Estimation of multiple heat-flux components at the metal/mold interface in bar and plate aluminum alloy castings

Abstract

In the present investigation, a serial solution of the inverse heat-conduction problem (IHCP) is extended for Al-3 pct Cu-4.5 pct Si alloy square bars and rectangular plates cast in metal molds. The metal/mold interface was divided into three segments, viz., the half face, the quarter face, and the corner. The heatflux transients during casting solidification were then estimated at these segments. Three configurations were considered, viz., (1) one boundary segment for the whole length on the interface, (2) two boundary segments delineating two heat-flux components, and (3) three boundary segments leading to three heat-flux components. In order to identify the most acceptable spatial distribution of interface heat flux, two types of analyses were performed on the results of the IHCP, viz., convergence of absolute error in the computed and the measured temperatures at the sensor locations and total heat energy transferred across the boundary from the casting to the mold. The error convergence at the thermocouple locations was more or less identical for all the three cases in both bars and plates. However, the total heat absorbed by the mold, in the case of the one-segment model in bars and the three-segment model in plates, was found to be a minimum. This indicated that the interface heat flux did not show any spatial distribution in the case of bars, while a distinct spatial distribution could be identified in the case of plates. The individual heat fluxes at the different interface segments for the plate casting showed a peak within 3 to 3.5 seconds of pouring, after which it reduced and reached stable values in about 200 seconds. The maximum heat flux occurred at the corner segment. The analysis of heat-flux gradients showed that the air gap initiated at the corner and spread toward the center.

Mathematical Modeling of Surface Heat Flux During Quenching

“…The remaining unknown flux components were computed in a similar manner. The inverse algorithm mentioned was used to estimate the interface heat flux in die castings by Prasanna Kumar and Kamath [4] and Arunkumar et al [5] after validating the theoretical model in reference 3.…”

“…[2][3][4][5][6][7][8][9] Prasanna Kumar [3] described a serial solution method for the two-dimensional (2D) inverse heat-conduction problem to estimate multiple heat-flux components and used it to estimate heat-flux components at the metal-mold interface during casting. [4,5] Sarmiento et al estimated the temperature-dependent heat-transfer coefficient during quenching from the measured cooling curves and compared the results of the two computer programs developed for the computation. [6] The heat-flux transients obtained through the inverse technique were more accurate than the Grossmann technique in determining the quench severity of various quenchants; also, it could be used for heattransfer modeling during quenching.…”

Computation of casting solidification feed-paths using gradient vector method with various boundary conditions

“…Lewis and Ransing [23] proposed a correlation and presented that variation in IHTC with respect to interface temperature is exponential in nature. Prasanna kumar and Kamath [24] showed that heat flux at interface depends upon casting geometry. Lewis et al [25] demonstrated the use of finiteelement-method for optimization of feeder shape and volume.…”

Spatial variation of heat flux at the metal–mold interface due to mold filling effects in gravity die-casting

“…However, the spatial variation of air gap and its effect on heat-flux has not been studied in detail. Authors in [17] estimated the spatially varying heat flux transients using a Serial-IHCP-algorithm at the metal-mold interface. They quantified the spatial variation of heat flux in rectangular plate castings.…”

“…The estimation of multiple heat fluxes at the metal-mold interface from the measured temperatures is described in [17]. The basic principle used in this technique is to estimate multiple heat flux components at the surface of the mold wall from the temperatures obtained at the interior points.…”