Acid Open Hearth Research Articles

ガス撹はんによる取鍋精錬法「ＬＦ法」の開発経緯と現状 酸性平炉法で得られた知見の一展開

ガス撹はんによる取鍋精錬法「ＬＦ法」の開発経緯と現状 酸性平炉法で得られた知見の一展開

The effect of residual gas content on the performance of rolling bearing materials

Using an accelerated service simulation test the effect of gas content on the performance of ball bearing steels has been assessed. The results together with the findings of metallurgical investigations of failed specimens help to explain the significant effect of the steelmaking and refining process and manufacturing variables in rolling contact fatigue resistance and the correlation between this and resistance to cavitation erosion. Hydrogen pick up and hydrogen embrittlement are contributory environmental factors in a specific type of premature failure. Oxygen content is mainly associated with non-metallic inclusion, the morphology of which is the important feature. Interstitial nitrogen and nitrides can pin dislocations to delay stress relaxation and recrystallization and can account for the difference in behaviour of acid open hearth (AOH) and basic electric arc (BEA) steels and the varied performance of ball bearing steels in general. It is suggested that a principal factor in the production of high quality ball bearing steel is the reduction of residual nitrogen.

The role of nitrogen content on the rolling contact fatigue performance of En31 ball bearing steels

Using an accelerated service-simulation test, the role of nitrogen content on the rolling contact fatigue resistance of a range of En31 ball bearing steels was assessed. Nitrogen content appears to be a significant factor in steel performance. Air-melted neutral open hearth and acid open hearth materials, which were superior to air-melted basic electric arc steels, were comparatively low in nitrogen. With the basic electric arc materials there was a trend towards reduced rolling contact fatigue life with increased nitrogen content.

Hardness changes in rolling contact—their significance in ball-bearing steel performance

Analysis of hardness changes has revealed significant differences which explain the variation in performance in rolling contact between samples of basic electric arc (BEA) ball-bearing steels and the difference between BEA and acid open hearth (AOH) material. It is suggested that the BEA steels inhibit the spread of strain hardening, and these steels are therefore less resistant to rolling contact fatigue than the AOH steels. Interstitial nitrogen content may be a contributory factor and could explain differences between otherwise identical casts of BEA steel.

Oxygen in Steel Refining as Determined by Solid Electrolyte Techniques

These illustrations are typical of the results which have been obtained by use of the O-Probe in acid open hearth steels. It is obvious that the probe can provide valuable information to the operator while the steel is still liquid.

The Rapid Determination of Oxygen in Commercial Steel with the Solid Electrolyte Probe

A review has been made of all induction furnace, acid open hearth, and electric arc furnace heats which have been studied in this investigation. It has been concluded that one should not expect the vacuum fusion tests always to coincide with the indications of the solid electrolyte method, unless under closely controlled laboratory conditions.

Deoxidation and alloy recovery in acid open hearth practice

Deoxidation and alloy recovery in acid open hearth practice

The effect of chromium in the charge on the operation of the acid open hearth

The effect of chromium in the charge on the operation of the acid open hearth

塩基性電弧炉および酸性平炉溶製の20t鋳塊ならびに真空鋳造製20t鋳塊の非金属介在物

塩基性電弧炉および酸性平炉溶製の20t鋳塊ならびに真空鋳造製20t鋳塊の非金属介在物

Thermal aging characteristics of bottom sands in acid open hearth furnaces

It may be that an understanding of the development of a liquid phase from the disordered silica upon the surface of new sand grains and the development of the liquid transition phase from crystalline quartz will lead to improved operation in acid open hearth furnaces. The existence of such liquid phase appears to have a relation to the formation of gas cavities in steel castings and possibly contributes to the phenomenon called metal penetration.

A Comparison of Charpy and Izod Impact Testing in Acid Open Hearth Steels

Charpy and Izod V-notch specimens of three low alloy steel casting grades were tested as a function of temperature. For any given set of conditions of testing temperature and composition, the Izod impact values were consistently higher. The transition temperature, as measured by various criteria, was considerably lower for Izod than for Charpy when relatively tough materials were tested. In brittle materials the Izod and Charpy transition temperatures are both quite high. Depending on the method of determination, the Izod transition temperature can be either higher or lower than the Charpy transition temperature.

塩基性電気炉および酸性平炉溶製の大型鍛鋼材に関する比較検討ならびに真空造塊に関する研究

塩基性電気炉および酸性平炉溶製の大型鍛鋼材に関する比較検討ならびに真空造塊に関する研究

鋼浴中の酸素分析試料採取法に関する研究

The method of taking a sample for determination of the oxygen in steel fresh from the furnace has not yet been established, although it has been the target of discussions.This report treats of the results of the study conducted on vacuum sampling method which is almost perfect and comparatively simple in operation.The sampler for vacuum sampling method is as shown in Fig. 3 and 4 and Photo. 1, and suction tube of the sampler has been made vacuous with its tip prepared as shown in Fig. 1In case of determining oxygen content in steel in an acid open hearth furnace, vacuum sampling method has been closely similar with bomb method but apparently different from casting method, which has generally shown higher value.While in case of a basic open hearth furnace, vacuum sampling method has shown a lower value than the cases of bomb method, suction method and casting method.It is diffiicult to draw a conclusion from the experimental results because the amount of gas released during solidification of molten steel is variable with its chemical components, temperature and solidification condition. It is presumed that some amount of gas may be released when carbon content in molten steel is medium and silicon and manganese contents are low, but in most cases the amount of gas released has been within analytical error.

Hydrogen in steelmaking practice

Based on a rapid analytical procedure for hydrogen and a reliable sampling method for obtaining specimens from a molten steel bath, a series of three acid open hearth, two basic open hearth, and seven basic electric furnace heats were examined through the refining period, at tap, and in some instances during pouring for variations in hydrogen content. Experiments and calculations are presented to show that the measured hydrogen content is the result of two competing processes, one of which drives hydrogen into the metal from the gas and slag phases and the other eliminating hydrogen through the CO boil. Hydrogen absorption rates are calculated to show the differences which exist among the acid and basic open hearth processes and the basic electric process.

酸性平炉と塩基性電気炉で溶製した軸受鋼について

酸性平炉と塩基性電気炉で溶製した軸受鋼について

軸受鋼の研究(III)

There are two kinds in the steel-making process of the ball bearing steels, namely, small acid open-hearth and basic electric-arc process.The former is adopted mostly in SKF Hofors Bruks, and the latter is the process which is used mostly in Japan and U.S.A.Therefore, the austenitizing behaviour of the above kind ball-bearing steels, made in Japanese steel maker and tubings of SKF bali bearing steel is studied and reported in this paper.The steels, made by the acid open hearth and the basic electric arc process, have the different quenching-sensibility. According to this sensibility, the difference of change in the hardness and the mechanical property is barely, but the ease, with which the cementite goes in solution in the austenitizing state, is very different by the above two kind of process.Namely, the cemente in the electric arc furnace steel goes in solution easily, but it does not go in solution easily under 850°C temperature and goes in solution easily and rapidly above 850°C temperature in the open hearth furnace steel.Secondly, although there are many non-metallic inclusions in SKF tubings of ball-bearing steels, these steels are stable in the austenitizing state, and the quenching sensibility of this steels is dull.This relates to the solution speed in the cementite, and the solution of it is stable comparatively from 800°C to 880°C temperature.

Some Observations of Slag-Metal Relations In the Acid Open Hearth Steel Furnace

Trends in slag composition in acid open hearth practice, particularly the variation in iron and manganese oxides during refining, are reviewed. A procedure which is currently being used to control the refining reactions is described and partially explained through slag phase diagram considerations. In addition, the ionic nature of these slags is considered and it is proposed that silica combines with the oxide ion and forms a series of complex silicate ions. The effect of basic oxides such as FeO, MnO, and CaO is apparently additive in furnishing the oxide ion for this purpose.

發生爐瓦斯平櫨に於ける燃燒に就て(III)

The authors could establish a method of discriminating the real state of gas combustion in an open hearth furnace by means of taking gas from some spot in the gas flame and analizing its chemical contents. By this method the following results were obtained in consequence of the experiments with respect to Venturi type acid open hearth furnace (nominal capacity 40t).(1) The velocity of gas combustion in the open hearth furnace was quantitatively measured by the variation of the quantity of CO content in the flame gas.(2) The combustion velocity is increased by the addition of air blowing and fat more in creased by the addition of oxygen blowing compared with that of gas only.(3) The combustion velocity was compared as follows by finding out the gas combustion velocity constant (K) in an open hearth furnace.(i) In the case of ordinary operation (gas only, excess air 15%)…K≅13(ii) With the addition of air blowing (4m3/min)…K≅37(iii) With the addition of oxygen blowing (7m3/min)…K≅66

發生爐瓦斯平爐に於ける燃燒について (I)

By utilizing oxygen as an accelerating agent for the producer gas combustion in the open hearth furnace, the melting time can be shortened, and steel production rate increases. But the high cost of oxygen at present prevents the applicaion of oxygen into daily practice generally, therefore in place of oxygen compressed air was used and the comparison tests of both effects on shortening the melting time by the Venturi type acid open hearth furnace (Nominal capacity 40t) was performed. As the results, the melting time was shortened by 14% by use of oxygen and was shortened by 13% by use of compressed air. And the fuel comsumption during the melting period is saved about 10% by use of oxygen or compressed air.

物理化學より見たる平爐操業諸過程の關連性について(VII)

How the steel bath becomes not gasious in final period of melting process, and how the steel bath gets the standard amount of Si, Mn, C are discussed.Thus the five objects to remelt steel scrap are all obtained. From the first report to the seventh report, the mutual correlation of the entire procedure in the acid open hearth process is physically and chemically analysed, and we knew that the whole operation which is systematised with the accumulation of experiences is generally reasonable and we are obliged to pay our respects to our senior's merit.