1000 MPa级冷轧双相钢的热处理工艺与性能研究

从高强度冷轧双相钢的冶金成分设计出发,设计了三种不同成分的C-Mn-Si系冷轧双相钢,通过在(α γ)两相区不同温度的加热淬火,获得(Ferrite Martensite)双相组织;探讨了1000 MPa级冷轧双相钢的热处理工艺、性能与组织;研究了退火温度、冷却速度对双相钢性能的影响,分析了双相钢的强化机理,并且优化了退火工艺参数.结果表明,1000MPa级冷轧双相钢最优退火温度为780～800℃,680℃开始快冷,缓冷速度为10℃/s.     

双相钢在流动3.5aCl溶液中的磨损腐蚀

研究了０Ｃｒ２５Ｎｉ６Ｍｏ３Ｃｕ双相钢在流动３．５ＮａＣｌ溶液中的磨损腐蚀行为,并对其磨损腐蚀的动力学过程进行了探讨。结果发现;双相钢在流动３．５％ＮａＣｌ溶液中的磨损腐蚀速度随着流速的增大而增大,并存在一个使磨损座 刀剧上升的临界值,随阒温度的升高,其磨损腐蚀明显加重。     

采油管材N80钢在流动介质中的腐蚀行为研究

采用循环流动腐蚀试验装置，研究了N80钢在模拟油田含氧流动介质中的腐蚀行为，分析比较了温度、流速等因素的影响。结果表明，在流动的含氧模拟油田采出液中，N80钢的腐蚀速度因溶液温度不同而异，30℃时，随流速提高，腐蚀速度加快，而当温度升到40℃以后，随流速提高腐蚀速度反而下降。     

L80钢的H2S腐蚀行为及H2S缓蚀剂的性能

通过高温高压动态反应釜研究了温度、H₂S分压、流速对L80钢H₂S腐蚀行为的影响，对腐蚀产物进行SEM和EDS元素分析，优选了耐高温的H₂S缓蚀剂LH-11,并对其缓蚀性能进行研究。结果表明：L80钢的H₂S腐蚀速率在80℃达到最大值，在140℃达到最小值；L80钢的腐蚀速率随H₂S分压的升高而增大，随流速的增大逐渐增大，腐蚀产物主要为硫铁化合物，结构疏松不规则，且有孔隙。缓蚀剂LH-11对L80钢的缓蚀率可达到87.05%,耐温180℃;添加缓蚀剂后，L80钢的腐蚀速率可降至0.1 mm/a以内，该缓蚀剂适用于不同H₂S分压和不同流速条件，可对热采管柱起到较好的保护作用。     

热处理工艺对2205双相不锈钢耐蚀性能的影响

对2205双相不锈钢采用不同温度进行热处理,然后用光学显微镜和电子扫描电镜观察其在0.33mol/L FeCl3+0.05 mol/L HCl溶液中腐蚀后的形貌;测试其显微硬度的变化、在沸腾的65%的硝酸溶液中浸蚀24 h的腐蚀速率和在25℃的3.5%NaCl溶液中的点蚀电位。研究表明:2205双相不锈钢在750~900℃保温4h有σ相析出,材料的显微硬度增大。同时随着热处理温度的升高,2205双相不锈钢的点蚀电位降低,腐蚀速率增大。     

金属在流动氯化物体系中流动腐蚀的EIS研究

流动氯化物体系中碳钢、双相钢电极的电化学阻抗谱（EIS）明显不同,随着流速增大,电极表面受到的切应力增大,反应阻抗减小,电化学腐蚀加速,协同效应增强,结果使电极流动腐蚀速度增加,与碳钢相比,双相钢电极在较高流速下其电化学阻抗谱才在低频区发生特征变化,证明了曹楚南提出的不可逆电极阻抗谱理论同样适用于流动腐蚀过程中电极过程的研究,揭示了在流动体系中,当电极表面受到足够大的切应力作用时,在低频区电极电化学阻抗谱会发生特征改变,其中,电化学阻抗谱的低频感抗弧特征预示着在流动腐蚀过程中,受到强力流体力学作用的电极表面会改变其常规的溶解速度和溶解机制,同时表面伴随有坑、点局部腐蚀的发生,在此情况下,钝态金属电极的电化学阻抗谱进一步反映了电极表面受到固体颗粒摩擦或撞击的阻抗谱特征。     

碳钢在液/固双相管流中磨损腐蚀的电化学行为

利用自行研制的管流动态模拟试验装置，研究了碳钢在液／固双相流中的磨损腐蚀．结果表明：碳钢在含有5％河砂的双相流动3．5％NaCl溶液中。磨损腐蚀速度随流速的增加而显著增大。没有像单相流中出现磨损腐蚀速度显著降低的流速区段，其磨损腐蚀过程仍主要受阴极氧扩散控制．对碳钢施加阴极电流，由于抑制了腐蚀电化学因素，从而大幅度削弱了与流体力学因素间的协同效应，使碳钢的磨损腐蚀大大减轻。     

连续退火工艺和合金元素对800 MPa级冷轧双相钢组织性能的影响

在实验室试制了800MPa级别的高强度低成本C-Mn-Si系双相钢,研究了双相钢的双相处理工艺、组织和性能.通过对三种不同成分的双相钢在( γ)两相区的加热淬火处理获得了不同比例的F M双相钢钢板,其性能可通过调整双相处理工艺来确定.结果表明,800 MPa级冷轧双相钢最优加热温度为760～800℃,缓冷速度为10℃/s.     

铁素体/奥氏体双相钢在旋转单相流体中腐蚀的数值模拟

引入现代流体力学方法，建立流体力学、传质过程、腐蚀电化学反应的综合数学模型，对双相钢在流动3．5％NaCl水溶液的腐蚀过程进行了数值模拟．探讨了近壁处流体力学参数对双相钢腐蚀过程的作用，模拟结果表明：双相钢的腐蚀主要受阳极过程控制，其中钝化膜中的传质过程是腐蚀的主要控制步骤．计算的腐蚀速度与实测值基本一致,验证双相钢的流体腐蚀机构．     

不同冷却速度下建筑双相钢组织及性能变化

研究高强度建筑双相钢在不同冷却速度下的组织及性能变化。首先确定试样的临界冷却速度,然后将试样升温至800℃,保温后分别以10、20、30和40℃/s的速度冷却至350℃,观察各阶段试样金相组织,在万能试验机上测试不同冷却速度下试样的力学性能。结果表明,冷却速度为10℃/s时,双相钢中软基体体积分数大,抗拉强度和屈服强度都较低。随着冷却速度增大至20、30和40℃/s时,抗拉强度和屈服强度逐渐增大,但是变化范围不大。     

对相钢在流动中性含砂氯化物中的磨损腐蚀

研究了双相钢在流动含砂的3．5％NaCl溶液中的磨损腐蚀规律,测定、分析了流动体系中的电化学阻抗谱,揭示了双相钢磨损腐蚀过程中电化学的作用及其机制。结果表明,腐蚀曜 磨损腐蚀过程中起主要作用,流体力学因素只是加速了腐蚀电化学过程,阻抗谱在低频区出现一直线段和低频收缩现象。分别是双相钢在磨损腐蚀过程中电极处于自钝化状态,并受离子在钝化膜中的扩散、迁移过程控制和电极表面局部遭受破坏的特征,对于流动体系中电化学阻抗谱的分析,曹氏阻抗理论同样适用。     

新型海水管系材料HDR双相不锈钢的腐蚀和电化学性能

针对新型海水管系材料HDR双相不锈钢的研制和开发，通过冲刷腐蚀，砂侵蚀以及点蚀和缝隙腐蚀电化学试验，研究了其耐海水腐蚀性能和电化学性能，与TUP，B10，B30的耐蚀性能进行了对比，结果表明，HDR很耐流动海水冲刷腐蚀和砂侵蚀，耐点蚀，缝隙腐蚀性能良好，适合作为海水管系材料。     

Corrosion behaviour of highly alloyed stainless steels in mixed chloride and fluoride aqueous solutions

Laboratory weight loss and cyclic potentiodynamic polarization corrosion tests were performed on two types of corrosion resistant alloys, a duplex alloy (ferritic-austenitic stainless steel) and two austenitic stainless steels, in mixtures of chloride (3000, 9000 and 15000 ppm) and fluoride (4800 and 15000 ppm) ions at pH 3. Two temperatures were tested, 60 and 70°C. The electrochemical results indicate that the duplex stainless steel presents high corrosion resistance. Weight loss results show low corrosion rates of the two types of stainless steels after 60 days exposure. Sonic pits-crevices were found under the corrosion crust deposits on the duplex stainless steel.     

Influence of sigma-phase formation on the localized corrosion behavior of a duplex stainless steel

Because of their austenitic-ferritic microstructures, duplex stainless steels offer a good combination of mechanical and corrosion resistance properties. However, heat treatments can lower the mechanical strength of these stainless steels as well as render them susceptible to intergranular corrosion (IGC) and pitting corrosion. In this study, a low-carbon (0.02%) duplex stainless steel is subjected to various heat treatments at 450 to 950 °C for 30 min to 10 h. The heat-treated samples then undergo ASTM IGC and pitting corrosion tests, and the results are correlated with the microstructures obtained after each heat treatment. In the absence of Cr₂₃C₆ precipitation, σ-phase precipitates render this duplex stainless steel susceptible to IGC and pitting corrosion. Even submicroscopic σ-phase precipitates are deleterious for IGC resistance. Longer-duration heat treatments (at 750 to 850 °C) induce chromium diffusion to replenish the chromium-depleted regions around the σ-phase precipitates and improve IGC resistance; pitting resistance, however, is not fully restored. Various mechanisms of σ-phase formation are discussed to show that regions adjacent to σ-phase are depleted of chromium and molybdenum. The effect of chemical composition (pitting resistance equivalent) on the pitting resistance of various stainless steels is also noted.     

Corrosion behaviour of duplex stainless steels sintered in nitrogen

Duplex stainless steels obtained through powder metallurgy (PM) technology from austenitic AISI 316L and ferritic AISI 430L powders were mixed on different amounts to obtain biphasic structures with austenite/ferrite ratio of 50/50, 65/35 and 85/15. Prepared mixes of powders have been compacted at 750 MPa and sintered in N₂-H₂ (95% and 5%) at 1250 °C for 1 h. Corrosion behaviour, using electrochemical techniques such as anodic polarization measurement, cyclic anodic polarization scan and electrochemical potentio-kinetic reactivation test and double loop electrochemical potentio-kinetic reactivation double loop test were evaluated. For duplex stainless steels, when austenite/ferrite ratio increases the corrosion potential shifts to more noble potential and passive current density decreases. The beneficial effect of annealing solution heat treatment on corrosion behaviour was established and was compared with corrosion behaviour of vacuum sintered duplex stainless steels. The results were correlated with the microstructural features.     

高流速海水中金属材料的腐蚀行为

<正> 一、前言 金属材料在自然海水中的腐蚀数据通常是在自然海流(0.1～1米/秒)条件下获得的,但滨海的电站、石油、化工系统中的高流速管道、泵、热交换器、阀门以及高速舰船中的管道以至船体等,都处在较高流速(5～30米/秒)海水的环境中。因此,各国相继开展了高流速海水中金     

Selektive Korrosion von Duplexstahl. Teil 2: Lokale Korrosionserscheinungen an Duplexstahl X2CrNiMoN22‐5‐3 unter Einwirkung von Chloriden und mechanisches Verhalten in Abhängigkeit vom Gefügezustand

Selective corrosion of duplex stainless steel. Part 2: Localized corrosion manifestations under exposure of chlorides on duplex stainless steel X2CrNiMoN22‐5‐3 and mechanical behavior in dependence of the microstructure In completion to part 1 of this paper this part deals with interrelations between localized corrosion manifestations, mechanical properties and the microstructure of duplex stainless steel X2CrNiMoN22‐5‐3. The pit formation on duplex stainless steels is substantially determined by the distribution of the alloying elements within single phases and by defects in the oxide layer. The positive properties of molybdenum become ineffective at thicker oxide layers due to the fact, that molybdate, which is responsible for inhibition of pitting, can not be formed. Depletion areas caused by precipitations are preferential attack places for corrosion. The influence of chlorides for duplex stainless steels in rolled and welded conditions is characterized by a logarithmic dependence.     

热处理对双相不锈钢组织和腐蚀性能的影响

    研究了热处理温度和时效时间对双相不锈钢微观组织及腐蚀性能的影响,结果表明:随着固溶温度提高,双相钢中奥氏体含量增加.固溶温度为1060℃,铁素体含量大约在45%~50%之间,两相比例大约为1∶1,抗点蚀性最好.时效处理时间越长,双相不锈钢中σ相析出越多,其耐腐蚀性能越差.析出的σ相周围形成的贫铬区优先被腐蚀,降低了双相不锈钢抗点蚀性能.