Innovative Iron and Steelmaking

This paper addresses the need for radically new innovative technology to produce liquid iron and steel. The salient features of these so called “direct smelting” processes are also discussed, as are the developments in iron blast furnaces and steelmaking technology and processes. The energy required for a direct smelting process, based on injection of coal and domestic iron ores and other raw materials, has been calculated and compared with various similar direct smelting processes as well as existing blast furnaces. Finally, the future trends in the liquid iron and steelmaking technology and processes have been speculated.     

The influence of Mn compared to that of Cr,Mo and S on the resistance to initiation of pitting and crevice corrosion in austenitic stainless steels

A large number of production and laboratory heats in grades AISI 304 and 316 with normal and extremely low managanese and sulphur contents and a number of production heats in more highly alloyed austenitic stainless steels have been studied with regard to their resistance to initiation of pitting and crevice corrosion at various temperatures. The criteria for resistance to initiation was the potentiodynamic pitting potential in 0.1 M NaCl and synthetic seawater and the time to attack initiation for crevice corrosion in 0.5 and 5% NaCl solutions. A large number of production and laboratory heats in grades AISI 304 and 316 with normal and extremely low managanese and sulphur contents and a number of production heats in more highly alloyed austenitic stainless steels have been studied with regard to their resistance to initiation of pitting and crevice corrosion at various temperatures. The critieria for resistance to initiation was the potentiodynamic pitting potential in 0.1 M NaCl and synthetic seawater and the time to attack initiation for crevice corrosion in 0.5 and 5% NaCl solutions. The main aims of the study were to examine both the effect of manganese relative to that of chromium, molybdenum and sulphur and the effect of heat treatment and sulphide composition on steels with low manganese contents. Mathematical models for calculation of the pitting potentials have been constructed and multiple linear regression analysis gave the equations and their reliabilities. Lowering of the Mn content in austenitic stainless steels to 0.2% gives rise to a material of interest for constructions where pitting or crevice corrosion are judged to be the only potential types of attack, where operational disturbances leading to greatly increased corrosivity do not occur, where attack can not be tolerated, and where steel with normal managanese content has not exhibited fully satisfactory corrosion resistance. If the above conditions are fulfilled the low manganese content can be said to correspond to the same positive effect as is obtained by an addition of the least 1.5% Mo.     

电弧炉生产低磷合金钢P22管坯工艺实践

介绍了以废钢和没有经预处理脱磷的高磷铁水为原料,采用电弧炉生产低磷合金钢P22(P含量小于0.008%)的冶炼工艺。通过电弧炉早期造渣提前脱磷,用石灰作脱磷剂,采用大渣量、多次换渣等工艺,高碱度与高氧化铁的合理匹配和熔池的强烈搅拌以及高温抑制回磷技术,实现电弧炉初炼钢水P含量小于0.003%。通过控制铁合金增磷和炉渣回磷技术措施,采用电弧炉冶炼工艺,可批量生产出高质量的低磷合金钢P22连铸管坯。     

Carbothermic Reduction of Nickeliferous Laterite Ores for Nickel Pig Iron Production in China: A Review

Both the consumption and production of crude stainless steel in China rank first in the world. In 2011, the nickel production in China amounted to 446 kilotons, with the proportion of electrolytic nickel and nickel pig iron (NPI) registering 41.5% and 56.5%, respectively. NPI is a low-cost feedstock for stainless steel production when used as a substitute for electrolytic nickel. The existing commercial NPI production processes such as blast furnace smelting, rotary kiln-electric furnace smelting, and Krupp-Renn (Nipon Yakin Oheyama) processes are discussed. As low-temperature (below 1300°C) reduction of nickeliferous laterite ores followed by magnetic separation could provide an alternative avenue without smelting at high temperature (~1500°C) for producing ferronickel with low cost, the fundamentals and recent developments of the low-temperature reduction of nickeliferous laterite ores are reviewed.     

Manganese Modification of the Fe-S-O System

A qualitative pseudoternary solidification diagram for the Fe-S-O system modified by manganese is proposed and supported by experimental derivation of an isothermal section at 1475°C and substantially 1 pct Mn in the solid-metal phase. The solubility of oxygen in liquid iron containing 1 pct Mn and sulphur contents up to 0.9 pct has been measured at 1600°C and found to increase as the sulphur content exceeds 0.15 pct.     

AN INVESTIGATION OF DEOXIDATION PROCESSES IN THE SMELTING OF RAIL-STEEL

本文结合生产,对鞍钢大型碱性平炉冶炼重轨钢的脱氧问题进行了试验。结果指出,在炉池内加脱氧剂进行预先脱氧的重轨成品含氧化物夹杂较少,尤以全部采用矽锰合金做炉池内脱氧剂的效果最佳,而在炉池内不加任何脱氧剂的重轨成品含氧化物夹杂量最多,后者往往超过前者一倍以上。重轨钢合硫一般达0.03—(0.04%,其中硫化物夹杂量与氧化物夹杂量相若,有时甚至达到后者的两倍。在这种情况下,决定钢的机械性能的主要因素是硫化物而不是氧化物,因此不同脱氧方法对重轨成品机械性能的影响不显著。在上述工作中,对重轨成品中氧化物夹杂的形状和大小也进行了分析,并指出在某些情况下铜液含氧量与铜成品中氧化物夹杂数量存在着相适应的关系。     

Einwirkung von Mangan in Stählen für die Strahlrohre in Pyrolyseöfen

Effect of manganese in steels used for radiation tubes in pyrolysis furnaces The effect of alloying elements on the extent of carburization in Cr25Ni35Nb steel used for radiation tubes in pyrolysis furnaces was investigated. It was possible to determine the role of minor manganese contents during carburization in a high carbon activity environment. Manganese contents up to 2.3% do not significantly affect the carburization intensity in carburizing environments without sulphur; the presence of silicon is more important (up to 2.5%) in these conditions. In sulphur-bearing environments better carburization resistance is obtained with steels containing less manganese (under 0,5%).     

热风冲天炉配加海绵铁代替废钢的生产实践

热风冲天炉熔炼低碳铁液,选择海绵铁代替废钢,在技术上可行,在生产实践中也满足了球铁管生产对铁液的质量要求,对球铁管主要质量指标没有不良影响,并取得显著的经济效益。冲天炉操作中要采取适当措施,使炉渣中的FeO含量不超过5％。     

80 t转炉提高废钢比的生产实践与炉况维护

转炉炼钢的主要原材料为废钢和铁水,由于国内外铁矿资源和优质焦煤资源的不断消耗以及节能减排的要求愈发严格,导致高炉铁水的生产成本提高,而废钢价格逐渐降低,故通过提高废钢比,降低铁水消耗量,以实现降低转炉炼钢消耗成本的目的。废钢提量后采用新的氧枪枪位控制、灵活加入轻烧白云石和石灰两种辅料、采用无烟煤作为热源提高转炉前期温度等方式后,钢厂最高吃废钢250 kg/t,平均出钢量为83.5 t,炉龄控制在14 000~17 000炉。     

Cementite transformation in low carbon steel under the influence of sulphur

Cementite/Fe₃C carbide in a commercial low carbon steel after prolonged service in naphtha environment with traces of sulphur of 0.3 ppm and at a temperature of 200–220°C has been examined. It has been stated that under the influence of sulphur, cementite at the steel surface and inside the steel is transformed into an unstable quasi‐crystalline phase enriched with sulphur/tramp elements and iron depletion. Cementite transformation and disintegration of the degraded carbide phase is connected with a release of carbon that diffuses into the steel in front of the sulphur diffusion zone. Beneath the steel surface a layer of low carbon content forms, followed by a zone of higher carbon content.     

熔铝用无芯工频感应炉炉衬寿命的探讨

石英砂固有良好的热稳定性,较高的机械性能,较小的热膨胀系数,价格低廉等优点,被广泛用做中小型感应炉的炉守材料,从工频炉熔炼铝合金的工艺特点及对材料性能要求着手,分析了石英砂颗粒配比,打结,烧结对炉衬寿命的影响,用于生产,取得了较满意的效果。     

HT300高强度缸体缸盖材料熔炼技术研究

分析了熔炼工艺、碳硅成分、锰硫成分、合金化及孕育处理对高强度灰铸铁铁液质量的影响,认为大量使用生铁使铁液收缩倾向增大且使铸件性能降低;增碳剂的选用是全废钢熔炼的关键;在较高碳硅含量条件下生产高强度灰铸铁件,必须设法在熔炼过程中增加石墨晶核,并增硫防止石墨长成粗大片状;适当的合金化和孕育处理,可以使铁液的收缩倾向得到明显改善。指出可以通过延迟开箱时间使铸件在砂箱中缓慢冷却以消除铸造应力,为生产优质铸件提供最后保证。     

HT300高强度缸体缸盖材料熔炼技术研究

分析了熔炼工艺、碳硅成分、锰硫成分、合金化及孕育处理对高强度灰铸铁铁液质量的影响,认为大量使用生铁使铁液收缩倾向增大且使铸件性能降低;增碳剂的选用是全废钢熔炼的关键;在较高碳硅含量条件下生产高强度灰铸铁件,必须设法在熔炼过程中增加石墨晶核,并增硫防止石墨长成粗大片状;适当的合金化和孕育处理,可以使铁液的收缩倾向得到明显改善。指出可以通过延迟开箱时间使铸件在砂箱中缓慢冷却以消除铸造应力,为生产优质铸件提供最后保证。     

高钒高速钢的冲击磨料磨损性能试验

以高铬铸铁(Cr26及高锰钢Mn13Cr2为对比材料,在MLD-10动载磨料磨损试验机上研究了高钒高速钢以鹅卵石为磨料时的冲击磨料磨损性能.结果表明,冲击功为0.5J时,高钒高速钢(V10)的耐磨性是高铬铸铁(Cr26)的2.1倍,是高锰钢(Mn13Cr2)的2.8倍.随13着冲击功的增大,高钒高速钢(V10)的耐磨性大幅下降,但其耐磨性仍高于高铬铸铁(Cr26)和高锰钢(Mn13Cr2).     

为铸造厂生产优质铸造生铁已刻不容缓

论述了优质铸铁件,特别是球铁、等温淬火球铁（ADI）和蠕铁件的市场需求及生产这些铸件必需的优质铸造生铁（包括高纯生铁）成分要求;指出优质铸造生铁大都是小高炉生产的,由于国家有关部门下令关闭200 m3以下的高炉,造成优质铸铁件必需的原材料缺乏危机;建议国家有关部门均衡考虑制造业中各行业的发展,有计划地落实铸造生铁,特别是优质铸造生铁和高纯生铁的生产和供应问题.     

Effect of Sulphur and Manganese on Nucleation of Corrosion Pits in Iron

Abstract

A study has been made of the effect of sulphur and manganese concentrations in iron on its tendency to pitting in a buffered potassium chloride solution. As revealed by electron microprobe and microscopic examinations, (Mn, Fe)S_x inclusions are the main sources of pit nucleation. Corrosion most frequently starts within the boundary region between the inclusion and the passive metal. Electrochemical investigations have shown that the critical pitting potential of the alloys under investigation, irrespective of S content, is lower than the corresponding value for ultra-pure iron. Mn has a dual effect on fhe resistance of Fe to pitting: it slightly increases the critical pitting potential, but it forms the sulphide inclusions at which the pits nucleate.     

The behavior of sulfur in industrial pyrometallurgical slags

Dissolution of sulfur in industrial slags, even at such a low level as 1 mass% S or so, increases the solubility of certain valuable metals by an order of magnitude. The phenomenon is accounted for in terms of Flood-Førland-Grjotheim’s model for dianionic salt solutions, whereas its rigorous analysis requires the digaseous Gibbs-Duhem integration. In the research described here, the distribution of sulfur among gas, slag, and metallic iron phases in the bath smelting of iron ore was computer-simulated based on a two-sites model coupled with sulfide capacity data. The solubilities of Ag, Cu, Co, and Ni in industrial slags are reviewed by applying the sulfidic-oxidic dissolution model to copper-matte smelting, nickel-slag cleaning (Falconbridge, Canada), and the imperial smelting process for zinc and lead (Hachinohe, Japan).     

包钢重轨钢从转炉出钢到结晶器过程中氢含量变化

研究了包钢重轨钢从转炉出钢到结晶器各个工序过程 (未经VD真空处理 )钢液中氢含量变化。工业实验结果表明 ,钢液增氢主要发生在转炉出钢过程中 ,大约占 75% ;其余发生在LF精炼过程。添加材料的水分和增强熔池中的搅拌程度对钢中氢含量影响很大 ,但钢中锰含量的增加对氢含量的影响不大。在包钢的气候条件下 ,季节和天气对钢水中氢含量直接影响不大。根据包钢重轨钢的冶炼条件 ,采用VD真空处理降低钢液中氢含量是完全必要的。     

Mn和Ce对Fe-Ni-Mn-C-Si-Ce系合金组织和性能的影响

采用熔炼法制备出新型高耐磨的Fe-20Ni-xMn-3.5C-2.5Si系固体自润滑材料,研究稀土元素Ce对Fe-20Ni-xMn-3.5C-2.5Si系合金中石墨的球化作用及Mn含量对力学性能及摩擦磨损性能的影响。结果表明：随着Mn含量的增加,合金凝固组织中奥氏体的硬度逐渐增大,特别是Fe-20Ni-xMn-3.5C-2.5Si-0.75Ce系合金在摩擦过程中的表面硬度大幅度提高,呈现出高锰钢特有的表面加工硬化性质,通过TEM可以观察到磨损表面生成孪晶型马氏体;添加0.75%（质量分数）的稀土Ce可以使结晶的石墨球化,使抗拉强度和抗弯强度大幅度提高,大约比未经球化处理的提高3～5.8倍;稀土Ce的加入可以促进Fe1.1Mn3.9C2型碳化物的生成,使材料的耐磨性进一步提高,其中Fe-20Ni-16Mn-3.5C-2.5Si-0.75Ce合金的磨损率最低,大约是QT500球墨铸铁的1/13。     

提高冶炼低硅含钛铁水转炉废钢比工艺攻关

废钢比是转炉生产的重要经济技术指标,其值大小直接影响转炉冶炼钢铁料消耗及热平衡,提高入炉废钢比是实现节铁增钢、降本增效的重要技术手段。然因冶炼低硅含钛铁水成渣难、脱磷难等问题,对应入炉废钢比持低不高,直接影响转炉生产成本。为此,基于低硅含钛铁水冶炼特点及难点分析,结合水钢生产实践,通过氧枪喷头优化、枪位优化、添加提温剂等工艺优化和技术开发,使入炉废钢比由优化前7.41%提高至13.48%,优化效果较为明显,为实现节铁增钢、降本增效奠定了一定基础。