was characterized by a compound layer containing two distinct zones (i.e. out ’dark zone’ and inner ’white zone’). The inner ’white zone’ was almost a precipitation free zone and had high hardness as well as good corrosion resistance. Anodic polarization test results showed that the specimens plasma nitrocarburized with RE addition had good corrosion resistance resulted mainly from their higher corrosion potentials, lower corrosion current densities and larger passive regions as compared with those of the untreated one. 相似文献