Large Steel Castings Research Articles

Efficiency of using heat-insulating mixtures to reduce defects of critical parts

A study was conducted to reduce defects in especially critical cast large-sized parts of freight car bogies. The side frame was used as the part under study. The main factors influencing the formation of hot cracks in large steel castings are presented. To avoid the rejection of steel castings, the use of heat-insulating mixtures to reduce hot cracks has been investigated. The temperature distribution of the melt along the height of the ladle is modeled. An analysis of the influence of the order of pouring molds and pouring temperature on the number of hot cracks in the side frames is presented.

Important Key Process Simulations in the Field of Steel Metallurgy

During the last decade, the chair for ‘Simulation and Modelling of Metallurgical Processes’ (SMMP) has worked on different metallurgical processes with the highlights of the following five industrial relevant topics: (i) modelling the as-cast structures of large steel castings; (ii) exploring the formation mechanisms of macrosegregation; (iii) describing magnetohydrodynamic and electrochemical phenomena in remelting processes, (iv) understanding how solidification and flow can be influenced by magnetohydrodynamics during steel continuous casting; and (v) describing nozzle clogging in steelmaking processes. In this contribution, the main achievements from the group on the above five topics are briefly described.

Research and Improvement of Welding Repair Technology for Large Steel Castings of Marine Diesel Engine Based on CAD Software

CAD (Computer Aided Drafting) is the Massachusetts Institute of Technology in the United States to propose interactive graphics research program. Marine cast steel parts generally have features such as large cross-section dimensions, complex shapes, and hard to repair once damaged. In this context, this article takes the basic introduction to CAD software as the starting point, focuses on the common cracks and causes of welding cracks in the welding of large steel castings, and takes the repair of diesel engine cylinders as an example to analyze steel castings. Common welding repair methods. This paper analyzes the cracks and causes of weld cracks commonly found in the welding of large steel castings, and take the repair of diesel cylinders as an example, analyzed the common welding repair methods for steel castings. The welding repair through the cylinder shows that under the strict control of the welding process, the heterogeneous cold welding repair process is practically applicable to the on-site repair. And cracks may occur in the nickel-based welds after the diesel engine actually operates. The welding repair process should be strictly controlled and appropriate measures should be taken to eliminate the welding residual stress.

Thermal Conductivity of Selected Ceramic Materials at a Transient Heat Flow

In this paper, we present comparative investigations. We examined two kinds of ceramic materials used to produce bricks for isothermal cleading of the riser heads of middle and large steel castings. The ceramic materials were characterised by a low specific density (No. 1 − ρ = 0.854 g/cm3; No. 2 − ρ = 0.712 g/cm3). Thermal conductivity tests at a transient heat flow were performed by analysing the heating process of samples taken from the tested ceramic bricks, placed in a special mould in which metal was poured, and by recording the cooling process of the casting. The method proposed in this paper for the determination of samples’ thermo-physical properties is based on measuring the temperature field of the casting–sample system by means of thermocouples situated in various measuring points; it allows the direct investigation of cooling and solidification processes of metals in sand moulds. The heating process of the ceramic samples was analysed by measuring the temperature in five points situated at various distances from the heating surface (casting–sample surface). A large difference in the heating rates of samples of different materials was revealed in our comparative investigations, which indirectly indicated the materials’ heat abstraction ability from the casting surface. The ceramic material characterised by a lower density much slowly conducted heat and, therefore, appeared to be a better material for insulation cleading. At the depth of 40.0 mm, we measured differences in the heating degree corresponding to more than 190 °C. The aim of this comparative study was the evaluation of the suitability of porous insulating materials as cleading of riser heads used in the production of large steel castings.

Correlation of microstructure and mechanical properties of Al2O3‐C bodies containing Nano‐Al2O3 and Nano‐TiO2 additives

AbstractAl2O3‐C foam filters have been successfully used for steel and aluminum melts filtration. Improving the high‐temperature mechanical properties enhances the capability and application of these filters for the filtration of large steel casting parts along with ingot casting or continuous casting of steel for long periods of time. In this study, adding nano‐Al2O3 and/or nano‐TiO2 to the composition of Al2O3‐C filters was investigated. Uniaxially pressed Al2O3‐C samples containing additives in the range from 0 to 1.0 wt% of nano‐oxides were prepared. The physical and mechanical properties, as well as microstructural analysis, were measured after sintering at 1600°C for 5 hours under a petroleum coke bed. The results showed that the presence of nano‐Al2O3 particles in the composition led to an increase in the cold crushing strength (CCS) due to the formation of the Al3CON phase which acts as a chemical bonding between Al2O3 particles and the carbonaceous matrix. On the other hand, the addition of 1.0 wt% of nano‐TiO2 in the composition caused an increase of 50% in the hot modulus of rupture (HMOR), attributed to the formation of columnar Al2O3 grains in the microstructure.

Industrial tests of heat-insulating material based on graphite intercalation compounds

The results of industrial tests on using graphite intercalation compounds for heat insulation of large steel casting risers were considered in the paper. The basic material for casting products was steel 30L. Two methods of using graphite intercalation compounds for riser heat insulation were proposed. The first method was to apply graphite intercalation compounds (GICs) to completely filled risers, and the second one was to apply GICs to risers, partially filled with molten metal. The studies have shown that the temperature of the metal mirror surface of the completely filled riser is close to the metal crystallization temperature, and in this case using GICs does not prevent the formation of skin on the metal surface, leading to the formation of shrink hole. Using GICs in partial filling of risers with molten metal leads to the fact that applying GICs to the metal mirror prevents the skin formation on metal surfaces, as metal has a temperature higher than the crystallization temperature. The conducted industrial tests have shown that the proper use of GICs for large casting resins allows reducing the metal consumption by 5–8 % of the casting weight.

Control Volume Simulation of Casting Directional Solidification

Quality demands of castings is elemental in recent years and becoming more stringent. Foundries are faced by the need to produce high quality castings, but nonetheless to produce them economically. To fulfill this demand, experimental castings, especially in case of individual production or small runs, are uneconomical. In these cases computer simulation can be the only economical tool for testing and approval. The modulus technique of Chvorinov is an applicable method to examine the local solidification process and to determine the application of chills, geometry modification and feeding. Numerically the control volume method is used to check the solidification process of large steel castings with non-uniform wall thicknesses.

Modelling and simulation of A segregates in steel castings using thermal criterion function Part I – Background and validation

The present paper is the first out of two papers in which thermal criteria for modelling and optimising, i.e. minimising, the formation of A segregates are investigated. One specific thermal criterion has been incorporated into a transient three-dimensional thermal fluid model inside a commercial simulation software package. It is then used for predicting A segregates inside a large steel casting, i.e. a forging ram. In part I, experimental data obtained from a foundry serve to validate the given criterion and to evaluate the critical value for A segregate initiation for one alloy composition on the forging ram. In part II, the criterion forms the basis of shape optimisation of the original casting layout for the ram. More specifically, unknown optimal shapes and sizes of the top riser and chills are sought by means of autonomous optimisation to establish a better solidification pattern, which would eliminate the likelihood of centreline porosity and A segregates.

Establishment of Quality Technology for Large Steel Castings

Establishment of Quality Technology for Large Steel Castings

Solidification Analysis of Large Steel Castings

Solidification Analysis of Large Steel Castings

Antipickup and easy knock-out core sand mixtures for producing large steel castings

Antipickup and easy knock-out core sand mixtures for producing large steel castings

Predicting Shrinkage in Large Steel Castings

Predicting Shrinkage in Large Steel Castings

大形鋳鋼品の製造技術の現状と問題点について

大形鋳鋼品の製造技術の現状と問題点について

X-Ray Stress Measurement of Large Steel Casting

The residual stress in a large steel casting (1000×1000×400mm) was measured by means of the photographic X-ray method developed in our laboratory. Since the grain size of the steel casting is large, the obtained diffraction lines on the films were spotty and the spots scattered in the radial direction. The peak positions of the diffraction lines was determined by averaging the distance between each diffracted spot and line of the standard substance arithmetically.The mean value of the residual stress for the specimen annealed at 940°C for 16 hours was 7.6kg/mm2 in tension on the surface of the feeder head side and 10.5kg/mm2 in tension on the surface of the bottom side. The specimen was then cut 15mm in depth from the surface of the feeder head side. The mean residual stress on the newly appeared surface was 3.2kg/mm2 in compression and it was 7.1kg/mm2 in tension on the opposite side. When the specimen was annealed at 650°C for 8 hours, the residual stresses on both surface became almost zero. The distribution of the residual stress in the sample were discussed.

The Metal Penetration of Self-Hardening Molding Sands for Large Steel Castings

The Metal Penetration of Self-Hardening Molding Sands for Large Steel Castings

Ultrasonic inspection of large steel castings: Greenberg, H.D. Foundry, Vol 96, No 3 (March 1968) pp 68–73

Ultrasonic inspection of large steel castings: Greenberg, H.D. Foundry, Vol 96, No 3 (March 1968) pp 68–73

大型鋳鋼の靱性と質量効果

Ductility and mass effect in large steel castings were studied on production scale, using experimental castings of Al killed steel and 0.36%C steel of which dimensions are 200×200×650mm, 300∅×650mm, 600×650mm∅, 1000∅×1050mm and 80×140×180mm respectively under both conditions of single normalizing and double normalizing.The results obtained are summarized as follows:1) Fine austenitic grains were obtained by double normalizing, compared with single normalizing, in both high Al-contained cast steel and low Al-contained cast steel. Coarsening temperature can considered to be 1050°C for high Al-contained cast steel and 1000°C for low Al-contained cast steel.2) Mixed grain obtained in the low temperature range in single normalizing is thought to be primary mixed grain influenced by the initial grain at the as-cast state, and that in the higher temperature range is secondary mixed grain caused by mixture of coarse grain and incompletely grown grain. Primary mixed grain in double normalizing is seemed to be caused by great difference between coarse grain of prior mixed grain and new grain formed by subsequent treatment.3) Ductility of steel castings is generally more significantly improved by double normalizing than by single normalizing, but injured by mixed grains that appear in the begining of coarsening.4) Concerning to ductility of sound and segregating zone in large steel castings, low temperature of 1000°C-1050°C is effective for diffusion annealing of sound zone, and high temperature of 1100°C forsegregating zone. Consequently, in accordance with ductility level demanded for cast steel, it is industrially necessary to select optimum conditions of diffusion annealing; diffusion annealing should be carried out in the low temperature range when ductility of sound zone is not enough high, but in the high temperature range when ductility of segregating zone is important.5) Mass effect generated on casting in large steel castings is greatly influenced by C content in this experimental casting alloyed with small amount of Ni and Cr.6) As for mass effect generated on heat treatment, ductility of 300mm dia casting hardly decreases in even the inside, but it decreases abruptly for inside castings of 600, 1000mm dia.If factor of mass effect is considered, it is also possible for steel castings to estimate tensile strength nondestructively from chemical compositions and heat treated conditions.

Production of large steel castings

Production of large steel castings

Study on the Solidification Process of Large Steel Castings

Study on the Solidification Process of Large Steel Castings

Production of large steel castings

Production of large steel castings