铸铁孕育处理时的石墨核心研究

将铁水用75FeSi孕育后液淬,终止其溶解过程,在溶解区中出现已经生长石墨相的非金属夹杂物,它们随后又溶回铁水中去.但已经复盖有石墨相的晶核能存在较长的时间孕育剂的作用是提供一个碳的过冷溶液,使位于其中的非金属夹杂物活化成为晶核     

硫质量分数对船体钢诱发点蚀行为的影响研究

采用腐蚀浸泡的方法研究了酸性氯离子环境下S质量分数对低合金船板钢耐蚀性的影响,探讨了非金属夹杂物诱发点蚀形核的机理。结果表明,杂质元素S对钢的耐蚀性具有不利影响。随着S质量分数的增加,钢的耐点蚀性能恶化。S元素损害耐蚀性主要与钢中的非金属夹杂物有关。不同种类夹杂物诱发点蚀的机理有显著差异。单一MnS夹杂物与基体间存在缝隙,其诱导点蚀形核包括缝隙腐蚀和夹杂物溶解两个过程,MnS夹杂物是最敏感的点蚀诱发源;MXS-Al2O3复合夹杂物同样能诱发低合金钢的点蚀形核,包裹在Al2O3外层的硫化物优先发生溶解,成为腐蚀介质的通道,从而引发局部腐蚀。MnS-Al2O3夹杂物的点蚀形核能力大于CaS-Al2O3夹杂物,CaS遇到水容易发生水解并在夹杂物周边形成OH-,阻碍了坑内部的酸化,有利于抑制钢的耐局部腐蚀性能。     

The influence of non-metallic inclusion nature and shape on the pitting corrosion susceptibility of 18Cr9Ni and 17Cr11Ni2Mo austenitic stainless steels

The influence of the nature and shape of non-metallic inclusions on the nucleation and growth of the pits in aqueous 3% NaCl solutions of different pH values on 18Cr9Ni and 17Cr11Ni2Mo stainless steels is examined. Pits are always localised on sulphides and mixed inclusions. The potential-pH fields which determine the preferential dissolution of the sulphide inclusions are drawn. Sulphide dissolution is a condition necessary but not sufficient for the nucleation of pits since not only the nature of the inclusions but also the shape is effective in determining the probability of pitting nucleation. The higher reactivity of the transverse sections of a stainless steel in comparison with the longitudinal ones is explained by the more unfavourable inclusion shape in that direction. The influence of the inclusion shape becomes less and less important as the bulk solution pH is lower or the etching potentials higher.     

Effects of processing variables on melt cleanliness of AZ31B magnesium alloy investigated by quantitative evaluation of Fe and non-metallic inclusions

Impurities such as Fe, Ni and Cu and non-metallic inclusions such as oxides, nitrides, carbides, sulfides and fluorides are harmful to the quality and various properties of magnesium alloy sheets produced by twin-roll casting. In this study, the changes of the content of Fe and non-metallic inclusions in AZ31B magnesium alloys with melt temperature and isothermal holding time were quantitatively evaluated using EPMA and the metallographic method. The Fe content did not increase above the Fe content in the raw material, which implies that the dissolution of Fe from a steel crucible was suppressed effectively. The content of non-metallic inclusions, mainly consisting of oxide, fluoride and Fe-rich intermetallic compounds, did not change remarkably with the melt temperature but it increased with the isothermal holding time due to the continuous oxidation of the magnesium alloy melt on the melt surface.     

A STUDY OF ELECTROLYTIC SEPARATION OF NONMETALLIC INCLUSIONS IN LOW CARBON STEELS

木文叙述对电解分离低碳鋼非金属夾杂物进行系统试验的结果,并针对现有电解分离夾杂物方法提供了某些改进的意见. 对分离稳定夹杂物而论,试验结果指出用硫酸亚鉄法(一种溶液)进行电解再用过硫酸铵法或硝酸法破坏碳化物是较为适当的;对分离不稳定夾杂物则以用亚硫酸钠法(两种溶液)较为满意. 应用上述方法并结合金相检查对某种低碳结构鋼材进行试验,得到了有意义的结果.     

Purifying effect of new flux on magnesium alloy

1　INTRODUCTIONAsoneofthelighteststructurematerials ,mag nesiumalloysofferlightmass(ρ<2 g·cm- 3) ,specif icstrength (higherthanthatofthealuminumalloysandsteels) ,specificstiffness ,excellentmachinabili ty ,superiordampingandmagneticshieldingcapaci ties,whichleadstoagrowinginterestinmagnesiumanditsalloys .Inrecentyears ,magnesiumalloyshavebeenwidelyusedinaviation ,spaceflight,automobileandelectronicsindustries[1] .Since 1990 stheirappli cationhassteadilyextendedanditispredictedthatitwill…     

影响鞍钢X70管线钢CO2腐蚀行为的环境因素和材料因素

利用失重法、扫描电镜等,研究了X70管线钢在CO2分压为2MPa的NACE溶液中高温高压环境下的腐蚀行为,结果表明,温度和Cl-是影响X70钢腐蚀的主要环境因素,随温度的升高均匀腐蚀速率增大。钢中珠光体、粒状贝氏体组织及非金属夹杂物MnS、CaS等在腐蚀环境中促进了管线钢的腐蚀。因此在材料方面要降低珠光体及粒状贝氏体含量,细化夹杂物,并降低夹杂物级别。     

Non-metallic Inclusions and the Failure of Ferritic-Pearlitic Cast Steel

Abstract

The author has examined the effect of non-metallic inclusions on the initiation and propagation of micro-cracks in a cast steel. It has been found that the first microcracks appear in non-metallic inclusions irrespective of the method of loading the samples used in the investigation. The value of the microstresses in the inclusions was measured experimentally and the effects of composition, shape and size of non-metallic inclusions on the processes leading to the generation of cracks were ascertained. The critical size of inclusions which failed to cause the formation of microcracks in steel was also determined.     

OTSInca在钢铁非金属夹杂物检测中的应用

从系统组成、工作原理、功能介绍和特殊优势等4个方面详细介绍了一款钢铁非金属夹杂物自动分析系统-OTSInca软件。该软件功能强大、操作便捷,可以自动、高效、准确地表征非金属夹杂物的分布、成分和形态信息,结合其强大的数据库系统,可以自动识别出非金属夹杂物的种类。同时,该系统在操作界面、数据采集、数据库、报告输出等4个方面具有独特的优势,也极大地提高了非金属夹杂物自动识别的效率和准确性。     

计算热力学在钢中非金属夹杂物研究中的应用

简要介绍了采用计算热力学方法分析钢中非金属夹杂物形成过程中涉及到的多元多相体系的热力学模拟。尝试应用Thermo-Calc软件系统对非金属夹杂物的形成热力学进行了探讨。指出,尽管Thermo-Calc软件具有较强的实用性,但为了拓宽该软件的工业应用前景,应对其中的SLAG数据库进行必要的完善。     

A study on elimination of alumina particles in molten aluminum using direct electromagnetic force

From the viewpoint of energy reduction, the recovery of metal scrap and its recycling have been rising as an important global subject. However, it is difficult to remove deleterious impurities, which have detrimental effects on the mechanical properties. In particular, it is difficult to eliminate nonmetallic inclusions such as alumina(Al₂O₃) in aluminum alloys when they are subject to recycling. In this study, an experiment on the elimination of the impurities in the melt by imposing electromagnetic force to molten aluminum was conducted. The principle behind these electromagnetic methods is that as the electromagnetic force induced in metal scarcely acts on non-metallic inclusions due to low electric conductivity, the non-metallic inclusions are moved to the direction opposite the electromagnetic force and can be separated from the melt. The prediction based on the theoretical analyses was confirmed through the visualization of the polystyrene particle motion in an NaCl aqueous solution. We also proposed optimum electromagnetic conditions such as current density, magnetic field intensity and particle size for eliminating the inclusion particles continuously found through numerical analysis and experiments.     

ULTRASONIC SEPARATION OF MICRO-SIZED INCLUSIONSIN MOLTEN METAL

1. IntroductionMicro-sized non-metallic inclusibns in metal are usually detrimental to the metal ma-trix from the points of precise machining, deformation and corrosion. Therefore, theseinclusions should be removed from molten metal by using an efficient separation method.The routine methods involve floatation-separation methodology based on natural densitydifferences, ceramic filters or fine~bubble-assisted floatation-separation, and new separa-tion methods using electric or magnetic flelds h…     

Effects of CeF3 on properties of self-shielded flux cored wire

0 IntroductionSelf-shielded flux cored wire is a newly developedwelding material used without gas protection. Use of suchcored wires has grown rapidly in developed countriesbecause of the following advantages: simple use, goodwind resistance ability, lower cost resulted from highproductivity and strong desulfurization ability[1]. Self-shielded flux cored wires are preferred for on-site weldingsuch as ship and barge building, storage tank, bridge,offshore oil platform buildings and so on[2 -3].…     

Non-Metallic Inclusions,Their Quantitative Extraction from Steel

An important factor in steel quality—non-metallic inclusions—can making practices. As a first step in effecting this control, the authors show that quantitative extraction and analysis of non-metallic inclusions in low- and medium-alloy steels is practicable.     

4J43膨胀合金底吹氩工艺的物理模拟及工业应用

钢包底吹氩工艺是一种经济实用且简单易行的精炼方法,通过实验室物理模拟确定出膨胀合金4J43在底吹氩工艺中氩气流量应控制在3~7 L/min之间。在该流量范围内,合金液的混匀时间随氩气流量的增加而减少。在合适的吹氩参数下进行工业生产,实验结果表明：吹氩工艺对4J43膨胀合金中氧元素及夹杂物的去除效果明显。当氩气流量为5 L/min时,与未吹氩相比合金中氧元素含量下降56.98%,非金属夹杂物总量减少46.43%,合金中大尺寸夹杂物数量明显减少,合金在室温下的各项力学性能与同组相比均得到很大提高。     

氧气顶底复吹转炉冶炼45#钢铸坯的质量研究

氧气顶底复吹转炉冶炼45#钢,其连铸坯产品用于制造热墩螺栓.生产过程中钢液的脱氧程度决定了钢中非金属夹杂物的形态和行为,直接影响到钢的冶炼品质.通过对转炉冶炼工艺终点氧的控制,对45#钢连铸坯中非金属夹杂物的形态与行为的影响做了深入的研究.提出了改善产品质量的措施和提高钢的纯净度的手段和方法.     

X100管线钢焊接接头抗HIC性能研究

利用OM和SEM研究了X100管线钢焊接接头的微观组织,并利用EDS分析接头中的非金属夹杂物种类及成分。结果表明,实验用X100管线钢焊接接头由针状铁素体、粒状贝氏体和M/A岛组成;焊缝金属中含有MnS,Si的氧化物和Al的氧化物及Al-Mg-O和Ca-Al-O-S系夹杂物。焊接接头氢致开裂敏感性较高,焊缝金属中的非金属夹杂物及硬脆M/A组元与基体之间的界面和应力导致氢致裂纹的萌生,并沿粗大的贝氏体晶粒扩展。     

非金属夹杂物在镍基粉末高温合金中的变形行为

对人工掺入FGH96合金中的Al2O3、SiO2及莫来石三种夹杂物在等温锻造过程中的变形行为进行了研究,并对夹杂内部及其周围基体中的等效应力和等效应变分布进行了模拟。结果表明,夹杂内部的应力集中是使其破碎的原因,较大的剪切应变导致其一维方向的尺寸变大,使裂纹极易在夹杂处萌生并扩展,从而增大了对基体材料的危害性。但夹杂的种类不同,在变形过程中表现出的行为特征也不尽相同：Al2O3呈破碎的“链状”分布;SiO2只发生局部破碎;莫来石呈“薄膜”状分布。通过大的变形量和挤压比,可降低非金属夹杂物对粉末高温合金盘件工程化应用的影响。     

电磁过滤钢液中非金属夹杂物的运动速度和去除效率的理论分析

电磁过滤原理是根据非金属夹杂物与熔体导电性的差异,在电磁场作用下非金属夹杂物与熔体的运动规律不同,使非金属夹杂物与熔体分离,经流体力学分析、采用柱塞流及轨线模型研究电磁过滤水平流动钢液中非金属夹杂物的运动速度和去除效率,结果表明,非金属夹杂物的去除效率随着熔体流速（u)和过滤器的高度（2h)的降低而增加;随着电磁力（f)、电磁力作用区长度（x)和非金属夹杂物的粒径（dp)的增加而增加,经分析表明,采用电磁过滤法可有效去除粒径小于10um的非金属夹杂物,该模型可用来设计过滤器的结构和确定电磁过滤工艺参数,为电磁去除钢液中的非金属夹杂物技术的工业应用提供理论基础。     

钛微合金化Q390钢的纯净度研究

针对国内某钢厂生产的含Ti微合金钢Q390（采用BOF-LF-RH-CC工艺流程）,对LF处理前、LF处理后、RH处理后、中间包环节及连铸坯取样,通过光镜、电镜能谱分析及大样电解等手段研究分析了该钢种的纯净度和夹杂物演变行为。结果表明：该钢种工艺生产过程稳定,生产的钢水纯净度较高,铸坯中大型夹杂物数量为1.4 mg/10 kg,夹杂物以CaO-SiO2-Al2O3复合为主,一些大型夹杂物中复合了较高含量的Ti。另外,对钢中一些典型夹杂物的产生机理进行了阐述。