Investigation on Dephosphorization of Stainless Steel

In the scale of ironmaking and steelmaking, the dephosphorization can be divided into four classes. The first level which is known very well by metallurgists is the dephosphorization for carbon steels and low alloy steels. The second level is that included in the pretreatment process of hot metal. It differs from the first level as it must consider how to treat the selective oxidation of ［P］ and ［C］. Furthermore, The contradictory of dephosphorization and desulphurization has to be harmonized. The third level is that for high alloy steels and the fourth is that for ferroalloys. In these cases, two technical ways either oxidizing dephosphorization or reducing dephosphorization can be selected. Whether which one is chosen, the key problem is to lower down phosphorous content efficiently meanwhile to keep the concentration of Cr and/or Mn almost lossless.　　The cheapest raw materials for the production of high alloy steel are the returning scrap of that steel. Raising the proportion of the returning scraps in the total amount of raw materials is a very important measure to decrease the production cost. In order to avoid an obvious oxidation of Cr, Mn and so on during that melting process it is impossible to adopt the oxidational dephosphorization procedures which is generally carried out in the production of low alloy steel. In this case, after returning several times the phosphorous content in the scraps is accumulated. And then it gradually approaches to the level specified in the standard of the steel. Finally, it will become a waste. It was estimated that the market demand on high alloy steels as stainless steels would rapidly grow. So the scraps containing low phosphorous is urgently needed in a great deal. 　　On the other hand, the standards of some high alloy steels, which are designated for extremely severe environment only, allow a very low phosphorous content. For example, it is claimed that W［P］<0.015 %—0.020 % if the stainless steel products will contact with urea or nitric acid. If the resistance to corrosive fatigue and welding crack is highlighted the phosphorous content should be decreased to less than (100—50)×10－4 %. And Koros P J et al estimated that dephosphorous to 14×10－4 % will be wanted［1］. 　　So far no technology for dephosphorization of stainless steels can be widely adopted in industrial scale. This will be one of the major research projects in the coming century. This paper devotes to a discussion on the strategy of oxidational dephosphorization and the improvement of the reductional dephosphorization.     

Analysis of CO2 emission and mitigation methods in integrated iron and steel works

CO2 emission of the steel industry takes up a great proportion of the total emission of the world.It is necessary to reduce the CO2 intensity of steel products in order to save energy,protect the environment and keep a sustainable development in the steel industry.Based on the research of steel products’ life cycle inventory,those who conducted this research have focused on the analysis of CO2 emission factors and measures.Adopting the life cycle inventory model of a certain steelmaking site,together with the Tornado Chart,the researchers have identified significant factors,provided some explanation,and suggested some possible measures to reduce CO2 emission.The results have shown that the most important factors are the CO2 intensity of blast furnace gas (BFG), hot metal ratio of basic oxygen furnace (BOF) and the material utilization efficiency.Accordingly,some measures such as removing CO2 in BFG,decreasing the hot metal proportion in BOF,and improve material utilization efficiency in each process,may be taken to decrease CO2 emission.     

稀土在双相不锈钢中的应用研究

就国内外稀土在铁索体+奥氏体双相不锈钢中的应用研究作了简单介绍,包括稀土对双相不锈钢的凝固组织、耐腐蚀性能和力学性能的影响,并探讨了稀土在双相不锈钢中的发展前景.     

不锈钢连铸坯轧制中板工艺研究

分析了不锈钢连铸坯轧制中板的原理并进行了生产试验。试验表明,该工艺简单易行。     

The 80-year history of duplex stainless steel

80 years has passed since duplex stainless steels were first produced and now they have developed into an integral series with the efforts on R & D and development of technology.In the recent decade, duplex stainless steels have been accepted by more and more customers and increasingly used. The first duplex grade produced in Sweden was 453E(26Cr-5Ni) in the 1930s,and then developed into 329.These two grades were characterized by high carbon content and called the first generation of duplex stainless steels.At that time,it was very difficult to add nitrogen into the steels and maintain the phase equilibrium,thus influencing the application properties,for example,intergranular corrosion post welding. One method to solve this problem is to alter the chemical composition,like adding nitrogen,etc.And that came to reality with the development of AOD and metallurgical theory of stainless steels.New series of duplex grades,called the second and third generations duplex,have successively emerged since the 1980s. These grades are characterized by high amounts of alloying elements,like chromium,molybdenum and nitrogen.Furthermore,super duplex stainless grades,like S32750,S32760 and S32707,were developed for various harsh service environments with their outstanding corrosion resistance and workability.These grades possess corrosion resistance corresponding to super austenitic grades,or close to nickel-base alloys, and are used in ocean-engineering,sea water desalination and oil industries,etc. And the application of duplex stainless steel is expending into other industries.For instance,453E is used in the pulp & paper industry.2205(S32205),a medium-alloyed grade,has become the most typical one in the duplex stainless steel family and widely used in many industries like pulp & paper,chemical and oil.New applications are emerging with better understanding of the duplex grades. Modern duplex stainless steels features most the corrosion resistance and strength,making them most cost-efficient in more and more projects. In this paper,the history of duplex stainless steels is recalled and reviewed from R&D,production to application,and latest grades like S82441 are also introduced.     

太钢VOD冶炼超纯铁素体不锈钢的工艺技术进步

阐述了超纯铁素体不锈钢的超低碳氮的特点及其熔体降碳去氮困难的原因,利用真空降碳去氮的理论结合这方面的研究成果分析和讨论了影响VOD脱碳脱氮的影响因素,并利用VOD现场冶炼的具体数据进行了这些因素的统计分析,在此基础上提出了提高真空度、加强底吹氩搅拌强度、提高入炉钢液温度、提高人炉碳含量和降低人炉氮含量、增加VOD吹氧脱碳时的供氧量、高真空吹氩纯沸腾工艺、选用无碳、或低碳还原料等工艺技术措施,最后介绍了太钢这几年在VOD冶炼超纯铁素体不锈钢采取上述措施后所取得的效果。     

资源可持续性分析

在分析地球能量平衡和资源分类的基础上,提出了资源可持续利用的理想模式。认为现阶段所谓资源持续利用只是相对的资源持续利用,并说明了具体含义。     

Corrosion behavior of super 13Cr stainless steel in a H_2S and CO_2 environment

The corrosion behavior of 95 ksi grade super 13 Cr stainless steel in an environment consisting of H_2S and CO_2 was investigated.The results reveal that for both loading methods(constant load and four-point bending),local corrosion occurred on the surface of the samples tested at ambient temperature but was absent from the samples tested at high temperatures.The local corrosion was caused by the formation of pits at nonmetal inclusions; the pits were formed under the action of stress in an acidic environment, which was due to an acid solution.Subsequently, the corrosion extended along the direction of stress.The sensitivity of stress corrosion cracking increased because of the local corrosion.     

高氮不锈钢粉末冶金制备技术的研究进展

高氮不锈钢作为一种重要新型工程材料,具有优异的力学性能和耐腐蚀性能,受到国内外广泛重视。介绍了粉末冶金制备高氮不锈钢的原理和特点;论述了高氮不锈钢粉末的制备与成形技术;指出了利用粉末冶金制备高氮不锈钢所具有的技术优势,其中注射成形——氮化烧结工艺更具发展潜力。     

超级13Cr在H2S和CO2共存环境下的腐蚀行为影响研究

对CO2和H2S共存环境中95 ksi钢级超级13Cr钢的腐蚀行为进行了研究,发现常温条件下H2S和CO2共存环境中,无论是采用恒载荷的方法还是四点弯曲的方法,都在试样的表面出现了局部腐蚀,而在高温条件下未发生点蚀和应力腐蚀现象。分析结果表明,95 ksi钢级的超级马氏体不锈钢在常温H2S和CO2共存环境中出现的局部腐蚀主要是因为夹杂物在应力集中和酸性溶液的作用下形成点蚀,并沿着相同应力水平的区域扩展,局部腐蚀增加了应力腐蚀开裂的敏感性。     

崛起的宝钢集团不锈钢精品基地--不锈钢分公司不锈钢工程介绍

介绍了宝钢股份公司不锈钢分公司不锈钢工程的建设背景、生产工艺流程和装备情况,建成投产后的生产情况.文章还结合中国不锈钢市场的发展趋势,描述了不锈钢精品基地建设的后续规划.     

钢铁生产过程二氧化碳排放计算方法与实践

 钢铁生产过程二氧化碳排放量的精确计算是钢铁行业节能减排的基础。对钢铁生产流程二氧化碳排放的3种常用温室气体排放计算方法进行介绍,并基于A钢厂2014年的生产数据进行计算和分析对比。《省级温室气体清单编制指南》、《钢铁碳排放指南》两种计算方法都是基于投入产出的统计方法,两者温室气体计算结果数值相近,前者吨钢二氧化碳排放结果为2.116 t,后者吨钢二氧化碳排放结果为2.013 t ,后一种方法在计算时考虑了固碳产品的抵扣,所以结果比前种方法结果偏小。基于ISO标准的钢铁产品生命周期计算方法,计算边界从铁矿石、煤炭等原材料的采掘、洗选、运输,焦化,烧结,高炉,炼钢,轧制等直到钢铁产品的出厂,计算结果吨钢产品二氧化碳排放量为2.309 t,相比前两种方法计算结果数值较大,这是因为在计算时包含了铁矿石、煤炭等在开采、洗选、运输阶段产生的二氧化碳。     

X射线荧光光谱法测定不锈钢的分析研究

通过X射线荧光光谱法测定不锈钢的分析实验,找出了影响其分析精度和准确度的各种因素,并就其主要影响因素X光管的功率选择、试样的制备、类型标准化的参数设定等方面进行了分析研究.研究结果显示：应用X射线荧光光谱法测定不锈钢可完全替代化学湿法分析.     

煤气加热器法兰螺栓失效分析

通过化学分析、电子显微镜等物理化学检测手段,对煤气加热器不锈钢螺栓失效的原因进行了分析,结果表明螺栓失效的原因为硫化物所导致的应力腐蚀。     

A roadmap to carbon-lean steel

The steel industry has come a long way in increasing its energy efficiency.In Europe the carbon intensity of steelmaking over the last 40 years was decreased by a factor 2.The potential for further improvements is now becoming less obvious as blast furnace operations are approaching the thermodynamical lower limit of hot metal production.To take on the climate change challenge and be able to respond to the expectation for strong reduction of carbon emissions,ArcelorMittal（AM） has developed a two step approach: （1） In a first instance given the modest remaining potential for incremental improvements precise benchmark tools were developed.This allowed identifying the top runners and determining the remaining potential for improvement.Plans were developed to bridge the gap with this achievable performance.In total a plan was devised with more than 400 identified actions throughout the group.This action plan will allow achieving a further 8% increase of CO₂ efficiency by 2020. （2 ） Secondly,already in 2002 AM engaged in the development of breakthrough technologies to further drastically reduce the carbon intensity of steelmaking.After screening a large number of candidates a few were selected for further development.A first breakthrough technology which is the most advanced stage of development can be applied to existing blast furnace and is reaching maturity and a demonstration on industrial scale of this technology is under preparation.In itself this technology will decrease the dependency on carbon as well as increase the productivity of the original blast furnaces.Real big gains can be made if this technology can be combined with underground carbon storage. In the AM roadmap the impact of raw materials（DRI,scrap） was excluded.In the longer run however the attention will have to turn to the overall footprint of materials and the long term consequences of the choice of materials.Increasing the recovery while preserving the quality of used steel products will leverage greatly the efforts done in the production of primary and secondary steel and power.     

我国不锈钢工业所处的环境与发展分析

近年来全世界不锈钢生产与消费增长很快，生产技术不断发展。据预测，到本世纪末全世界不锈钢将处于产大于消。而我国不锈钢的生产不仅产能低、设备装备水平差，而且在产品质量、品种结构等方面都存在很多问题，近年来自给率不足50％。世界上主要不锈钢生产国都把目标瞄准了中国，必然会对我国不锈钢的发展带来强烈的冲击，加大我国不锈钢工业的发展力度，使我国不锈钢工业在较短时期有大的发展刻不容缓。     

中国不锈钢市场与发展中的宝钢不锈钢事业

描述了世界不锈钢市场供需变化的基本特征、供需区域转移的基本趋势及中心转移的中国因素,剖析了中国不锈钢行业的竞争态势、机会与挑战,阐述并提出了宝钢进一步发展不锈钢事业的主要方向:积极进取,实现不锈钢技术创新能力的提升;统筹规划,优化、整合宝钢内外不锈钢资源;立足国内,面向全球,开拓多层次不锈钢消费市场;扩大合作领域,营造具有可持续竞争能力的不锈钢供应链;努力维护不锈钢行业持续、健康发展的良好环境.