Abstract: Recentl man metallurgists heve been working with steel refining by using maganesium as deoxidizer and desflfurizer which also leads to better morphology of nonmetallic inclusions. That it might be very difficult to add maganesium in was the reason for the previous works to fail. The trouble is that the partial pressure of maganesium is very high at the melting temperatures and at the same time its solubility in the liquid steel is rather small. In this article, the effect of injecting Mg-powder on deoxidation and desulfurization by using Ar-gas as carrier based on thermcdynamic data stove in Aachen university and the effects of the pressure and flow of Ar-gas on the technology mentioned above have been calculated. The effective injecting technology was determined experimeutally and the appropriate controlling parameters were chosen. Maganesium can be successfully insected into the liquid steel at 0.1~0.3NL/min of Ar-gas flow under 1-3 atm. The oxygen content was decreased to 4ppm in the liquid steel to be refined. The sulfur content 10ppm. The graduation of oxides and sulfides was 0-grade. This sizes are less than 5μm. Mg-oxides and sulfides in the inclusions were increased with the increase of amount of injecting maganesium. However the total amount of inclusions were decreased and the shape appears as sphere. The inclusions remain unchanged shape during hot deformation. The anisotropic characteristic which usually exists in materials disappeared completely especially the notch-impact toughness at the transverse direction was increased by 2-3 times. The impact toughness at the different temperatures the transition temperatures and the inclusion shapes on the fractures for the materials to be refine 1 were also discussed.
Abstract: When Thin foil Specimens of Copper-iron alloys Containing metastable fcc r-iron are bombarded with argon ions the precipitates are induced to transform martensitically to bcc iron. Using stereo microscopy technigues it was established that (1) transformation is limited to those particles near the Surfaces of the Specimen, (2) Particles on the non-irradiated Surface Can transform even when the irradiation damage does not extend so far. The transformation is therefore thought to be initiated by elastic Surface (Rayleigh) waves Set up by the ion impacts. High resolution lattice fringe electron microscopy of bombarded Specimens Showed that both partially transformed and fully transformed Precipitates exist. The fully transformed precipitates have the twin structure already Seen with Conventiond TEM, but the partially transformed precipitates Contain Very thin laths or plates of martensite Parallel to the Close-packed planes of the untransformed fcc regions. Complete transformation is thought to be associated with partides that have a substantial amount of free Surface, while Partial transformation is probably Characteristic of particles that are fully constrained by the copper matrix.
Abstract: Borided layers on the surface of Armco iron and eutectoid carbon Steel were eutectified in furnace and then scanned continuously with laser beam of high power densities. The laser melted metal were cooled and then solidified with extra-ordinary speeds by the heat extraction action of the cold substrale. It was found that the eutectic structures are composed of α-Fe+Fe2B phases in the Fe-B alloy layer and of α-Fe + Fe3(C, B) phases in the Fe-C-B layer. Fe2B is in the square rod-shaped form and Fe3(C, B) in the lamellar form respectively after furnace treatment. The phase constitution and the morphologies are not altered, but the inter-rod and interlamellar spacings are reduced by 40 and 100 times respectively after the laser melt quenching. The hardness of eutectic structures are thus greatly enhanced and the hardness-dimension relationship for each alloy system obeys the Hall-Petch equation.
Abstract: Af the base of steady state creep rate eguation for multicompment particle-strengthened alloys and in condideration of the stacking fault energie and resisting stress theory in creep, a new generalized steady-state creep rate equation is proposed: $\mathop {\rm{\varepsilon }}\limits^{\rm{\cdot}} {\rm{s}}={\rm{A}}''{(rs)^{{\rm{no}}}}{[\frac{{\sigma -{\sigma _{\rm{p}}}}}{{{\rm{E}}({\rm{T}})}}]^{{\rm{no}}}}\exp (-\frac{{\rm{Q}}}{{{\rm{RT}}}})$ The applicability of this equation is assessed by the creep of Ni-Co binary alloys, several γ' or oxide dispersion strengthened nickel-base superalloys, low γ' fraction strengthened nickel-base superalloys (Waspaloy) with different contents of cobalt and high fraction γ' strengthened nickel-base superalloys (Udimet‰) with different contents of cobalt. The result of this assessment is available.
Abstract: A new type worm drive with part of toroid surface of ring with circular cross section is dealt with this paper. A set of formula of twice enveloping has been derived. The contact lines. The first and second kind boundary lines. The reclative normal curvature. The angles between the contact lines, relative velocity vetors and tooth axical profiles in various parameter conditions have been calculated by means of computers. The systemalic analysis of that mentioned above is given. We concluded that this new type of worm gears with small ratio has much merit than that with big ratio. After primary analysis of the different parameters. We have pointed the practical value and application ranges of this worm gears. moreover, the simplization and generalization in calculate have been paid more attention to.
Abstract: For ultra-high strength steel and aluminum alloy, a fatigue crack could initiate from a notch tip under a cyclic compressive load. The th-resholp value Δσth or ΔKth(ρ) for fatigue crack initiation under a compressive load was four times as high as that under tensile load. The crack grew at a decreasing rate until eventually it stopped growing under cyclic compressive load and the maximal length of the fatigue crack was only 0.2-0.5mm. The crack nucleation under comdressive stress became easier and the propagation distance of the fatigue crack was longer if the mimimum cyclic compressive load was near zero.
Abstract: The rolling theory deals with only simple rolling condition, but in fact, any rolling procees has, more or lees, some nonsymmetry For instance the diameters between two worle rolls are not absolutely equal This papes diecribes the experience on a four-high strip mill The tests proved that even a little difference between two xork rolls in diameters may cause unequal distribution of the rolling torque. This ought to be the foundation of strength computation of driving pavts. Under certain conditions, cold strip mill may use "single-roll drive and unequal diameter rolling" The practice proved that it could bring us three advantages:increase in reduction, decrease of the rolling pass and the saefty of driving parts.
Abstract: This paper describes the results of the theoretical analysis and experiments about the inklueuce of the difference df the roll diam eter on the rolling parameters They incuade the ralative slip Between roll and strip the rolling load the rolling torque and the quality of product etc.
Abstract: Deformation of steel ingot with liquid core during rolling belongs to deformation of two-phase (solid and liquid)is a new domain of plastic deformation. At present, few information is available at home and abroad. We have very seldom seen theoretical analysis especially. This paper deal mainly with deformation law of steel ingot with liquid core, such as uneven spread produced under the same drafting schedule; longitudinal uneven gauge produced after rolling; total elongation and fish-tail change with liquid core rate of steel ingot; join mark and splits etc. produced surface of the rolled metal.
Abstract: Using Visioplasticity method,the flow and deformation of rolling process have been studied.The main conclusions are as follows: 1. Visioplasticity method is usefal for analyzing flow and deformation of metals during rolling. 2. The deformation and flow of metal are not homogeneous. 3. Correct results can be obtained if there is suitable method to determine the flow lines.
Abstract: This paper reviews the "Metallurgical criterion" of slab solidification during continuous casting. The effect of the following variables on metallurgical criterion of slab, solidificafion has been studied using a methematical model of heat transfer:casting speed, spray water intensity, water distribution in spray zone, superheat in tundish, convection in the liquid pool and spray water Temperature. The authors has prepared a nomogram considering fhese factors in which reasonnaable technology parameters are executed.
Abstract: This paper presnts the influence exerted upon the quality of carbon slab by EMS. The experimental results abtaned are as foll 1. Evident effects of EMS on the solidified structure of slab have been bserved which is beneficial to the formation of equiaxed crystal under the condition of this experiment. The ratio equiaxed crystal in whole solidifieds ystem reaches its highest value when value of stirring intensity paramater I $\sqrt {\rm{f}} $ is 1500. 2. Depending upon the stirring intensity highest flow rate of liquid steel Can be as high as 35 cm/sec 3. EMS was exercised af the position which was 4.6 m below the meniscus of the mould. The stirring range was about 4.0 m along the casting drection. The upper area was 2.0 to 2.6 m and the lower area was 4.6 to 6.0 m from the meniscus of the mould. 4. when one-direction stir was adopted, the flow rates and flow direction of the liquid steelat the two sides along the wide direction of slab was different, as a result, the solidification structure was not symmeTrical and the "white bands" might appear. 5. under the condition of this experiment, the distribution of in clusins at the inner eure side of the casted slab has two peak values.
Abstract: There are three.nining stopes in Fu-shan Iron Mine. Based on th eir ore-tonnage, Ore-grade, sulphur content and silica content cond iti ons, reasonable blending of raw ores has to be carried out in order to make the commercial ore fulfilling the grade index requirqement and obtaining the optimizing profit index. In this paper linear programming simplex method is used to solev the ore blending system giving the mathematical model for the Fu-shan iron ore blending problem and its corresponding simplex method chard This is carried out in the M-150 compater using FORTRAN program. From the computing result we obtian the optimizing ore-blending system analysis of the influential factors of promoting profit index poin ting out the suitable ore-blending system used in Fu-shan Mine practi on and suggesting the opinion of further promoting the economical benefit.
Abstract: Me have investigated of health status on 622 staff and workers with 50 years of age and above of Beijing Unirersity of iron and steel Technology. In this group 87.3% were below 60 years of age. Major diseases encountered were cardiovascular diseases, such as hypertension (30.9%),coronary heart disease (4.5%) and myo-cardial Ischemia (5.1%), borderline hypertension (14.8%),cerebral vascular disease (1.4%),aortic sclerosis (10.3%), hyperch olestero 1emia (27.3), hypo-HDL-cholesterolemia (16.4%),anemia (30.9%), malignancy (0.6%), chronic bronch it is(18%),and chronic m (9.3%) etc. Among this age group, some diseases were discoverd by us,they had seldom complained of signs of discomfort. This suggested that health care must be paid not only to the elderly,but also to the preaging members.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
