Conventional Ingot Casting Research Articles

Fe-Ni 인바(Invar) 합금 박판의 가공성 향상을 위한 방향성 조직 제어

42Ni-Fe Invar alloy strips were fabricated using conventional ingot casting and melt drag casting followed by rolling. Mechanical properties such as tensile strength, elongation and blanking deformability of the strips were evaluated. The properties were strongly depended on fabrication methods. Tensile strength and elongation of all strips were in the range of <TEX>$40-60kg/mm^{2}$</TEX> and 26-35%, respectively, which are enough values for the manufacture of the final products. In some of the strips, however, burrs occurred at deformed surface. The properties of strips were explained in terms of microstructure such as grain size and texture formation during rolling. Additionally, strips by melt drag casting method were compared to those by conventional ingot casting.

Effect of Mg content and solution treatment on the microstructure of Al-Si-Cu-Mg alloys

Three different quaternary alloys Al-6Si-3Cu-xMg (x = 0.59, 3.80 and 6.78 wt.%) were produced using conventional ingot casting metallurgy. The study was focused to investigate the effect of magnesium and solution heat treatment on the microstructure. Results shown variations in composition and morphology for the silicon-rich phases as well as a change of the predominant copper-rich phase Al2Cu (θ) to Al5Cu2Mg8Si6 (Q phase) when magnesium content is increased. The amount of Mg in solid solution was constant for the three different cast-alloys, increasing considerably after solution heat treatment to 2.7 at.% for the alloy with higher Mg content This fact allowed to obtain Cu:Mg ratios (in at.%) in solid solution lower than 1.0 for the alloys with 3.80 and 6.78 Mg wt.%, impossible to reach for the alloy with low Mg content. During dissolution process, Al2Cu phase was observed to be more suitable to dissolve than Q phase. Fragmentation, spheroidization and coarsening of Q and silicon-rich phases were observed. Solution time required for these processes occurrence was longer for Q phase. Solution heat treatments at 480°C for 12 h were found to be appropriate for the studied alloys.

Properties of cold-work tool steel X155CrVMo12-1 produced via spray forming and conventional ingot casting

Properties of cold-work tool steel X155CrVMo12-1 produced via spray forming and conventional ingot casting

Effects of microstructural evolution on superplastic deformation characteristics of a rapidly solidified Al-Li alloy

This study is concerned with the effects of microstructural modification on superplastic deformation characteristics of a rapidly solidified (RS) Al-3Li-1Cu-0.5Mg-0.5Zr (wt pct) alloy. This Al-Li alloy has a very fine grain structure desirable for improved superplasticity. The results of superplastic deformation indicated that the alloy exhibited a high superplastic ductility, e.g., elongation of approximately 800 pct, when deformed at temperatures above 500 °C and at the strain rates of 10−2/s to 10−1/s. Such a high strain rate is quite advantageous for the practical superplastic forming application of the alloy. Stress-strain rate curves were obtained by performing a series of load relaxation tests in the temperature range from 460 °C to 520 °C in order to examine the superplastic deformation behavior and to establish its mechanisms. The stress-strain rate curves could be separated into two parts according to their respective physical mechanisms, i.e., grain matrix deformation and grain boundary sliding, as was proposed in a new superplasticity theory based on internal deformation variables. The microstructural evolution during superplastic deformation was also analyzed by using transmission electron microscopy. During superplastic deformation, grains were kept fine and changed into equiaxed ones due to the presence of fine secondary phase particles and the continuous recrystallization due to the development of subgrains. Consequently, the rapidly solidified (RS) alloy showed much improved superplasticity compared to the conventional ingot cast 8090 alloy.

The improved microstructures and properties of 7075 alloys produced by a water-cooling centrifugal casting method

A centrifugal water-cooling casting method was used to cast a 7075 alloy with the aim of refining the grain and inclusion size and improving mechanical properties in the wrought condition. Con-ventional ingot casting methods were also used and investigated for comparison with the centrifugal casting method. The results show that by the centrifugal casting method, a small equiaxed grain size, 17 μm, is obtained in as-cast condition. Only 50 minutes are required for material homogenization. After rolling to obtain sheet, a grain size of 15 × 8 × 6 μm and an inclusion size of 2 to 3 μm are achieved. Fine-grained centrifugal-cast 7075 alloy exhibits higher strength than the ingot-cast one in the early stages of aging but poorer in the latter stages. However, its ductility and combination of strength and ductility is superior to the ingot-cast ones at all aging times. The reduction in strength in the latter aging stages for the fine-grained structure arises from its higher volume fraction of soft precipitate free zones. The improved ductility is attributed to the higher fraction of transgranular fracture, higher transgranular fracture strain, and intergranular fracture strain. Fine-grained 7075 alloy also displays significant improvements in the exfoliation corrosion resistance. These improvements are related to the increased density of attacking sites on the surface and the increased turns for crack propagation along grain boundaries.

The cast structure of a 7075 alloy produced by a water-cooling centrifugal casting method

A water-cooling centrifugal casting method was applied to cast the 7075 Al alloy to generate a much finer cast structure than that produced by conventional ingot casting methods. The effects of casting parameters, i.e., rotation speed, pouring temperature, water flow, and grain refiner, on casting structure were systematically studied so that the optimum casting condition and the solidification mechanism could be established. The typical cast structure along the thickness direction of a cast ring could be divided into four equiaxed zones, including the chill zone which is in contact with the mold wall. All zones have their characteristic grain size, morphology, and relative thickness, which are all dependent on the casting condition. The optimum casting condition yielding the finest structure available was found to be 3000 rpm, 650 °C, and sufficient water cooling. A uniform portion occupying 90 pct of the whole thickness and having a grain size of 17 μm could be achieved under such a casting condition. When a grain refiner was added, the whole ring became further concentrated with grains of fine structure. A mechanism concerning the overall effects of rapid solidification, turbulent flow, and centrifugal force has been proposed for the present casting method and might explain the zone-structure formation and the effects of the casting parameters on microstructural features.

急冷凝固過共晶 Ａｌ−Ｓｉ合金の被削性

In casting of a hypereutectic Al-Si alloy, silicon is generally known to crystallize easily as a needle or plate-like shape in the matrix, resulting in the decreased machinability as well as the decreased mechanical strength and ductility. In this work hypereutectic Al-20 mass%Si alloys were fabricated using both the conventional ingot casting and rapid solidification processes in order to investigate their fundamental aspects of machinability. In the alloy produced by the rapid solidification process (R. S. P) the average size of silicon crystals was smaller than that in the alloy produced by the conventional casting process and both the mechanical strength and hardness increased. The tool wear and surface roughness of the R. S. P. alloy were superior to those of the conventional casting process alloy. The cutting force for the R. S. P, alloy was higher than that for the conventional process alloy. The chip treatability of the conventional casting process alloy was better than that of the R. S. P. alloy in the case that no chip breakers were used.

Effect of extrusion parameters on properties of rapidly solidified Al–Mg powder alloys

Three rapidly solidified Al–Mg powder alloys have been consolidated by means of cold compaction followed by hot extrusion. The extrusion conditions of temperature, reduction ratio, and ram speed were varied, and it was observed that the mechanical properties of the extrudates were strongly process related. Relationships between properties and the temperature compensated strain rates during extrusion have been established. These alloys have strength/density properties superior to the strongest conventional ingot cast alloys. Good fracture toughness has been recorded in the Al–7 Mg alloy and all three alloys possess good resistance to stress corrosion cracking.MST/498

A simple construction of the AlCuLi quasicrystalline structure related to the (Al, Zn)49 Mg32 cubic structure type

Abstract Both b.c.c. and icosahedral AlCuLi phases coexist following conventional ingot casting. Owing to a slight difference in their composition, they can be distinguished by a Z-contrast technique in a scanning electron microscope. Moreover, the existence of an orientation relationship between the b.c.c. and icosahedral (AlCuLi) phases is established by a transmission electron microscopic study of an ion-beam-thinned sample. It is therefore confirmed that a close structural relationship exists between both AlCuLi phases. A simple construction of the AlCuLi quasicrystalline structure is proposed on the basis of a modified illustration of the Bergman-Waugh-Pauling–type structure, Im3 (AlCuLi), isostructural with (Al,Zn)49Mg32, which reveals that triacontahedra—known to be the basic volume element of the three-dimensional Penrose tiling—exist in these cubic phases. A simple change of the coordination number between triacontahedra is considered to initiate the construction of the corresponding icosahedral ...

The Energy Savings in Reroll Casting From Primary Metal

Recent developments in the continuous casting of strip by belt casting, associated with the primary production of aluminum, offer substantial advantages in energy saving, through the direct conversion of molten metal into strip and through the reduction of melt loss. The total energy content (electrical and thermal) of the continuous casting route is compared to that involved in the conventional ingot casting and hot-rolling route for a typical semi-fabricated product.

Directionality of mechanical properties in hot-rolled steel plates

Details are presented of directionality in the mechanical properties in hot-rolled steel plates made via BOS steelmaking and conventional ingot casting. The main causes and degree of directionality are outlined. Some difficulties caused by directionality are illustrated. First, the problems in achieving the transverse impact requirements in a number of 9% nickel steel specifications are presented. The directionality of impact properties, the steel specifications, the heat-treatment response, the uses, and the demand for this steel are considered. The importance of elongated non-metallic inclusions and the effect of increased cross rolling on the transverse impact properties are confirmed. Secondly, work carried out to give a limited improvement in through-thickness ductility in ordinary structural steel plate is described. Several steelmaking, rolling, and compositional variables were examined. A number of significant relationships have been established between the through-thickness ductility and the production conditions.