There are also the thermal stresses and strains that occur as the part changes temperature. There are also other volume changes that occur as austenite transforms to ferrite, pearlite, and bainite. For instance, there is a volumetric change that occurs as austenite transforms to martensite. Mechanical data are the elastic and plastic strains and stresses that occur as the part is quenched. Measured data is always preferred of calculated data. Much of this data is either determined by metallurgical examination using a Gleeble or can be calculated using software. This data is needed as a function of temperature. This data can be measured directly or calculated from chemical data (JMATPro or similar). It is the rate at which the different phases (ferrite, pearlite, and bainite) form for diffusive type of transformations, and the driving force for the non-diffusive martensitic transformation.

This is the basic information that is published in the Continuous Cooling Transformation (CCT) diagrams. Metallurgically, data is needed regarding phase transformations. There are three main areas where properties are needed: metallurgical, mechanical, and heat transfer or thermal. The properties needed to properly model and simulate the heat-treating process are summarized in Figure 2. In each one of these processes, there is data needed to properly calculate the resultant properties, microstructure, and residual stress. Tempering is generally straightforward but may have single or double tempering. Quenching could be in different quenchant, such as gas, oil, or salt, and be either martempering, austempering, or standard quenching. The austenitize step can be a simple through hardening step or it could be a complicated carburizing or carbonitriding cycle. Once the proper boundary conditions and properties of system have been established, an accurate model can be achieved.ДЇocusing on heat treatment, the basic process is austenitize, quench, and temper (Figure 1).

To be successful, an understanding of the data needed is necessary to execute a successful model or simulation. Modeling and simulation are used in forging, casting, machining, forming, and heat treatment.

Examples of microstructure elements are stable or metastable phases (their alignment can be manipulated by synthesis and subsequent thermo-mechanical treatments), texture, stacking faults, interfaces (with and without enrichment of alloying additions), dislocations, and point defects in addition, these вЂњimperfectionsвЂќ contain themselves defects of lower dimensionality and can undergo phase transformations.Modeling and simulation have become an important part of the design and manufacturing toolbox. In contrast to ideal single crystals, advanced materials typically contain a complex microstructure. Fracture toughness, strength, ductility, thermal conductivity, thermal stability, corrosion resistance, electrical conductivity, magnetic coercivity, and magnetic hysteresis are prominent examples of material properties, which we tailor by the extrinsic and intrinsic вЂњarchitectureвЂќ of materials. The interplay of microstructure and properties is at the core of materials science and engineering and is key to design optimized вЂ“ often multifunctional - materials.

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