上海申佳铁合金有限公司成功开发两种优质特殊钢用铁合金

专业从事铁合金生产的上海申佳铁合金有限公司成功开发了低钛高碳铬铁和高纯铬铁两个新品种 ,为高质量特殊钢生产提供了保证。低钛高碳铬铁含钛量很低 ,用于冶炼轴承钢可有效减少钢中Ｔｉ (Ｃ ,Ｎ)杂质 ,提高钢材使用寿命。高纯铬铁具有主元素高 ,硫、磷等杂质元素低的特点 ,是微碳铬铁系列中的新品种。由于纯度高 ,可部分替代金属铬应用于冶炼不锈钢、镍基合金等特殊产品。采用热兑工艺实现工业化生产高纯铬铁在我国是首创上海申佳铁合金有限公司成功开发两种优质特殊钢用铁合金@陈兴章     

负压吹氧制中低碳铬铁

一、前言冶金用氧及低压冶金在工业上推广应用之后,使产量和质量显著提高。铁合金工业上曾引进这项技术,使精炼产品强化脱硅,缩短冶炼时间,及用低压制取微碳、超微碳铁铬,金属铬、金属钒等。铁合金生产上通常用碳素还原,制碳素铁合金;用硅合金还原,制中低碳铁合金,因为硅化物强于碳化物。目前就中低碳铬铁生产看来,有电硅热法和热兑混炼法二种。电硅热法若能普遍采用热装和精炼末期吹氧脱硅,则可以使单位产品电耗大为降低,但     

生产镍铬复合烧结矿及镍铬铁合金的研究与实践

为实现铬精粉矿、红土镍矿复合烧结及用该复合烧结矿冶炼镍铬铁合金,有针对性地对铬精粉矿、红土镍矿的相关物理性质和镍铬复合烧结固结机理进行了研究,并结合实验室得出优化配比结果,在烧结生产实践中进一步探索,达到优化方案,降低煤耗20.6%、动力电32.8%,降低了烧结成本,提高质量。同时,介绍了用镍铬复合烧结矿冶炼镍铬铁合金的生产实践,在生产实践中总结得出冶炼工艺经验数据:电炉变压器容量范围为12.5～33 MVA的矿热炉,操作电阻为1.5～1.7 mΩ。采取一些技术措施后,成功实现镍铬铁合金生产,铬回收率93.2%,镍回收率94.7%,冶炼电耗3 449 kWh/t,效果较好,经济效益可观。该镍铬复合烧结工艺及用复合烧结矿冶炼镍铬铁合金得到产业化应用,取得一定成效。     

含铌钢用铌铁矿 微合金化试验

用铌铁矿代替铌铁合金,在电炉冶炼20MnSiNb钢时进行微合金化,在冶炼操作工艺只作小的调整情况下,铌的回收率可达70～90％,比用铌铁合金费用降低近20％。本试验尚属初步探索,还有一些技术工艺问题,有待今后研究解决。     

等离子炉冶炼钼铁合金

一、前言目前等离子技术在铁合金生产中的研究及应用主要有二个方面:一是用等离子炉代替矿热炉冶炼铬铁、锰铁和硅铁等铁合金产品,在这方面表现出来的主要优点是可以利用粉矿和非优质还原剂;二是应用等离子技术冶炼一些特殊铁合金,如钨铁、钼铁、铌     

电炉炼钢过程铁合金的节约

现代技术对合金的质量提出更高的要求。合金钢和高合金钢等新的钢种在不断地出现。这些钢的生产在逐年增长。因为铁合金在很大程度上决定了金属的成本,因此,在大批冶炼的条件下降低铁合金的消耗就具有重要的意义。用氧气重熔合金钢废料是降低铁合金消耗的最有效措施。目前仍继续探讨用合金钢废料重熔方法冶炼新牌号钢和合金:用铌合金化的高锰铝钢、铬锰钢及其它钢种。     

油气田用Inconel718合金腐蚀性能研究综述

综述了油气田用Inconel 718合金抗均匀腐蚀、点蚀、晶间腐蚀、电偶腐蚀、氢脆和应力腐蚀等常见腐蚀性能,分析了Inconel 718合金耐蚀性能良好的主要原因,着重阐述了Inconel 718合金热处理工艺对各种腐蚀行为的影响,并提供了合理的热处理工艺对应的安全服役环境。最后展望了高温高压含H2S腐蚀环境下Inconel 718合金的选材依据、应用前景,以及Inconel 718合金性能提高的热点和难点。     

新书介绍

《铁合金》编辑部经近一年的努力,将创刊近200期的《铁合金》杂志重新进行了分类整理,编辑出版了各种铁合金生产工艺专集,具体价格详见本刊第53页,部分专集目录如下:《高碳铬铁生产工艺专集》目录一、生产工艺电热-燃料热法溶炼碳素铬铁用预还原球团生产高碳铬铁的矿热炉操作及控制铬矿球团预还原及冶炼碳素铬铁的半工业试验     

激光近净成形Inconel 718高温合金的力学性能与耐腐蚀性能

以气雾化Inconel 718高温合金粉末为原料,采用激光近净成形增材制造技术制备用于酸性油田密封件与管道的Inconel 718合金,然后采用2种不同工艺进行热处理。通过扫描电镜与透射电镜观察、拉伸试验以及电化学腐蚀试验,对该合金的组织、力学性能和耐腐蚀性能进行分析和研究。结果表明:激光成形沉积态Inconel 718合金的主要缺陷为空心颗粒和氧化物颗粒,合金具有优异的抗腐蚀性能,但力学性能较差,抗拉强度为866.9 MPa。经过热处理后,由于γ″和γ′复合强化相的析出,合金的抗拉强度明显提高,伸长率降低。其中经均匀化+固溶+双时效处理的合金具有更优异的力学性能,抗拉强度达1 211.9 MPa,满足油田密封件管道的性能要求,且腐蚀性能优于目前用于酸性油田的轧制态Inconel 718高温合金。     

8000KVA铁合金电炉液压系统使用情况

前言我厂8000KVA 矿热电炉是我国自行设计、制造的第一台封闭式炉体旋转的铁合金电炉,于1965年设计,1968年投产。最初是用于冶炼一种铁合金的新工艺试验,1972年下半年改炼炭素铬铁和硅铬合金。     

A comparative evaluation of low cycle fatigue behavior of conventional and modified INCONEL 718

Structural stability of the Inconel 718 is reported to enhance at temperatures above 650°C, with increase in Al/Ti and Al + Ti/Nb atomic ratios. However, no report is available on low cycle fatigue behavior of the modified compositions of the Inconel 718. The present investigation deals with comparative study of LCF behavior of the conventional and modified 718 with Al + Ti/Nb ratios of 0.294 and 0.459 respectively at 650°C. It was observed that fatigue life of the modified alloy, in terms of Coffin-Manson relationship was higher than that of the conventional one.     

Elemental Partitioning Characteristics of Equilibrium Phases in Inconel 718 Alloy at 600-1100 ℃

 The optimization of heat treatment and chemical composition for Inconel 718 alloy has been investigated uninterruptedly because of its excellent mechanical properties and metallurgical workability. The species, chemical compositions and content of equilibrium phases of Inconel 718 alloy in the temperature range of 600-1100 ℃ were calculated by using thermodynamic software “Thermo-Calc” and the latest relevant datebase of Ni-base superalloys. A concept of elemental partitioning fraction was used to study the partitioning characteristics of alloying elements in each equilibrium phase at different temperatures, such as Ni, Cr, Fe, Nb, Mo, Al, Ti and C, and some calculation results were confirmed under a scanning transmission electron microscope (STEM). The results showed that the elemental partitioning characteristics with the change of temperature revealed the selective partitioning characteristic of alloying elements in equilibrium phases at different temperatures, such as Nb was mainly distributed in δ and γ′ phase, C in carbides, Al and Ti in γ′ phase and Cr, Mo in Laves phase. At the same time, the effect of the change of component and quantity for each precipitated phase on matrix phase can be helpfully understood, which provided a theoretic foundation to optimize the chemical composition and heat treatment in different environments for Inconel 718 alloy.     

制粉方法对Inconel718合金粉末组织和性能的影响

以Inconel718合金为研究对象，分别采用等离子旋转电极法（PREP）和气体雾化法（VIGA）制备了金属球形粉末，研究了不同制粉方法对粉末在热处理前后的组织和成分分布的影响，采用对流热交换原理对两种制粉方法对应的冷速进行了模拟计算。分析结果表明：采用PERP法制备的Inconel718合金粉末在氧增量、球形度及流动性方面具有一定的优势，而VIGA法制备粉末有利于提高粉末的显微硬度、细粉粒径；两种粉末经过相同的热处理工艺后，其组织变化规律相同，均析出富Nb和Mo相。模拟计算结果表明：VIGA法制备细粒径粉末的冷速明显高于PREP法对应的粉末，与实验对应的性能数据结果相吻合。     

Structure of Vacuum Brazed BNi-5 Joint of Inconel 718

Structural investigations of the brazed joint of Inconel 718 with BNi-5 filler metal were carried out on specimens with geometries simulating a real joint. Three identification methods applied in parallel were used. Fused and solidified filler metal showed the presence of at least four microstructural components: the dominant γ-solid solution, two binary eutectics (G phase + γ) and (θ-phase + γ@#@), and prismatic objects identified as cr-phase. The influence of brazing time and temperature was studied with specimens heated in accordance with three different thermal regimes. The Ni-base γ-phase solidifies in dendritic form and contains Cr, Fe, Nb, and Mo, the concentrations of which are dependent on the thermal regime and on the distance from the former liquid-solid interface. The intermetallics (G, 0) and the matrix form binary and ternary eutectics. In overheated brazed joints the filler metal penetrates into the grain boundaries of the base metal, resulting in the formation of new phases. The dominant phase was identified as a hexagonal Laves phase (λ,). The diffusion zone in the base metal can be divided into two subregions. In subregion I the precipitating phase is a Nb-rich G-phase, while in subregion II, the depth of which can be directly related to the width of the gap, preferentially oriented carbides of Nb and Ti are formed. The phase formation in the BNi-5 brazing of Inconel 718 may be described by a quasi-quarternary diagram on the Ni-Cr-Nb-Si system.     

Laser Direct Metal Deposition Technology and Microstructure and Composition Segregation of Inconel 718 Superalloy

  Multilayer of laser direct metal deposition (DMD) was prepared by depositing a gas atomized pre alloyed powder with a composition close to Inconel 718 alloy on Inconel 718 high temperature alloy substrate. The effects of the DMD parameters on the build up rate and the structure of the deposited layer were studied. The laser DMD sample was further processed by a solution treatment. The microstructure and property of the laser DMD zone before and after heat treatment were investigated as well. The results show that the laser parameters of actual laser power of 650 W, scanning speed of 58 mm/s, beam diameter of 1 mm, powder feed rate of 645 g/min, with a corresponding specific energy of 90-130 J/mm2, can be recommended as optimum parameters for high build up rate of Inconel 718 alloy. Under the condition of optimized parameters, a directional solidification microstructure was obtained and the average distance between the columnar crystals was 5-10 μm. The microcomposition segregation was found between the columnar crystal trunk and columnar crystal. The elements of Nb, Mo, Ti concentrated in the columnar crystal trunk. After the heat treatment, the segregation was greatly minimized, and the segregation ratios were close to 1. The hardness of the laser deposited layer did not show obvious difference along the height of the layer either for the as deposited layer or for the heat treated layer. However, the microhardness of the laser DMD zone after heat treatment was obviously higher than that after the as deposited treatment. During the heat treatment process, some Nb and Mo rich phases precipitated and strengthened DMD layer.     

包头铌铁矿冶炼实验研究

针对包头矿高铁低铌的特点提出了选择性还原-熔分-铌铁冶炼的处理方案,并对方案的三个关键步骤进行了实验研究。结果表明,熔分阶段铌回收率在95%以上,冶炼阶段铌回收率在85%以上,全流程铌回收率>80%,铌磷Nb/P>15。本流程完全可综合回收包头矿中的铌、铁、锰等元素。     

Observations of melt rate as a function of arc power,CO pressure,and electrode gap during vacuum consumable arc remelting of Inconel 718

Statistically designed experiments were conducted at two different production melt shops to evaluate the influence of arc power, CO pressure, and electrode gap on melt rate. Approximately 11,000 kg of Inconel 718 alloy 0.4 m diameter electrodes were vacuum consumable arc remelted into 0.5 m diameter ingots. Analysis of the experimental results revealed that melting efficiency (melting rate/kW) was maximized when CO pressure and electrode gap were held at low levels. Under these conditions, the heat distribution (created by the vacuum arc) on the electrode tip and the molten pool exhibited macro uniformity. Increased CO pressure and/or electrode gap depressed the melt rate, and at 13.3 Pa (100 microns) and a 0.050 m electrode gap, this depression exceeds 46 pct. Increasing these parameters also changed the arc behavior to that of a constricted arc with a highly localized heat input. It is hypothesized that the change from the usual diffuse arc to this constricted arc results in intense Lorentz pumping in a localized region of the molten pool atop the ingot causing fluid flow transients. These transients could, in turn, create solidification defects.     

Electromagnetic stirring with alternating current during electroslag remelting

An alternating current (AC)-operated electromagnetic stirring (EMS) device, using line frequency, was designed and built to operate on a laboratory electroslag remelting (ESR) furnace for 150-mm-diameter ingots. Laboratory-scale experiments were conducted employing both 4340 alloy steel and INCONEL 718 alloy as electrode material. The initiation of stirring is accompanied by a thin strip of segregated material and favors the formation of spot segregation. Changes produced in the fluid flow conditions in the liquid pool ahead of the solidification front result in a transition from a highly directional columnar to an unoriented, branched structure. Except for small pockets of segregated liquid, the flow of molten metal does not penetrate into the mushy zone. Both electrode material and molten metal pool shape play an important role on the extent of promoting an equiaxed structure.     

Recrystallization and aging effects associated with the high temperature deformation of waspaloy and inconel 718

Cylindrical samples of Waspaloy and Inconel 718 were hot compressed, using a computerized Instron machine. The test program covered strain rates from 10^•4 s^•1 to 1 s^•1 temperatures ranging from 875 °C to 1220 °C and deformations up to strains of 0.7. Interrupted tests were also carried out to determine the nature of the static softening and hardening processes. Dynamic recrystallization, partial or complete, was observed at temperatures above 950 °C. At 950 °C and below, dynamic recovery was the process controlling the deformation. Static softening was found to take place both by recovery and by recrystallization. Yield points were detected in Waspaloy under certain conditions as well as in Inconel 718. For Waspaloy the yield drops occurred in the vicinity of 1100 °C, and a deviation from the normal behavior in the stress-temperature curve was seen in the same temperature range. The mechanism responsible for the occurrence of the yield drops, which in turn is related to the deviation in the σvsT curve, is believed to be short range ordering of the γ’ forming elements. For Inconel 718, elements such as Co, Cr and Fe may be causing short range ordering, but the locking mechanism may also be associated with the precipitation of carbides or other intermetallic phases on the dislocations.     

Structure of chromium-rich Cr-Ni,Cr-Fe,Cr-Co,and Cr-Ni-Fe alloy particles made by evaporation in argon

Structural analyses were performed on alloy particles of chromium-rich Cr-Ni, Cr-Fe, Cr-Co, and Cr-Ni-Fe systems. Fine alloy particles (100 to 1000Å in diameter) were prepared by evaporation of parent alloys in argon at 20 torr. In addition, alloy structures of bulk specimens of the Cr-Ni system were investigated using X-ray diffraction techniques to confirm the results obtained from the particulate alloys. In these binary systems, δ phase with W₃O structure (A-15) and a phase withβ-uranium structure (D _b ⁸ ) were identified in addition to the α (bcc) and γ (fcc) terminal solid solutions. The compositional ranges for the σ phase in the Cr-Ni, Cr-Fe, and Cr-Co systems are from low chromium to 68, 63.4, and 62.1 wt pct Cr, respectively. The δ phase exists in the range from pure chromium to 68, 58, and 54 wt pct Cr in the respective Cr-Ni, Cr-Fe, and Cr-Co alloy systems. Similarly, in the Cr-Ni-Fe system, it was found that δ phase occurs in the chromium corner while σ phase exists in the region bridging the two binary σ phases of the Cr-Ni and Cr-Fe systems. Possible modification of phase diagrams of these systems is discussed in view of these results.