电炉钢的快速冶炼

在电炉钢的冶炼过程中，熔化期是非常重要的一部分，占到整个电炉冶炼时间的一半，耗电要占三分之二。因此，要实现电炉钢的快速冶炼，熔化期的优化工作尤为重要。通过对电炉冶炼熔化期炉料的熔化及物化反应的分析研究，得出以缩短熔化期来实现电炉钢快速冶炼的结论，主要介绍了在熔化期强化冶炼操作，缩短熔化期冶炼时间的各种方法。另外，在熔化期尽快造渣脱磷能减轻氧化期任务，从而进一步缩短电炉冶炼时间。     

电炉炼钢工艺改革生产总结

多年来我厂炼钢基本工艺的主要特点是“三期”操作:即熔化期,氧化期,和还原期(以下简称老工艺)。氧化期采用矿石加氧气氧化,还原期采用传统的扩散脱氧方法。因此冶炼时间长,能源消耗高,生产效率低,严重影响了经济技术指标的提高。为生产出物美价廉的产品,加快四化建设,改革炼钢基本工艺势在必行。随着炼钢生产实践的发展,电炉炼钢理论的研究,新技术新设备的采用,人们对电炉炼钢基本规律的认识,也在不断深入,因此对电炉炼钢基本工艺改革条件已经成熟。今年初抚顺钢厂与北京钢铁学院合作,对老工艺进行剖析,围绕改革老工艺开展了试     

真空熔炼K417G合金脱氧脱氮研究

分析了采用真空感应炉熔炼镍基高温合金K417G过程中熔化期、精炼期和合金化期对氧氮气体含量的影响。研究表明:熔化期主要脱除氧,其次是氮;精炼期添加碳,合金化期添加铝,能够很好地降低合金氧氮含量,使合金中O≤10×10~(-6),N≤5×10~(-6)。     

煤氧枪强化电弧炉冶炼的试验研究

本文结合生产,在唐钢铸钢厂的5吨电弧炉上进行了煤氧强化电炉冶炼的工业性试验。冶炼20MnSi钢44个炉次的结果表明,采用煤氧强化电炉冶炼,可缩短熔化期时间20～30分/炉,降低熔化期电耗70～100度/吨钢,缩短全程冶炼时间20分/炉,降低全程电耗70度/吨,冶炼总成本约降低4％。     

电炉变压器的保护定值计算

电炉冶炼熔化期电极及炉料或电极周围的炉料塌落而使电极二相或三相短路。电炉变压器在熔化期点弧及塌料时经常处于连续短路状态,这种工作短路是不可避免的,是正常现象。所以电炉变压器必须满足这一要求,但又必须采取措施,使工作短路电流的倍数和持续时间不超过规定值。根据冶炼工艺的要求和电炉电气设备标准规定,工作短路电流要小于3～3．5倍电炉变压器额定电流,持续时间小于6s,短路速断电流小于4—6倍电炉变压器的额定电流,持续时间0s。     

采用锈蚀纯铁在真空感应炉内炼钢的可行性分析

为拓宽真空感应炉用料范围,采用锈蚀纯铁和洁净纯铁在相同条件下进行熔炼对比实验,结果表明,采用锈蚀纯铁钢中夹杂物最高含量为2.5级,采用洁净纯铁钢中夹杂物最高含量为1.0级,夹杂物主要为炼钢过程中生成的Al2O3和球状铝尖晶石.通过改进工艺,利用碳在真空状态下脱氧能力比Al强的特点,在熔化期和精炼期深度脱氧减少钢液中Al2O3夹杂的含量,解决了锈蚀纯铁在真空感应炉内炼钢造成的合金损耗大、夹杂物偏高等问题.     

H13模具钢切削废屑回收处理工艺对合金元素回收率的影响

为对H13模具钢切削废屑加以回收利用,提高Cr、Mo、V等合金元素的回收率,采用50 t中频感应炉-LF-VD流程对切削废屑进行返回法熔炼H13钢。分析了固化压块和低真空熔化工艺对Cr回收率的影响和CaO-BaO复合渣系BaO含量对脱磷效果的影响。结果表明,对废屑进行固化成块处理、采用≤1 333 Pa低真空熔化,可以将废屑中Cr、Mo、V的回收率提高到96%以上,与用未压制的切削废屑熔炼相比,节约熔化时间25 min/炉,在熔化期采用高碱度的CaO-20%BaO复合渣系进行除磷,可以将产品中P含量控制在0.01%。     

在各种渣成份下电弧炉熔池中含氮量的变化

在电弧炉熔化期采用石灰石代替石灰造渣,钢水的脱碳条件,还元期渣的成份,钛铁的加入,采用酸性炉衬,往熔池中吹入气体—这些因素都对氮气脏污钢的程度有影响,但在很多情况下,对高碳钢及低碳钢的影响是不同的。     

采用锈蚀纯铁在真空感应炉内炼钢的问题分析

为拓宽真空感应炉用料范围,采用锈蚀纯铁和洁净纯铁在相同条件下进行熔炼对比实验。实验结果表明,采用锈蚀纯铁和洁净纯铁钢中夹杂物最高级别分别为2.5级和1.0级,夹杂物主要为炼钢过程中生成的Al2O3和球状铝尖晶石。通过改进工艺,利用碳在真空状态下脱氧的能力比Al强的特点,在熔化期和精炼期深度脱氧以减少钢液中Al2O3夹杂的含量,解决了锈蚀纯铁在真空感应炉内炼钢造成的合金损耗大、夹杂物含量偏高等问题。     

电弧炉加块煤节电研究

电炉装料时将块状烟煤加入炉内,吹氧的同时吹入压缩空气,利用煤燃烧放出的热量可部分代替电孤热加热废钢。本文通过试验研究了煤的不同加入量、加入方式、供氧强度、吹氧方式、装料次数等诸因素对冶炼时间及电耗的影响,加块煤冶炼工艺与通常工艺相比,熔化期时间约缩短40min.每吨钢每公斤煤节电4kWh左右.     

Refining by fractional melting

A new and highly effective method of purifying metals is described. The process, a fractional melting process, involves heating an alloy within its liquid-solid region while simultaneously compressing it against a filter to remove the interdendritic liquid. A simple mathematical model is developed_which shows that remarkably high “refining ratios”, ˉC_c/C_o, can be obtained (where ˉC_c is wt pct solute of the refined “cake” and C_o is initial wt pct solute). For example, for a “yield” of refined solid of 0.4 of the original sample and a partition ratio,k, of 0.1, this new process achieves a refining ratio of as low as 10⁻⁴, 1000 times lower than isothermal separation and comparable to that obtained by multi-pass zone refining. Refining ratio is shown to depend on partition ratio, “instantaneous cake wetness” during the refining process, final fraction solid and extent of diffusion in the solid. (“Instantaneous cake wetness” is defined as fraction liquid in the cake at any given instant during refining.) Refining experiments were conducted on a series of Sn-Pb alloys in which samples were heated under a pressure of 21 MPa (2900 psi), over a temperature range of 5 to 20°C above the eutectic temperature. Refining ratios obtained are in agreement with theory, assuming low “instantaneous cake wetness”. Calculations showed this wetness to be about 0.02. Final structures of the refined solid are fine grained and completely devoid of second phase. This paper is based on doctoral thesis work of A. L. Lux.     

Local melting in Al-Mg-Zn-alloys

The internal melting of several Al-Mg-Zn-alloys has been studied by rapid upquenching in a salt bath of specimens slowly cooled at a rate of 2 °C/h down to 375 °C. The melting reaction was studied metallographically in the light- and electron-scanning microscope, and local concentrations were measured in the microprobe. Local melting of both the equilibrium phasesT and η was observed to occur. There were, however, essential differences between the melting kinetics for the two phases. While theT-phase particles melted spontaneously at temperatures at or above the invariant temperature, 489 °C, and after some period of time at lower temperatures, the η-phase particles either melted spontaneously at or above the invariant temperature,T - 475 °C, or dissolved into the matrix at temperatures below 475 °C. This difference in behavior can be accounted for if the α(Al)-η section is not a quasi-binary section. The industrial implications of the internal melting in these alloys are discussed and compared to the same reaction in the Al-Mg-Si alloys. A model is developed in the Appendix to quantify the different behaviors of these two classes of alloys.     

稀有金属真空熔炼熔速控制的研究

针对电弧炉的不稳定性和强耦合性问题,提出一种基于模糊控制真空自耗电弧炉熔速控制方法,通过对熔速控制系统模型分析与描述、对真空自耗电弧炉熔速控制策略分析以及对模糊控制理论的研究,实现对电弧炉熔速的稳定控制,从而保证真空自耗电弧炉的稳定性运行。     

Formation of local melting regions in a solid body near the melting temperature

The formation of local melting regions is shown to be ensured by the fluctuation of the vibrational (kinetic) energy in a crystal. This approach is based on the Frenkel’ idea about heterophase fluctuations. Equations that relate the additional volume (ΔV(T)), electrical resistivity (Δρ(T)), or enthalpy (ΔH(T)) increment in solids to the presence of local melting regions are obtained. An analysis of the experimental data demonstrates that 6% of the solid body atoms have the properties of a liquid at the melting temperature. This approach is used to explain some unexpected facts and to calculate the energy of formation (E _f) and concentration (C _m) of vacancies in some metals.     

Pressure dependence of collagen melting

Calf skin collagen type I and interstitial collagen of the annelids Alvinella pompejana and Riftia pachyptila were thermally unfolded at pressures of 1 and 200 bar. The high pressure was near the habitat pressure of the annelids which live in deep sea hydrothermal vents. The transition temperature increased with pressure by only 1.4 +/- 1 degrees C for calf skin collagen, and no pressure effect was detectable for the annelid collagens. The value for calf skin collagen agrees with prediction based on published values of the transition volume and transition enthalpy. The triple helices of the interstitial collagens of the annelids, which have melting temperatures of 46 degrees C (Alivinella pompejana) and 29 degrees C (Riftia pachyptila), are not further stabilized by pressure.