Metal-mold Interface Research Articles

液滴落下法によるＡｌ‐４．５％Ｃｕ合金とチル・ブロツク間の熱伝達係数測定

Heat transfer coefficient at metal-mold interface during die casting was evaluated by the metal drop method. Solidification time at certain positions of a specimen was measured using thermocouples. It was also numerically calculated under corresponding experimental conditions with different values of heat transfer coefficient. The values of heat transfer coefficient were determined so as for both solidification time to coincide.

Microstructure refinement with forced convection in aluminium and superalloys

The cooling and average local solidification times were determined for slow solidifiation of Al-4.4 wt% Cu alloy under natural convection and under electromagnetically forced axisymmetric rotation during liquid cooling and solidification in graphite moulds. Cooling rates were measured within situ thermocouples. The conditions needed to stabilize the radial temperature gradient with rotation were established. The microstructure size decreased with increasing rotation, as did the local solidification times. The average grain and dendrite size without imposed rotation is coarser near the mould wall compared with the centre of the casting. This trend is reversed with imposed rotation. Rotation also led to a smaller spread of grain and dendrite size at any chosen height of the casting. These results are discussed in relation to existing theories, and several reasons for an improved heat transfer coefficient with rotation are presented. Forced convective solidification was then carried out for various shapes of integral investment cast Nimonic-90 alloy solidifying under modified conditions that prevented columnar grain formation. Similar results to those recorded for the aluminium case were obtained and are presented here. The major conclusion is that observations indicating a reduction of microstructure spacing during forced convection should also consider improved heat extraction at the mould-metal interface.

An instrumentation scheme for multipoint measurement of mould-metal gap in an ingot casting system

An instrumentation scheme is developed for simultaneous measurement of the time-gapwidth history at various locations of the mould-metal interface during solidification in an ingot casting system. Several casting experiments using this instrumentation show the variation of the time of inception of the gap and the variation of the gap size along the height and around the periphery of the ingot surface.

The application of a new solidification heat flow model to splat cooling

This paper outlines how the virtual adjunct method (VAM) of Garcia, Clyne and Prates, describing heat flow in unidirectional solidification, may be applied to splat cooling processes. The model allows finite thermal resistance across the mould-metal interface and leads to explicit solutions which are mathematically exact. Examples are presented showing how the equations may be used to investigate the relationships between melt-substrate properties, operating parameters and local cooling conditions, with particular reference to the treatment of vitrification. A brief outline is given of how closely real systems are likely to conform to the boundary conditions under which the model must be applied. It is concluded that, while numerical treatments may be required if a given system is to be accurately modelled, the VAM equations should prove useful for general examinations of splat cooling characteristics and in assessing the expected effects of changes in design and operational features.

The application of a new solidification heat flow model to splat cooling

This paper outlines how the virtual adjunct method (VAM) of Garcia, Clyne and Prates, describing heat flow in unidirectional solidification, may be applied to splat cooling processes. The model allows finite thermal resistance across the mould-metal interface and leads to explicit solutions which are mathematically exact. Examples are presented showing how the equations may be used to investigate the relationships between melt-substrate properties, operating parameters and local cooling conditions, with particular reference to the treatment of vitrification. A brief outline is given of how closely real systems are likely to conform to the boundary conditions under which the model must be applied. It is concluded that, while numerical treatments may be required if a given system is to be accurately modelled, the VAM equations should prove useful for general examinations of splat cooling characteristics and in assessing the expected effects of changes in design and operational features.

Relation between Structure of Aluminum Ingots and Heat Transfer Behavior at Mold-Metal Interface

Relation between Structure of Aluminum Ingots and Heat Transfer Behavior at Mold-Metal Interface

Heat Transfer Coefficient of the Metal-Mold Interface in the Metal Mold Casting of Copper Alloys

Heat Transfer Coefficient of the Metal-Mold Interface in the Metal Mold Casting of Copper Alloys

Structure of Metal-Mold Interface Reaction Layer in Steel Castings in Various Sand Molds

Structure of Metal-Mold Interface Reaction Layer in Steel Castings in Various Sand Molds

Improved Corrosion Resistance, Reliability, and Integrity of Cast Stainless Alloys

Abstract The trend in recent years has been towards lower and lower carbon levels in corrosion resistant stainless alloys. This has led to a problem of growing significance for suppliers and users of alloy castings, the problem being surface carburization of castings which can result from reactions occurring at the metal-mold interface during casting and solidification. In this study, the nature and extent of surface carburization were determined for stainless alloy castings poured in various mold environments. The effect of surface carburization on the rate and mode of corrosion attack in the Huey and Streicher tests was also determined. Measures are presented for controlling surface carburization through the use of appropriate casting processes.