高镍奥氏体球墨铸铁涡壳的开发

针对D-3.5和D-5S两种材质的高镍奥氏体球铁涡壳进行了试验研究,认为奥氏体枝晶发达才是高镍球铁出现碎块状石墨和显微缩松难以消除的根本原因.通过MAGMA模拟软件进行了铸造工艺模拟分析,优化了铸造工艺,缩短了开发周期,降低了成本.采用长效的Si-Ba和Si-Sr孕育剂的多次孕育,并加入微量的Sn和Sb元素,同时严格控制化学成分、出铁温度等关键参数,解决了球化不稳定、碎块石墨和显微缩松等问题,成功完成了高镍奥氏体球铁涡壳的开发,掌握了高镍奥氏体球铁的批量生产技术.     

高镍球铁奥氏体枝晶金相显示方法研究

高镍球铁在高端铸件如汽车发动机排气歧管、涡轮壳和核电用空压机壳体等铸件上的应用日趋广泛。为了深入研究高镍球铁的凝固特征及组织形成规律,根据着色腐蚀法原理,探索了适合高镍球铁高温凝固组织常温金相显示的着色腐蚀方法及特点,优化了腐蚀剂配方和腐蚀工艺,为高性能高镍球铁铸件研发和内在质量控制提供了良好的研究和分析手段。     

高镍D5B奥氏体球铁排气管的生产工艺

总结了高镍球铁排气管铸件的铸造工艺,对影响高镍奥氏体球墨铸铁球化率和力学性能的饱和度数据做了新的探索,当饱和度A达到4.9时也生产出了球化合格的铸件.把均衡凝固技术运用到高镍奥氏体球铁铸件,克服了热节处碎块状石墨的问题.通过与国外某公司退火处理比对试验,验证了本文的热处理工艺是合理的.生产出的铸件远远超出了ASTM标准规定的力学性能指标,达到了抗拉强度大于400 MPa的概率为100%.     

铁型覆砂无冒口铸造增压器涡轮壳

铁型覆砂铸造技术是一种清洁、高效的铸造技术,采用铁型覆砂技术生产中硅钼铁素体球铁增压器涡轮壳,铸件尺寸精度、表面质量、内部质量均有明显改善,已铸造增压器涡轮壳20余万件,效果良好,对铁型覆砂铸造工艺的应用有良好参考价值。     

铸态高镍奥氏体球墨铸铁稳定化生产

分析了一些主要元素对高镍奥氏体球铁组织和性能的影响,确定了合理的内控化学成分。球化处理采用冲入法,镍镁合金球化剂用量为铁液重量的0.7%~0.9%,球化后高镍奥氏体球铁Mg残留量为0.07%~0.09%。采用硅铁和硅钡孕育剂炉前孕育,孕育剂用量为铁液量的1.0%~1.5%。采用以上工艺方法生产的铸态高镍奥氏体球铁力学性能合格率明显提高。     

高镍奥氏体球墨铸铁质量的炉前在线控制

采用计算机辅助热分析系统完成了高镍奥氏体球铁的炉前质量控制.试验结果经统计学分析用于在线控制获得满意结果.试验结果表明,高镍奥氏体球铁的液相线温度和碳当量之间的关系可表达为CE=15.7826-0.0096575TL.为了满足高镍奥氏体球铁的抗拉强度大于400MPa的概率为99%的要求,高镍奥氏体球铁的液相线温度应控制在1203℃～1226℃范围内.     

高镍奥氏体球墨铸铁铸件的生产工艺研究

介绍了高镍奥氏体球墨铸铁铸件的化学成分选择、熔炼及浇注工艺过程.分析了铸件在批量生产中球化率不稳定导致力学性能不良的原因,通过控制浇注时间和保证不中断随流孕育进行了改善.同时,通过使用回炉料和高镍奥氏体球墨铸铁铸件加工铁屑,在保证产品性能稳定的情况下,节约了生产成本.     

AlSi7Mg汽车涡轮增压器压壳重力铸造数值分析与缺陷预测

涡轮增压器压壳形状复杂,在重力铸造过程中工艺控制困难,容易产生各种铸造缺陷。针对以上问题,利用Magmasoft软件对Al Si7Mg汽车涡轮增压器压壳铸造过程进行数值模拟,分析了充型过程的温度场;基于Porosity和Niyama判据成功预测了铸件可能出现的铸造缺陷。     

中镍无磁奥氏体球墨铸铁的研究

系统地介绍了6%镍奥氏体球铁的机械性能与金相组织、化学成分之间的关系;并测定其电磁性能;进行了奥氏体球铁金具和可锻铸铁全具的磁损对比实验,对6%镍奥氏体球铁金具,进行了握力试验和荷重破坏试验。实验结果表明,含6%镍奥氏体球铁的延伸率高达15%,抗拉强度均在400MPa以上,高者达550MPa;电阻率P值在1．0Ω·mm2/m以上,是可锻铸铁的两倍多,磁场强度H＝100Oe时,相对磁导率μr值为1．1~1．5,近似无磁;当电流为450安培时,每个奥氏体球铁金具比可锻铸铁金具节能约40瓦;铸造合格的金具,通过了GB2317-85的握力试验和荷重破坏试验。     

硅酸乙酯型壳内表面析出物的控制

前言 用硅酸乙酯水解液作为型壳粘结剂,其代表缺陷是型壳内表面有析出物,并产生以下几种铸造缺陷。 1.要求晶粒细地的零件得不到应有的细化效果。 2.铸件表面有麻坑。 3.铸件内部有夹砂存在。 一、硅酸乙酯水解液型壳内表面析出物的形态及对铸件质量的影响。 我车间生产的某航空发动机中的燃气涡轮导向器、自由涡轮导向器、20GJ废气涡轮增压器中的涡轮和叶轮,均属带叶片的整     

Low-temperature nitriding of austenitic steel in a vibrofluidized bed

The prospects for use of a vibrofluidized bed (VFB) for low-temperature nitrogen saturation of high-strength austenitic steel based on Cr−Ni−Mn (12Kh17N8G2S2MF) are considered. The positive effect of preliminary plastic deformation on the intensity of nitriding is described. The temperature and time parameters of nitriding in a VFB for strain-aging austenitic steel 12Kh17N8G2S2MF are shown to be adequate for the regimes of the final heat-treatment operation of aging. This creates the possibility of combining the operations of surface alloying and strain aging into a single cycle. This combined treatment increases substantially the resistance of the steel to cyclic loads while preserving the strength parameters. It is shown that the presented method of low-temperature nitriding in a VFB is expedient for improving the service characteristics of austenitic steel 12Kh17N8G2S2MF used for production of force springs of automobile brake systems. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 6–10, November, 1999.     

DEVELOPMENT OF INCONEL~ ALLOY 783，A LOW THERMAL EXPANSION，CRACK GROWTH RESISTANT SUPERALLOY

ＤＥＶＥＬＯＰＭＥＮＴＯＦＩＮＣＯＮＥＬ~ＡＬＬＯＹ７８３,ＡＬＯＷＴＨＥＲＭＡＬＥＸＰＡＮＳＩＯＮ,ＣＲＡＣＫＧＲＯＷＴＨＲＥＳＩＳＴＡＮＴＳＵＰＥＲＡＬＬＯＹＪ．Ｈ．Ｔｈｎｄｅｒｍａｎｎ（ＩｎｃｏＡｌｌｏｙｓＩｎｔｅｒｎａｔｉｏｎａｌ,Ｉｎｃ．...     

High corrosion resistance of austenitic stainless steel alloyed with nitrogen in an acid solution

Passivity of austenitic stainless steel containing nitrogen (ASS N25) was investigated in comparison with AISI 316L in deareated acid solution, pH 0.4. A peculiar nature of the passivation peak in a potentiodynamic curve and the kinetic parameters of formation and growth of the oxide film have been discussed. The electronic-semiconducting properties of the passive films have been correlated with their corrosion resistance. Alloying austenitic stainless steel with nitrogen increases its microstructure homogeneity and decreases the concentration of charge carriers, which beneficially affects the protecting and electronic properties of the passive oxide film.     

轨道车辆用不锈钢材料的火焰调修工艺

通过热处理试验研究了火焰调修工艺对S30103-1/8 Hard奥氏体不锈钢的拉伸性能、冲击韧性、硬度、中值疲劳极限以及耐晶间腐蚀性能的影响,回归得到了疲劳寿命曲线,为美标轨道车辆制造提供工艺指导。结果表明:S30103-1/8 Hard奥氏体不锈钢的显微组织为变形奥氏体组织,受热后力学性能容易波动。当火焰调修温度在450~850℃范围内,不锈钢的力学性能、抗晶间腐蚀性能随温度升高呈下降趋势。在调修温度为450℃条件下,增加调修次数对不锈钢板材的抗晶间腐蚀性能和疲劳强度影响不大。因此,选择调修温度不应超过450℃,在此温度下可以进行多次调修。     

Dislocation configurations and stress-corrosion properties of alloys in the nickel—chromium—iron system

Abstract

Stress-corrosion tests have been performed in sodium chloride at 300° on commercially produced and laboratory-made nickel alloysand austenitic steels. It has been found that resistance to transgranular stress corrosion cracking depends upon the (Ni + Cr) content. Commercial high-Ni alloys are resistant, as are relatively pure Ni–Cr–Fe alloys with (Ni + Cr) ≥ 50% wt. The resistance of alloys with approximately 20% Cr and 20—40% Ni is markedly influenced by other alloying elements, for example, silicon and molybdenum.

Electron microscope studies indicate that resistance to cracking can be approximately correlated with the extent to which dislocation ‘tangling’ occurs at a particular deformation. Planar dislocation arrays appear to be a necessary, though not sufficient,condition for susceptibility. It is thought that the observed dislocation arrangements can be understood without recourse to hypotheses of ordering in these alloys. The influence of some alloying elements, e.g. chromium and silicon, cannot be interpreted simply in terms of their influenceon dislocation arrangements. The favourable effectof these elementson resistance to stress-corrosion cracking is probably associated withtheir ability to increase the protective properties of surface oxide films and thus to inhibit the crack initiation process.     

涡轮增压器壳体用铸造合金及生产工艺现状

涡轮增压器壳体是汽车涡轮增压器的关键部件之一.本文概述了涡轮增压器壳体用材质的化学成分、性能特点及其在铸造生产中所存在的问题.指出采用壳型铸造、覆膜砂制芯、发热保温冒口等工艺,同时合理控制浇注温度及炉前合金化处理,是获得优质壳体铸件的有效途径.     

Photocurrent and capacitance investigations into the nature of the passive films on austenitic stainless steels

Photocurrent and capacitance measurements of semiconductor passive films formed on metals and alloys can be used to study the electronic properties and reveal indirect information about structure and composition. The current work used these techniques to investigate the electronic properties of the passive films formed on three austenitic stainless steels, types 304L, 316L and 254SMO, in borate. Evidence was found for the existence of a large number of localised mid bandgap states, consistent with amorphous oxides. However, the flat-band potentials of the austenitic stainless steel passive films were found to be independent of both composition and measuring frequency. The most credible explanation for the bandgap values determined from photocurrent measurements is that the passive films are formed as dual layers, iron oxide outer layer and chromium oxide inner layer. This model does not need to evoke the potential dependent bandgaps used by previous authors.     

Eigenschaftsprofil des neuentwickelten Stahls X2 CrNiMnMoN 23 1764

Properties of the newly developed steel X 2 CrNiMnMoN 23 17 6 4 A well balanced alloying composition allows to produce the high alloyed stainless steel X 2 CrNiMnMoN 23 17 6 4 containing more than 0.4% nitrogen by conventional processes. Features of this material are a stable fully austenitic microstructure, 0.2% yield strength higher than 420 N/mm², excellent corrosion resistance and good working and welding properties. The critical pitting temperature evaluated in ferric chloride solution according to ASTM G 48–76 standard is higher than 85 deg C and it is only lightly lowered when tested in the as welded condition. By these properties Remanit 4565 S may bridge the gap between high-alloyed stainless steels and non-ferrous materials for applications in the chemical process industries.     

亚稳奥氏体金属抗空蚀性能及其主要控制因素

用旋转圆盘实验机对5种亚稳奥氏体金属的抗空蚀性能和水轮机叶片用0Cr13Ni5Mo不锈钢进行了对比研究。结果表明，2种应力诱发马氏体Fe-Mn-Si-Cr形状记忆合金的抗空蚀性能远高于3种应变诱发马氏体相变奥氏体不锈钢和0Cr13Ni5Mo不锈钢。高的局域弹性性质he是Fe-Mn-Si-Cr形状记忆合金具有高抗空蚀性能的主要原因。he是影响亚稳奥氏体金属抗空蚀性能的首要控制因素，空蚀诱发马氏体耗散能量，空蚀表层硬度及加工硬化能力是影响亚稳奥氏体金属抗空蚀性能的第二控制因素。     

Localized corrosion of (lean) duplex stainless steels in immersion units of urban wastewater treatment plants

With lower alloying cost and higher mechanical properties, lean duplex stainless steels can be an alternative to the more commonly used austenitic stainless steels. However, these alloys are still not the preferred choice, probably due to a lack of field experience. A study was thus initiated in view of defining the limits of use of selected (lean) duplexes for urban wastewater treatment units. The present paper shows the localized corrosion performance of selected lean duplexes in chloride contaminated solutions. The results are compared with austenitic S30403 and S31603 and with the more standard duplexes S82441 and S32205. The effect of welding was also investigated. Exposures in field municipal wastewater plants were conducted for 1 year in low and high chloride content units. The results show that lean duplexes S32101 and S32202 can be used as alternatives to S30403 and S31603 in low chloride electrolytes. At 500 ppm of chloride content, duplex stainless steel S32304 showed better corrosion resistance than S30403 and S31603. For higher chloride contents (1000 ppm and above) the standard duplexes S82441 and S32205 shall be preferred.