SUMMARY
Process simulation requires accurate and reliable data for a wide variety of material properties, ranging from thermal conductivity to flow stress curves. Traditionally such data are gathered from experimental sources, which has significant disadvantages in that not all of the required data is readily available, it may be from various sources that are themselves inconsistent, measurement of high temperature properties is expensive, and furthermore the properties can be sensitive to microstructure as well as to alloy composition. Therefore, it is highly desirable to develop computer models that can calculate all relevant material properties required by process simulation.
This paper describes the development of a computer model that can provide many of the properties required by process simulation in multi-component commercial alloys. These properties are wide ranging, including
● Thermo-physical and physical properties (from room temperature to the liquid state), such as density, thermal expansion coefficient, thermal conductivity, Young's/shear/bulk modulii, Poisson's ratio, viscosity, specific heat and enthalpy.
● Temperature and strain rate dependent mechanical properties up to the liquid state, including high temperature strength and flow stress-strain curves.
● Physical and mechanical properties of steels as a function of time, temperature and cooling rate including user-defined cooling profiles.
A key advantage of the present approach is that detailed property information can be obtained for each phase when necessary. The calculations are based on sound physical principles rather than purely statistical methods, thus many of the shortcomings of methods such as regression analysis have been avoided.
The material properties calculated by JMatPro are displayed conventionally but can also be directly exported to FE/FD based casting or forging simulation packages.
INTRODUCTION
Material data is a vital input for finite-element (FE) finite difference (FD) based process simulation. Such data include physical, thermo-physical and mechanical properties, all as a function of temperature. While these properties are relatively easy to measure at room temperature, they become increasingly difficult to determine experimentally at high temperatures. It is therefore of no surprise that lack of material data has been a common problem for all FE simulation packages. To overcome this problem and provide reliable and cost effective data for process simulation, computer-based models are required so that such properties can be readily calculated. The present paper provides background to a new software package JMatPro [1,2,3,4,5] that is able to provide many of the properties required in multi-component alloys, concentrating on three areas:
● Solidification properties critical to casting simulation.
● High temperature strength and stress-strain curves.
● Phase transformations and material properties leading to the prediction of quench distortion in steels.
To make JMatPro's material data more easily used by process modellers, the data can now be organised in such a format that can be directly read by FE simulation packages. Such linking has been successfully developed between JMatPro and casting and forging simulation packages and subsequently extended to heat treatment and welding simulation packages.
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