不锈钢在含有溴离子的醋酸溶液中的腐蚀

采用浸泡试验及电化学试验,对304、254 SMO和HastelloyC－276三种材料在醋酸和含有Br^-离子的醋酸溶液中的腐蚀行为进行了测试。用SEM和XPS分析点蚀形貌。结果发现材料表面所形成的钝化膜中含有Cr2O3和MoO2,对材料起保护作用。     

NaCl溶液的浓度和温度对254SMO和2205不锈钢抗点蚀性的影响

用恒电位法和动电位法研究了254SMO不锈钢和2205双相不锈钢在50 g/L,100 g/L和200g/LNaCl溶液中的临界点蚀温度(CPT)和再钝化温度(CPrT),并绘制了两种材料在不同浓度溶液中的点蚀电位Epit和再钝化电位Eprot随温度的变化图,发现浓度越大,突变区域变缓变宽,材料CPT下降,耐蚀性下降....     

哈氏合金C22合金钢

正C22(N06022)哈氏(Hastelloy)合金,材料编号2.6402,是一种以镍、钼、钴、钨等元素组成的镍基高温合金,含镍量约为60%。是一种全能的镍铬钼钨合金,比其他的现有的镍铬钼合金拥有更好的总体抗腐蚀性能,包括Hastelloy C-276、C4合金以及625合金。Hastelloy C22合金有很好的抗点蚀,缝隙腐蚀和应力腐蚀     

高Mo超级奥氏体不锈钢和Ni-Cr-Mo镍基合金析出相研究及对比

选择典型牌号654SMO和C-276,对高Mo超级奥氏体不锈钢和Ni-Cr-Mo镍基合金的析出相进行研究,对不同时效条件下654SMO和C-276进行组织观察、EDS及相分析。结果表明,虽然654SMO和C-276均含有较高的Cr、Mo含量,但由于合金体系不同,其析出相种类形态各异,主要研究结果有:(1)654SMO有8种第二相析出,分别为:σ相、Cr_2N、μ相、χ相、Laves相、M_(23)C_6、M_6C和M_3C;(2)654SMO钢的主要有害析出相为σ相、Cr_2N,其析出相的析出峰值温度为900℃;(3)C-276合金的主要析出相是M_6C与μ相,在本研究时效条件下,并未出现σ相析出。     

Hastelloy C-276/316L激光异质焊焊缝腐蚀性能

利用连续激光对Hastelloy C-276和316L进行焊接,借助电化学腐蚀方法比较焊缝中心附近和母材在酸性、中性、碱性溶液中的腐蚀性能,并利用扫描电子显微镜和X线能量色散谱分析腐蚀形貌以及腐蚀表面元素成分。结果表明:在酸性环境中,抗腐蚀性由大到小的顺序为C-276的抗腐蚀性、焊缝、316L;在中性环境中,焊缝的抗腐蚀性和母材的相似;而在碱性环境中,焊缝的抗蚀性优于316L的,而其腐蚀趋势大于C-276的,但腐蚀速率小于C-276的;C-276中Mo元素较316L中的多,认为焊缝中Mo元素主要来自C-276,而Mo元素在焊缝枝晶间、枝晶杆的含量差别是造成焊缝在酸性、中性溶液中枝晶间腐蚀的重要原因之一;在碱性溶液中焊缝发生点蚀,这与晶格缺陷有关。     

不锈钢和镍基合金在含溴醋酸中的腐蚀行为

采用浸泡实验以及电化学实验,测试不同温度下的均匀腐蚀速率及不同温度、不同醋酸浓度、不同溴离子浓度下材料的孔蚀电位,研究不同因素对材料点蚀的影响,比较了１０种材料在含溴醋酸中的腐蚀行为。     

Hastelloy C-276合金应力松弛试验及蠕变本构方程

对Hastelloy C-276合金分别在不同的温度(750、800、850和900℃)和相应的初始应力(250、250、250和200 MPa)条件下进行了多组应力松弛试验。利用试验测得的应力松弛曲线推导出应力松弛过程中蠕变应变速率与应力之间的关系,建立用于描述Hastelloy C-276合金应力松弛行为的蠕变本构方程,通过对蠕变应变速率—应力曲线进行拟合,得到各温度下蠕变本构方程中的材料常数。将蠕变本构方程带入有限元软件MSC.Marc对Hastelloy C-276合金的应力松弛过程进行模拟,模拟得到的应力松弛曲线与试验测得的应力松弛曲线符合得很好,验证蠕变本构方程的可靠性。     

几种超级不锈钢在模拟低温多效海水淡化环境中的点蚀行为研究

在温度分别为20,40和70℃的2倍浓缩海水模拟溶液中,利用循环伏安曲线测试和SEM观察研究,对316不锈钢和超级不锈钢904L、254sMo以及2507的极化行为和表面点蚀形貌进行了研究。结果表明,在该环境中,升高温度可降低316、904L、254sMo和2507等4种不锈钢表面钝化膜的稳定性并提高其点蚀敏感性。在不同温度中,316不锈钢表面均发生严重点蚀损伤,而254sMo和2507不锈钢表面均无明显点蚀迹象。在低温时,904L不锈钢钝化膜击穿电位较高,点蚀坑尺寸较小,点蚀倾向较低;在高温时,其点蚀电位显著降低,点蚀坑尺寸明显增大,点蚀倾向较大。     

激光偏移量对Hastelloy C-276/316L焊缝腐蚀性能的影响

使用Nd:YAG连续激光对Hastelloy C-276/316L薄板进行异质焊接实验,分析不同激光偏移量下焊缝元素含量变化规律,借助极化曲线、电化学阻抗谱研究不同激光偏移量下焊缝在盐酸溶液中的抗蚀性能。结果表明:调节激光偏移量Fe、Ni和Mo含量变化明显,而Cr含量无明显变化;当激光向Hastelloy C-276偏移0.1~0.3 mm时,焊缝中主要元素含量变化较小,腐蚀电压、电荷转移电阻最大,腐蚀电流密度最小,焊缝腐蚀趋势、腐蚀速率最小,焊缝抗蚀性能较好;当激光向316L偏移0至0.2 mm时,焊缝中Fe元素逐渐增加,Ni、Mo元素含量逐渐下降,焊缝的腐蚀电压、电荷转移电阻递减,腐蚀电流密度递增,焊缝的腐蚀趋势、腐蚀速率逐渐增大,焊缝抗蚀性逐渐减弱。     

Hastelloy C-276合金应力松弛行为的研究

通过高温拉伸试验研究Hastelloy C-276合金在不同温度和初始应力下的应力松弛行为。实验得到了一系列应力松弛曲线,应用二次延迟函数对实验测得的应力松弛曲线进行拟合,拟合出的曲线与实验应力松弛曲线符合得较好。从实验测得的应力松弛曲线可以推导出不同温度下材料的蠕变应变速率与应力之间的关系,此外,还探讨了温度对Hastelloy C-276合金应力松弛的影响,为转子屏蔽套真空热胀形过程的有限元模拟工作奠定了理论基础,并为其提供了有价值的数据。     

Electrochemical behaviour of 254SMO stainless steel in comparison with 316L stainless steel and Hastelloy C276 in HCl media

Abstract

The electrochemical behaviour of 254SMO stainless steel in HCl solutions has been studied and compared with that observed for other alloys using open circuit potential measurements, potentiodynamic polarisation curves, and SEM analysis techniques. 254SMO does not display pitting corrosion at room temperature in HCl solutions having concentrations ≤5·0M. Its performance is comparable with that of Hastelloy C276 in HCl media in solutions of strength ≤1·0M. The critical pitting temperature for 254SMO exceeds 76°C in 3M HCl solutions.     

哈氏合金C276在溴胶混合液中的耐蚀性

目的研究哈氏合金C-276在溴胶溶液中的耐蚀性能,分析哈氏合金C-276在溴胶溶液中的腐蚀及失效机理。方法采用挂片试验方法,模拟溴化丁基橡胶生产过程中溴胶混合釜的腐蚀环境,研究温度、液溴含量、水含量、转速等环境因素影响哈氏合金C-276的腐蚀规律,利用SEM、XRD等现代分析技术,对腐蚀产物形貌、成分进行分析。结果哈氏合金C-276在含溴腐蚀溶液中的主要腐蚀产物为Ni Br2、Fe Br2、Mo Br2、Cr Br3等,腐蚀速率随温度、水含量、液溴含量以及转速的增加而增大。温度、水、液溴以及转速等因素均对腐蚀的发生起到了重要作用,腐蚀类型以全面腐蚀为主,伴随晶间腐蚀。结论溴胶混合液腐蚀环境下,哈氏合金C-276发生了严重的电化学腐蚀,提高温度、液溴含量、水含量、转速均会明显增加哈氏合金C-276的腐蚀速率。哈氏合金C-276不能作为溴化丁基橡胶生产设备中溴胶混合器的主材质。     

Zu einem Phänomen der Lochkorrosionsbegrenzung bei hochlegierten Sonderedelstählen und NiCrMo-Legierungen in Chloridlösungen

On a phenomenon of the limitation of pitting corrosion at high alloyed special stainless steels and NiCrMo-alloys in chloride solutions Testing the pitting corrosion resistance of high alloyed special stainless steels and NiCrMo-alloys in chloride solutions there was observed a limitation of the pitting corrosion range toward more positive potentials. Above this limitation, the so-called pitting corrosion limitation potential, the pit initiation by all means is prevented, but the growth of pits which had been initiated before in the pitting corrosion range not necessarily comes to a stop. Therefore current density-potential curves which are obtained by downward polarization after an initial potential jump into the transpassive region and chronopotentiostatic tests are more suitable to investigate this phenomenon than cyclic polarization measurements and potentiostatic alteration tests. There is indicated a dependence of this phenomenon on temperature. The phenomenon of a limitation of the pitting corrosion range toward more positive potentials has been found until now at alloy 926, alloy 31, alloy 28, alloy 59 and alloy C-276.     

The pit initiation mechanism on passive iron under both open-circuit and controlled potential conditions

The pit initiation mechanism on passive iron has been studied under open-circuit conditions and under anodic and cathodic polarization. In each case, an indispensable condition for pit initiation is that the passive film is thinned before pitting occurs, and at the most weak points on the passive film arises pitting. Under open-circuit conditions and under cathodic polarization, the pitting potential is determined by a coupling of the cathodic reduction of the passive film and the anodic dissolution of bare iron. The induction time for pit initiation under anodic polarization conditions is the period necessary for the passive film to reduce to a minimum thickness. The probable process for this is that the chloride ion detaches the iron ion from the passive film to form a chloride-iron complex ion.     

Critical pitting temperature for Type 254 SMO stainless steel in chloride solutions

The variation with time of the open circuit potential of high molybdenum containing stainless steel (Type 254 SMO) was measured in 4% sodium chloride solution in the temperatures range 30-100 °C. The plot of steady state potentials as function of temperature showed an inflection at 50 °C, attributed to the decrease of oxygen solubility in test solution above 50 °C. Potentiodynamic cycling anodic polarization technique was used to determine the critical pitting potential (E_pit) and the critical protection potential (E_prot) of the steel in 4-30% NaCl solutions at temperatures between 30 and 100 °C. By plotting the two values versus solution temperature, the corresponding critical pitting (CPT) and the critical protection (CPrT) temperatures were determined. Both parameters decreased with increasing chloride content. Above the CPT, E_pit and E_prot decreased linearly with log[Cl⁻]. The addition of bromide ions to the solution shifted both E_pit and E_prot towards positive values. In 4% NaCl, E_pit increased linearly with pH in the range 1-10. The combined effect of chloride ion concentration and pH on the morphology of the pits was examined by scanning electron microscopy (SEM) following potentiodynamic cycling anodic polarization.     

C-276合金650 ℃下持久抗力的显微分析

利用SEM和TEM,对固溶强化合金Hastelloy C-276的初始组织和在650 ℃、不同拉应力下持久断裂试样进行显微组织分析。结果表明：试样的断口以典型的韧窝形貌为主,局部有少许晶间断裂现象,显示出C-276合金具有良好的高温韧性。在C-276合金的初始组织中,有退火孪晶和大量位错存在;在经受高应力拉伸过程中,晶体内产生大量形变孪晶;同时,发现在晶界和晶内有细小弥散的析出物。因此,C-276合金在650 ℃下优越的高温持久抗力是固溶强化、沉淀强化以及可能的孪晶强化综合作用的结果。     

非晶合金Zr55Al10Cu30Ni5在3.5%NaCl溶液中的电化学行为

利用电化学极化曲线方法和电化学阻抗（EIS）技术研究了非晶合金Zr55Al10Cu30Ni5在3.5%NaCl溶液中的电化学行为。极化曲线测试结果表明，非晶合金Zr55Al10Cu30Ni5在3.5%NaCl溶液中具有很好的耐蚀性能，阳极过程表现出钝化特征，当极化电位很高时，非晶合金出现了点腐蚀。电化学交流阻抗测试表明，在阴极极化，开路电位和钝化电位下，非晶合金的Nyquist图由单容抗构成，具有很高的电荷转移电阻，表现出优良的耐蚀性，在点蚀电位附近和点蚀电位区EIS分别有两个时间常数和三个时间常数，非晶合金在3.5%NaCl溶液中浸泡12h后，耐蚀性能有所下降。