Oxide Inclusions In Steel Research Articles

Oxide inclusions in steel

Oxide inclusions in steel

Oxide inclusions in steel

Oxide inclusions in steel

カルシア質電弧炉炉床の実用化と酸化物系介在物への影響

カルシア質電弧炉炉床の実用化と酸化物系介在物への影響

上注高炭素クロム鋼の製鋼過程における酸化物系介在物の挙動について

In order to investigate the source of oxide inclusions, variation in the composition and the microscopic structure of oxide inclusions in steelmaking process of top-teeming high carbon chromium steel were investigated.In addition, oxide inclusions in ferrosilicon and effect of the use of low aluminium ferrosilicon on oxide inclusions in steel were also investigated.The results were summarized as follows.(1) It was found that spinel (MgO·Al2O3), a main constituent mineral of oxide inclusions, was produced by mutual reaction of deoxidation product formed by Al or aluminate inclusions in ferrosilicon with slag particles containing MgO3, when ferrosilicon was added and mixed at the end of refining period.(2) Increasing rate of Al203 content in molten steel was lowered by the use of low aluminium ferrosilicon, as compared with the use of commercial grade ferrosilicon. It resulted in decrease of Al2O3 content in the molten steel before tapping and in the ingot bottom. However, microscopic structure and mineral composition of oxide inclusions in steel were same as in the case of the use of commercial grade ferrosilicon.(3) It was noted that macroscopic inclusions were greatly affected by Al content in ferrosilicon.

均熱中の合金と合成酸化物との反応

In order to obtain informations on the change of oxide inclusions in steels by annealing at high temperatures, synthetic oxide slags were embeded into various alloys. After annealing at high temperature, the size and shape of precipitates were observed microscopically and changes of both compositions were analysed by EPMA. Results obtained here are as follows:(1) Oxide particles precipitated in a layer around the embeded oxide. The thickness of the precipitation layer broadened with increases of time, temperature and FeO content in oxide, and shortened with decrease of initial concentration of alloying element in the alloy.(2) The precipitates had various shapes including sphere, and the size increased with time and temperature. FeO content in precipitates decreased as the precipitate departed from the oxide/alloy interface, and concentration of alloying element in the alloy near the precipitates became far lower than the initial concentration.(3) FeO content in the embeded oxide decreased. Besides, it was observed that silicon transfered from the oxide into alloy.

鋼中MnO-SiO<SUB>2</SUB>-Al<SUB>2</SUB>O<SUB>3</SUB>系介在物の熱間圧延過程における挙動と鋼の引張り強さなどにおよぼす影響

The oxide inclusions in commercial steels consist mainly of the simple orthe complex oxides formed from the system MnO-SiO2-Al2O3.In the present investigations, the behavior of those oxide inclusions in steels during hot-rolling was observed by the same procedures as used for our previous work: that is, the steel specimens containing uniformly a certain amount of those oxide inclusions were prepared by powder metallurgy technique. These steel specimens were hot-rolled under the following conditions: the rolling temperatures were 1250-1000°C and 1000-800°C, the rolling ratio was 1/5. Then, changes of inclusions in shape, composition and crystallographic structure during hot-rolling were examined. The tensile tests of rolled steel specimens in the rolling direction were carried out to examine the influence of those inclusions on tensile strength of the steels.The main results were as follows:(I) The complex inclusions having nearly the same melting or softening points as the rolling temperature, were deformed plastically and turned into the stringer type. When both the rolling temperature and ratio are maintained to constant, the lower the melting point of inclusion and the better the homogeneity in composition of inclusion are, the larger the degree of deformation of inclusion becomes.(2) The complex inclusions formed from the system MnO-SiO2, having low melting points were softened at 1000°C.(3) When the steel specimens coexisting MnO and SiO2 of simple oxide inclusions were rolled between 1250°C and 1000°C, both inclusions were consolidated, tusned into manganese silicates whose melting points were lower, and deformed plastically. Those manganese silicates were partly crystallized into tephroite (2MnO.SiO2).(4) Those oxide inclusions in steels affected scarecely tensile strength of steels.

鋼中酸化物 (主として複合酸化物) 系非金属介在物の電解抽出法について

In the study of non-metallic inclusions in steel, the methods of extracting them are recognized one of the important techniques of study. In the series of our investigation on the behavior of oxide inclusions in steel in hot-rolling process, we adopted the electrolytic extraction method using Koch-Sundermann (type) cells and with neutral sodium citrate solution as electrolyte. This is one of the methods by which it is possible to extract stably and reliably the oxide inclusions from steel. But, in our investigation, we thought that it was necessary to examine the adaptability of the electrolytic method in regard to extracting such inclusions as α-Al2O3, TiO2, SiO2, MnO2, FeO, (Mn, Fe) O, FeO·Al2O3, 2FeaTiO2, 2FeO-ESiO2, MnO-ESiO2 and 2MnO-ESiO2.Therefore, the steel specimens containing uniformly a certain amount of particular oxide inclusions were prepared by means of powder metallurgy, and these specimens were dissolvedanodically at definite conditions. The extracted inclusions were examined by weighing and chemical as well as X-ray analysis, and the degree of extraction of the different inclusions were observed quantitatively.The results were as follows:(1)α Al2O3, TiO2, SiO2 and FeO could be extracted almost to the full, but MnO could scarcely be extracted.(2) As for (Mn, Fe) O, oxides rich in MnO could not be extracted at all. What was extracted had changed their composition because MnO in (Mn, Fe) O dissolved selectively during the electrolytic extraction.(3) FeO·Al2O3 and 2FeO·TiO2 could be extracted perfectly. The extraction percentages of 2FeO·SiO2, MnO·SiO2 and 2MnO·SiO2 were between 60 and 80%, but these extracted inclusions had not changed in quality.

固体鉄と共存するMnO, SiO<SUB>2</SUB>およびCr<SUB>2</SUB>O<SUB>3</SUB>の還元性雰囲気加熱における挙動

In the previous studies concerning the behavior of oxide inclusions in steels in the hot-rolling process, the steel specimens were made by the method of powder matallurgy: that is, the iron powder was mixed uniformly with a certain amount of synthetic oxide inclusions, shaped by pressing, and sintered in H2 atmosphere. It was found that a part of mixed oxide inclusions disappeared by reduction.This phenomenon suggested that a part of the synthetic oxide inclusions was reduced by H2, and the metallic elements produced by the reduction were then dissolved in solid iron. Consequently, the activity of those elements was lowered, and the reducibility of oxides increased considerably.The present investigation was carried out in order to make the behavior of oxides in steels clearer and know more about the reduction. The specimens made of the iron powder containing a certainamount of MnO, SiO2 or Cr2O3 respectively were held at the constant temperature of 800°C to 1100°C and in the H2-H2O gas under the constant PH2O/PH2, ratio. When the equilibrium state was attained, the change of weight of these specimens due to the reduction of oxides was measured by thermo-balance, and the reducibility of the oxides at each temperature was investigated.Furthermore, the activity and the activity coefficient of the Mn, Si and Cr elements in solid Fe-basealloys were calculated by combining the experimental value of Mn, Si and Cr concentrations and the thermochemical data concerning the reduction of the oxides.

鋼中酸化物系介在物の熱間圧延中における挙動

鋼中酸化物系介在物の熱間圧延中における挙動

Beitrag zur Lösungsspektralanalyse von Oxydeinschlüssen in Stahl

Abstract A solution microtechnique for the spectrochemical analysis of oxide inclusions in steels is described. A sample of about 100–500 μg is fused with a flux mixture of sodium carbonate-potassium carbonate-borax, the melt dissolved in a hydrochloric acid solution of cobalt nitrate (internal standard) and citric acid, and the solution made up to known volume by means of a pipette. An aliquot of 20 μl is put on a preheated graphite electrode and a high voltage spark discharge is used. SiO 2 , Al 2 O 3 , FeO, MnO, Cr 2 O 3 , CaO, MgO and CuO are determined with a deviation from the mean of ±5·5 per cent. The time required for complete analysis is about 55 min.

Some applications of X-ray analysis methods to steelworks' problems

The paper summarizes a number of X-ray investigations carried out in a steelworks' research laboratory. In the first part, the examination of silica, magnesia and fireclay refractories is described and it is shown that X-ray data on the raw material and fired products may be of considerable value in determining the suitability of certain minerals for use as refractories. In addition, the changes in constitution and crystalline texture during service are discussed. The second part deals with metallurgical problems associated with chromium magnet and silicon transformer steels and oxide inclusions in steels. A large part of the information has already been published.