Ni-Cr-Mo耐蚀合金在CaCl_2-CaF_2熔盐中的腐蚀行为

通过全浸腐蚀实验,采用XRD,OM,SEM和EDS研究了Hastelloy C276和Hastelloy N合金在80%CaCl_2+20%CaF_2(质量分数)熔盐中的腐蚀行为.结果表明,Hastelloy C276和Hastelloy N合金均发生晶间腐蚀,其具体形式为Cr和Mo元素沿晶界发生选择性脱溶腐蚀.由于腐蚀层和腐蚀产物对元素扩散的阻碍作用,Hastelloy C276和Hastelloy N合金在熔盐中的腐蚀速率均逐渐减缓,其腐蚀失重C与腐蚀时间t符合C=Kt~n关系.     

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     

镍基耐蚀合金及其焊接特性概述

简述了镍基合金的分类及不同镍基合金的耐腐蚀能力,较深入地介绍了镍基耐蚀合金的焊接特点,包括在热影响区的敏化区间温度内有碳化物析出的可能,导致晶界出现贫铬,发生晶间腐蚀现象。电子探针分析发现,在焊缝树枝状晶粒内部,铬特别是钼含量大大减少;而在最后凝固的晶间区域,铬和钼元素却富集,所以在晶粒内部优先产生点腐蚀及其他腐蚀。文中还介绍了焊材的选用及焊接施工要点等,以便为镍基合金结构的制造提供技术支持。     

Hastelloy N合金表面激光熔覆NiCoCrAlY涂层在LiF-NaF-KF熔盐中的腐蚀行为研究

采用激光熔覆同步送粉技术在HastelloyN合金表面制备了NiCoCrAlY涂层,研究了HastelloyN基材和含NiCoCrAlY涂层的HastelloyN试样在900℃LiF-NaF-KF熔盐中的腐蚀行为。利用失重腐蚀法评估了试样的耐熔盐腐蚀能力,采用XRD和SEM表征了基材和涂层的物相组成、显微组织和腐蚀形貌,并结合EDS分析了微区成分。结果表明,NiCoCrAlY涂层试样的腐蚀速率仅为Hastelloy N基材的2/3。Hastelloy N基材表现为晶间腐蚀,其中Cr元素沿晶界发生选择性脱溶腐蚀,腐蚀前由γ-Ni和M_6C(M为Ni、Co、Cr等)等物相组成,腐蚀后新析出Co_9Mo_(21)Ni_(20)相。NiCoCrAlY涂层表现为均匀腐蚀,其中Al元素充当"消耗品"由涂层均匀向外扩散,形成的腐蚀产物可阻碍涂层中其它元素的扩散从而保护基材,腐蚀前主要由γ-Ni、Al_(0.983)Cr_(0.017)、AlNi_3等物相组成,腐蚀后只存在γ-Ni相。NiCoCrAlY涂层显著提高了基材的耐熔盐腐蚀性能。     

碳钢和铁-铬-镍基合金在相变储能材料用熔融共晶氯化钠和氯化镁中的腐蚀行为（英文）

研究了3种铁-铬-镍基合金(Fe-Cr-Ni)和一种碳钢试样在520℃熔融共晶NaCl-MgCl_2盐中的腐蚀行为。结果表明,碳钢试样晶界处Fe原子优先变为亚铁离子(Fe~(2+))和铁离子(Fe~(3+)),发生了严重的沿晶腐蚀,但表面形成了厚而致密的MgO壳,对试样起到了一定的保护作用。3种Fe-Cr-Ni基试样表面也形成了MgO壳,但因铬元素优先被腐蚀,试样表面形成了疏松的富Ni骨架状微观组织结构,MgO壳或颗粒极易剥落,未能起到有效的保护作用;Cr含量越高,腐蚀越严重。对于太阳能储能技术,在廉价的铁基合金中添加镍元素作为熔融氯化盐相变储热介质的容器或者管道材料,具有良好发展前景。     

碳钢和铁-铬-镍基合金在相变储能材料用熔融共晶氯化钠和氯化镁中的腐蚀行为

研究了3种铁-铬-镍基合金(Fe-Cr-Ni)和一种碳钢试样在520℃熔融共晶NaCl-MgCl2盐中的腐蚀行为。结果表明,碳钢试样晶界处Fe原子优先变为亚铁离子(Fe2+)和铁离子(Fe3+),发生了严重的沿晶腐蚀,但表面形成了厚而致密的MgO壳,对试样起到了一定的保护作用。3种Fe-Cr-Ni基试样表面也形成了MgO壳,但因铬元素优先被腐蚀,试样表面形成了疏松的富Ni骨架状微观组织结构,MgO壳或颗粒极易剥落,未能起到有效的保护作用;Cr含量越高,腐蚀越严重。对于太阳能储能技术,在廉价的铁基合金中添加镍元素作为熔融氯化盐相变储热介质的容器或者管道材料,具有良好发展前景。     

纯镍及镍基合金在真空熔融CaCl_2-20%CaF_2中的腐蚀行为

采用浸没腐蚀试验法分别研究了纯镍及Hastelloy C276合金在800℃真空熔融CaCl_2-20%CaF_2(质量分数)混合盐中的腐蚀行为。结果表明,两种试验材料的腐蚀质量损失均随时间的延长而增大,Hastelloy C276合金的腐蚀速率随时间逐渐减缓的程度明显大于纯镍。从腐蚀形貌和元素分布分析了试验材料在该环境中具有不同耐熔盐腐蚀性能的原因,并讨论了材料的腐蚀机理。     

γ-TiAl合金在高温熔盐环境下的腐蚀机理

在800℃、75%Na2SO4和25%NaCl的熔融盐环境中,对名义成分为Ti-48Al-2Cr-2Nb的γ-TiAl合金进行高温腐蚀实验。通过氧化动力学分析、扫描电镜观察及X射线衍射分析,研究全片层γ-TiAl合金的氧化腐蚀行为,以及高温腐蚀性环境对合金内部微观组织的选择性腐蚀机理。结果表明:在高温熔融盐腐蚀环境下,γ-TiAl合金主要形成由TiO2和Al2O3组成的氧化膜层,且高温熔融盐环境对合金内部微观组织存在明显的选择性腐蚀,即腐蚀路径沿α2与γ两相界面进入合金内部,并优先腐蚀α2相片层及γ相片层中的某些亚结构。合金片层组织中α2相与γ相间的抗氧化性能差异,以及熔融盐腐蚀性环境参与氧化中间反应并加速合金氧化过程是发生选择性腐蚀的主要原因。     

Hastelloy X和Haynes 230激光焊接头的组织性能

Hastelloy X和Haynes 230分别是F级和G/H级燃烧室薄壁筒体用的镍基高温合金,采用光纤激光器对2 mm厚度的两类镍基合金板材进行焊接试验,并对比焊态及焊后固溶处理的接头组织性能. 结果表明,焊态Hastelloy X的焊缝中碳化物呈网络状析出,其硬度高、韧性差,固溶处理后出现栅状组织及脆性Fe2W相. 在焊缝一次枝晶内的枝晶生长方向线性排列,取向各异,热影响区晶内也存在栅状组织. Haynes 230晶粒较小,焊缝碳化物沿树枝晶晶界链状断续析出,固溶处理后平直晶界变为弯曲晶界,蠕变性能得到提高.     

黄铜脱锌腐蚀行为特征的电子探针分析

黄铜脱锌作为一种选择性腐蚀现象给生产和生活带来很大的安全隐患.添加一些合金元素可以改善脱锌现象,改善黄铜的耐腐蚀性能.使用岛津电子探针EPMA测试了某种含锡的黄铜,表征了其脱锌腐蚀行为特征,以及添加的合金元素锡的分布特征及其在提高黄铜耐腐蚀性能方面的作用,即脱锌腐蚀首先发生在暴露于基体表面的β相晶粒,然后通过晶界和相界...     

Bildung und Einfluß von α'-Martensit auf die Spannungsrißkorrosion von Chrom-Nickel-Stählen

Formation of martensite and influence of the latter on stress corrosion cracking of chromium nickel steels Martensite formation depends from alloy composition, deformation and undercooling. By contrast to an industrial alloy corresponding to (DIN) X 10 CrNiTi189 a pure Fe 19 Cr 10 Ni alloy becomes partially martensitic upon deformation and quenching to ?190 °C. Undercooling and subsequent deformation give rise to the addition of deformation and quenching martensite. The formation of α′-martensite is largely suppressed by addition of 2% Mo. Since corrosion resistance in aqueous MgCl₂ solutions increases with the α′-martensite contents, cracks grow predominantly along the martensite plates. Addition of molybdenum reduces stress corrosion resistance because of the suppression of martensite formation. In this type of alloy cracking is intercrystalline nature.     

Spannungsrißkorrosion von hochlegierten Manganstählen in wäßrigen Chloridlösungen

Stress corrosion cracking of high alloy manganese steels in aqueous chlorides In tensile tests made without applied current in aerated solutions a stabilization of the austenitic structure by increasing Mn and N contents yields increased times to failure. The potential-time-to-failure curves determined by potentiostatic tensile tests reveal a compley joint action of constitution and passivation behaviour of the steels. The intercrystalline stress corrosion cracking of the steel X 40 MnCr 19 with chromium carbide precipitations at the grain boundaries can be attributed to an electrochemical differentiation of the chromium-depleted grain boundary region. Steels of this type are characterized by a pronounced sensitivity to intercrystalline stress corrosion cracking the precipitation annealed state, and by a certain sensitivity to transcrystalline corrosion cracking after solution annealing. Low carbon Mn steels containing up to 4 % Cr are susceptible to transcrystalline stress corrosion cracking irrespective of the heat treatment. As to the temperature dependence of times-to-failure, constitution and layer formation have different effects. Increasing the Cr content to 8 % gives rise to a transition from stress corrosion cracking to pitting type corrosion. In terms of electron optics, an increased chromium content gives rise to a changed dislocation pattern, so that there may be an effect of the type of gliding processes on stress corrosion, The increased stress corrosion resistance of MnCr steels containing at least 8% Cr may be due to the lower height Of the gliding step and to an increasing tendency to repassivation of damaged surface layers.     

利用双层辉光等离子技术进行镍基耐蚀合金表面合金化的研究

研究了在 2 0钢和不锈钢基材上 ,利用双层辉光离子渗金属技术进行Ni Cr Mo Cu多元共渗表面合金化 ,采用电化学方法对两种基材表面形成的渗层在 5 %HCl中的腐蚀性能进行了测定。结果表明 :在两种基材上都能得到类似于源极HastelloyC - 2 0 0 0合金的表面合金渗层 ,在不锈钢表面上形成的渗层的耐蚀性能接近HastelloyC - 2 0 0 0合金并且优于Alloy 5 9合金 ,在 2 0钢表面上形成的渗层耐蚀性能优于不锈钢Cr18Ni9     

Passivierungsverhalten und Spannungsrißkorrosion von Eisen-Mangan-Chrom-Legierungen in Natriumchlorid-Lösung

Passivation behaviour and stress corrosion cracking of iron-maganese-chromium alloys in sodium chloride solution Electrochemical experiments with MnCr steels (20–28% Mn, up to 12% Cr) in 3% NaCl solution. High Mn contents reduce the passivation tendency, while increasing Cr contents broaden the range of passivity. The formation of surface layers is due primarily to a direct reaction with the solution (good adhesion, high protective value) and, secondarily, to precipitation from the solution (porosity, low protective value). The tendency to form secondary layers increases as the Cr content is reduced. In oxygen containing solution there is a pronounced corrosion in the pitting range. At low Cr contents, stress corrosion cracking is mostly transcrystalline, at higher Cr contents (8–12%) it is intercrystalline, in particular when Cr carbide precipitations are present at the grain boundaries. In the range of transcrystalline corrosion the susceptibility to selective corrosion extends beyond the pitting potential. At higher Cr contents there may be pitting without any indication of stress corrosion cracking.     

Neue Erkenntnisse auf dem Gebiet der ferritischen rostfreien Stähle

Recent developments in ferritic stainless steels The pitting resistance of ferritic stainless steels in HCl is visibly improved by Mo, in particular in the case of vacuum-melted material. In this context the ratio Cr:Mo = 25:2 is superior ta Cr:Mo = 17:3; addition of Mo prevents, beyond that, crevice corrosion. Ti increases resistance in the Strauß test but not in the Huey test, while Nb turns out to have a positive effect in either test. Steels containing Cr: Mo = 17:l are certainly still susceptible to pitting, but no longer to stress corrosion cracking in boiling MgCl₂, solution; stress corrosion cracking is not observed in 55% boiling Ca(NO₃)₂, and 25% boiling NaOH, but after annealing at 980 °C intercrystalline corrosion takes place. The test duration required for establishing cracking susceptibility is considerably shorter with ferritic than with austenitic steels (100 and 1000 to 2000 hours respectively).     

Effect of Cr, Yb and Zr additions on localized corrosion of Al–Zn–Mg–Cu alloy

The effect of Cr, Yb and Zr additions on localized corrosion of Al–Zn–Mg–Cu alloy has been investigated. Additions of Cr, Yb and Zr to Al–Zn–Mg–Cu alloy stabilized the deformation-recovery microstructure with low angle grain boundaries on which grain boundary precipitates distributed discretely. The exfoliation and stress corrosion cracking of Al–Zn–Mg–Cu alloys propagated along the high angle recrystallized grain boundaries. The unrecrystallized Al–Zn–Mg–Cu–Zr–Cr–Yb alloy exhibited higher resistance to stress corrosion cracking and exfoliation corrosion, compared to the partial recrystallized Al–Zn–Mg–Cu–Zr alloy with high angle grain boundaries.     

选区激光熔化成形Hastelloy X合金持久性能研究

通过对选区激光熔化成形Hastelloy X合金持久试样进行组织性能与断口分析,研究Hastelloy X合金持久断裂模式及影响持久性能的主要因素,并对选区激光熔化成形与后处理过程进行组织演变规律追踪。分析认为,选区激光熔化成形Hastelloy X合金持久断裂模式为微孔聚合型沿晶韧窝断裂,碳化物的形态与数量、晶粒形态和取向是影响持久性能的主要因素。晶界薄膜状和较大颗粒状碳化物主要产生在热处理与热等静压冷却阶段,后续将调整后处理过程冷却速率,在碳化物析出峰附近快速冷却,控制碳化物形态与数量以有效提升Hastelloy X合金持久性能。     

哈氏C-2000合金在等温氧化时第二相沉淀析出行为

研究了哈氏C2000合金在800℃100h空气中等温氧化后合金基体中第二相的沉淀行为。氧化后基体中析出了富Mo相,可确定该富Mo相为具有金刚石结构的Mo3Ni3C型碳化物。富Mo相沿晶界和晶内分别呈现出非连续和连续条状形貌特征。然而,经深腐蚀后,晶内和晶界处形貌均发生了变化,即,沿晶界出现了大量白色絮状物,晶内则出现了具有金刚石结构的腐蚀坑。由于富Ni和富Cr区域具有更负的电极电位,因而使得这些区域在深腐蚀后更易被侵蚀。     

Der Einfluß der Strahlenschädigung durch schnelle Neutronen auf die Spannungsrißkorrosion (SKR) von Eisen-Chrom-Nickel-Stählen

Influence of radioactive deterioration by fast neutrons on stress corrosion cracking of chromium-nickel steels Neutron irradiation has a bearing on the mechanical properties of the pure and industrial steels investigated. The creep limit is increased while the range of uniform elongation is reduced. Under an integral fast neutron flux of about 2.5.10¹⁹ n/cm² there is a defined yield strength increasing the stress corrosion susceptibility and there are indications of intercrystalline cracking in some cases. The industrial alloy has exclusively transcrystalline cracks een after neutron irradiation; the crack density is higher than in the pure alloy.