Synthetic Chromite was prepared and reduction studies were carried out with different amounts of carbon in the mixture in the temperature range 1150-1300°C. Partially reduced material was analysed by X-ray diffractometry which indicated the presence of Fe, Cr2O3, unreduced chromite, Cr3O4 and residual graphite. An analysis of the results on the basis of quasi steady state equation for diffusion control through product layer, phase boundary reaction and unsteady state diffusion of oxygen, reveal, that the process can best be described by diffusion control of oxygen towards the surface of individual particles with fast reaction at the surface. Activation energies for this diffusion process was estimated to be about 57kcal/mol. This does not change with the carbon content in the initial reduction stage (upto 25%), investigated in this work.

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By melt-quenching technique, nonequilibrium austenitic alloys possessing high strength and hardness combined with good ductility have been found in Fe-C-Mo and Fe-C-W ternary systems. This formation region is limited to about 1.0 to 2.4wt% C and 3 to 22wt% Mo for Fe-C-Mo system and 1.0 to 2.4wt% C and 3 to 24wt% W for Fe-C-W system. The austenite phase has ultra-fine grains of about 0.2μm in diameter. Their Vickers hardness and tensile strength increase with increase in the amounts of carbon and molybdenum or tungsten, and the maximum values attain about 710 DPN and 1 450MPa for Fe-C-Mo system and about 700 DPN and 1 500MPa for Fe-C-W system, respectively. Elongation increases with decreasing carbon and molybdenum or tungsten contents and reaches about 2% for Fe-1.4%C-9%Mo and Fe-1.4%C-15%W. The relatively large elongation at low concentrations of carbon and molybdenum or tungsten results from the transformation-induced plasticity of austenite to martensite. In addition, the changes in microstructure and mechanical properties of the tempered austenitic alloys have been investigated and it has been observed that a large secondary hardening occurs in a wide range of about 600 to 900K for Fe-C-Mo alloys and 500 to 900K for Fe-C-W alloys. The hardening is due to bainitic transformation from austenite to ferrite and M₃C in the temperature range from 500 to 700K and due to phase transformation from austenite to martensite and carbide in the range from 700 to 900K. Thus the present alloys may be attractive as fine gauge high-strength materials.

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With a view mainly to safety considerations of LPG storage tanks, V-notch Charpy, three point bending COD and wide plate tension tests were undertaken on four plate materials and thirteen weld metals welded by shielded metal arc, submerged arc and automatic TIG welding processes. In respect of fracture toughness of the weld metals, some correlation was seen between V-notch Charpy absorbed energy and three point bending COD value, both these values being found to be particularly high for Ni free 1.4Mn-Ti-B type weld metal. For the base metal, Ti-added Al-killed steel showed good toughness in the heat-affected zone by both V-notch Charpy and through-thickness notched three point bending COD tests. This latter test applied to specimens with surface notch, however, yielded a low COD value within 400μm of fusion line for all the metals tested and for all values of heat input. Nonetheless, tensile tests using wide plate welded specimens with artificial defects located in the region of lowest toughness proved that, from considerations of fracture mechanics, all the joints possessed ample strength against brittle fracture initiation. It should thus appear that evaluation of welded joints may not always be valid when based on local three-point bending COD test, and that it should be more practical to assess the safety of such welded joints by wide-plate tests.

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The purpose of this work is to present a stationary method for measuring heat transfer characteristics between a hot solid surface and impinged droplets. The stationary temperature distribution of the thin metal disk by impingement of a steady stream of uniform water droplets onto its central zone was measured. The results were analyzed to determine the heat transfer coefficient of spray cooling. It was found that the wetting regime was prevailing below 350°C and the non-wetting regime was above 400°C of the metal surface temperature. Within a few drops per second, the heat transfer coefficient is independent of collision rate of droplets to the surface in the non-wetting regime, while it is dependent even on such a small rate of droplets in the wetting regime.

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Behaviour of specimens arranged of steel sheets of various thickness into a V Gharpy sample under conditions of dynamic bending has been investigated. The theoretical analysis into the dependence of the sheet thickness B₁ on the “crack driving force” G_c shows that the function G_c(B₁) can be split into four zones characterized by different course of fracture. In the first zone ductile cleavage accurs and the G_c(B₁) relation is linear. The second zone is characterized by origination of complex configuration of the fracture surfaces of comparable thickness, which results to fractures well-demanding from the view point of energy. In the third zone the mixed fracture originates. That part of curve G_c(B₁) is originating in principle by the transient curves G_c (t) of specimens of a greater thickness. The fourth zone is characterized by occurrence of brittle fractures only.
From the experimental part of the work it follows, that the results acquired with the structural weldable steels are in reasonable conformity with the following equation Z•B^k5₁=k₆ where, Z=KCV_max-KCV_min/R_pdynB₁|tp|/t is a dimensionless parameter describing behaviour of specimens at the transition from a cleavage to ductile fracture.

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Temper embrittlement and hydrogen embrittlement have been studied through systematic changes in composition of HY 130 steel using Charpy V-notch impact specimens and modified wedge-opening loaded specimens aged at 480°C for 0 to 1 000h. The results have shown that the threshold stress intensity for hydrogen-induced cracking decreases and the fracture appearance transition temperature increases as the impurity concentration increases at the grain boundaries with ageing time, and that an addition of 0.30% Al and an elimination of Si, Mn, N and P in the HY 130 steel results in almost complete resistance to temper embrittlement and to hydrogen embrittlement.

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As a series of study to develop a procedure to make a quantitative evaluation of corrosion data, it is demonstrated that the extreme value statistical analysis can be successfully applied to various localized corrosion data acquired from machine components presently in service, and that corrosion life prediction can be done by examining the time dependence of predicted maximum depth of penetration.
The following localized corrosion data are obtained from the machine components in service: tuberculation of carbon steel feed water pipes for hydroelectric power stations, pitting and crevice corrosion of cupro-nickel heat exchanger tubes employed for a chilling machine using a reclaimed water as a coolant, and crevice corrosion of type 316 stainless steel swathed joints used for high speed liquid chromatography are analyzed thoroughly.

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Studies have been made on the rates of dissolution of stationary or rotated cylindrical iron specimens containing various amounts of oxygen into molten carbon-saturated iron alloys. The explored temperature range was from 1200°C to 1 450°C. The highest oxygen concentration of the specimen was 1.14%. The dissolution rate was determined from the rate of decrease in diameter of the cylinder.
In the case of stationary dissolution, oxygen in the iron specimen, that is, the evolution of CO was found to have a marked effect on the dissolution rate. This phenomenon is shown to be analogous to the mass transfer at a gas evolving electrode. At high oxygen contents of the specimen, a phenomenon analogous to nucleate-film boiling of liquid over a hot solid surface was observed. The highest dissolution rate which was observed at 1 400°C for iron containing 0.96% oxygen is 590 times as large as the lowest rate observed at 1200°C for aluminum-killed iron.
In the case of rotational dissolution of iron specimens containing oxygen, at lower rpm the rate is controlled mainly by the extent of CO evolution. At higher rpm, the effect of rotation becomes predominant.

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This paper is concerned with the new development of an electrode-type mold level sensor and a mold level control system with this sensor for continuous casting machines. The principle is based on the electrical conduction of powder floating on molten steel.
The resistance between the mold powder and molten metal, which is proportional to the distance between the electrode and metal surface, is measured by the electrode inserted in the mold powder. A servo-device allows the electrode smoothly to follow the movement of the free surface of the molten steel. The mold level control system using this level sensor was analyzed by a simulation model. It was confirmed that the level sensor was able to accurately detect the movement of level for actual operation.
The performance of the electrode-type level sensor is as follows: 1) measurement range: 500mm, 2) maximum follow-up control speed: 70mm/s, and 3) response time: 1s.
It has been confirmed that the electrode-type level sensor makes possible the control of the molten steel level within±3.5mm, even when electrode-magnetic stirring is applied.

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Research and Development personnel spend a considerable portion of their time in investigating, collecting, classifying and filing information that comes in their way. In fact, the portion amounts to such a magnitude that a good supporting system is desired for processing information efficiently so that they can devote more time to their essential R & D activities.
This paper discusses how an information management system in an enterprise should be, describing mainly activities at Technical Information Section of which the author is in charge. In this paper, information is divided into in-house information and outside information. For the former the basic concept is to prohibit individual staff members from hoarding information and manage it as an asset of the entire staff; for the latter, emphasis is laid on making an efficient use of information services offered by outside organizations which have recently improved rapidly.

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In order to develop new high manganese non-magnetic steels that can be employed to extensive applications ranging from cryogenic to elevated temperature uses, the effects of C and Mn on their magnetic permeability, thermal expansion coefficient and mechanical properties are investigated.
It is found that the relation between thermal expansion coefficient, β, and both C and Mn contents can be expressed by the following linear regression equation: β(×10^-6/°C)=17.66+3.82C(%)-0.22Mn(%). Good mechanical properties are exhibited in the wide range of Mn contents between 18% and 30% at room temperature, while there is a tendency that this optimum range of Mn content is narrowed at cryogenic temperature.
Then, H-shapes, round bars and deformed bars are manufactured at the workshops using 5t vacuum melted ingots, aiming to establish the conditions for practical processes for final products and to study such various characteristics of the products as their physical and mechanical properties, machinability and weldability. As a result, it is shown that all of those products have excellent properties as non-magnetic steels.
In addition, the manufacturing of non-magnetic pinch rolls attached to the electro-magnetic stirring equipment on the continuous casting machine is described in detail as one of the practical applications of the high Mn non-magnetic steels.

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