A 2D computational model of single and simultaneous dual frequency induction hardening has been developed. Process specific aspects such as the nonlinear magnetic material behavior and phase transformation kinetics of quenched and tempered AISI 4140 are considered. Induction surface hardening experiments have been conducted for validation purposes. The measuring methodologies used to extract input data such as the magnetic material behavior, the current, and the effective heating time are presented. Metallurgical characterization and hardness profiles are compared with the results obtained from simulations. The temperature history, hardness depth profile, and hardness distribution are in good agreement

This paper describes simulation of repair welding and heat treatment together with measurements for validation. The possibility to replace global heat treatment with local using induction heating is evaluated with respect to obtained residual stresses. A physically based material model is used in the analyses. The result from the residual stress measurement shows that there are no significant differences between local heat treatment and global heat treatment.

Due to increased competitiveness in the aerospace industry, deeper knowledge of the manufacturing process is needed. It is, for example, known that the microstructure is important for the performance of the components. In order to make a cost effective prediction of a product's final shape and mechanical properties, modelling of the various processes in a manufacturing chain is of interest. The finite element method is the best and most common tool used for this purpose.The main route for manufacturing of structural components in aero engines are either forging, casting or fabrication. During these steps, manufacturing defects such as cracks or voids can occur. Repair welding is then necessary. However, welding changes the microstructure of the material. In order to restore the microstructure, and reduce welding residual stresses an heat treatment of the component is necessary. The heat treatment is usually performed by placing the component in a furnace, i.e. a global heat treatment, although it is only a local region that needs to be restored. One method to perform a local heat treatment is by induction heating.The possibility to replace global heat treatment with local using induction heating has been evaluated in the project, both numerically using the finite element method as well as with validation experiments. Finite element models has also been used in order to simulate induction heating in the manufacturing process chain of stainless steel tubes.The aim of this work has been to simulate a process chain consisting of repair welding and local heat treatment with induction heating. It is then possible to predict deformations as well the residual stress state and the change in microstructure. For this has a material model been developed. It is a dislocation density based flow stress model in which precipitate hardening for alloy 718 is taken into account.

The possibility to use induction heating for local heat treatment of aerospace components is evaluated in an on-going project. This paper describes validation measurements and simulations of induction heating of an axisymmetric rod made of alloy 718. The model was found to agree well with experimental data. Furthermore, an approach combining finite element code with a control algorithm for the current has been implemented and is described. This algorithm makes it possible to determine the variation of current needed to create a given temperature history.

The manufacturing process chain at glass-lubricated extrusion of stainless steel tubing is simulated using the finite element method. The developed model includes sub-models of induction heating, expansion and extrusion. An in-house mapping tool is used to transfer the temperature fields between the electromagnetic-thermal and thermo-mechanical analyses. Using the combined model it is possible to study the influence of different process parameters on the temperature distribution in the billet, and how this affects the final extrusion properties. In this study, the model is applied to two cases of tube extrusion, one using an austenitic stainless steel and one using a duplex, austenitic/ferritic, stainless steel. It is shown that the induction heating model successfully predicts the temperatures obtained experimentally from thermocouples placed in the steel billets during heating. The agreement between models and experiments regarding extrusion force and expansion force is satisfactory.

The manufacturing process chain for extrusion of AISI 316L tubes is simulated using the finite element method. Models of induction heating and expansion is included and the temperature field in the billet before extrusion is calculated. It is shown that a correct initial temperature of the billet is needed in order to predict the extrusion force curve in the initial stage of the process.