Within the automotive industry, the press hardening process has been increasingly used to manufacture components. The process allows for both ultra high strength as well as good design freedom of the components. The steel is first austenitized, followed by forming and cooling. The work within this thesis was aimed at modeling this process, where variations in the initial microstructure and austenitization parameters were introduced. The steel grade 22MnB5 was utilized throughout the work, with three different initial states being studied, hot rolled, cold rolled, and cold rolled which was soft annealed. Tensile testing was performed for rapidly quenched samples, as well as for samples cooled at lower rates, where mixtures of phases were present in the final microstructures. A phase transformation model was calibrated based on estimated final phase fractions, dilatometry, and EBSD reconstruction of the prior austenite. The effect of the austenitization parameters on grain growth was studied, where a grain growth model based on the average grain size and temperature was implemented. The relationship between the austenitization conditions and mechanical properties was evaluated with bending tests according to the standard VDA 238-100. To study the relationship between the microstructure evolution during cooling and the final tensile properties, 48 samples were heat treated with unique thermal histories. The temperature histories from the heat treatments were supplied to a phase transformation model, which in turn was coupled to a non-linear regression model that estimated the tensile properties. For a martensitic microstructure, there were minor differences in tensile properties for different initial states of the steel, with similar strength, ductility, and anisotropy. For lower cooling rates, the tensile properties and phase transformation kinetics displayed differences with respect to the initial steel. The grain growth was limited for samples heated up to 930 ˚C, and could be modeled based on the average grain size. For a higher austenitization temperature, there were instances of inhomogeneous grain growth. There were only minor effects of the austenitization conditions on the bending properties, with an average bending angle over 90 ˚C for all thermal histories. The estimations of the tensile properties displayed a minor effect of the split between the training and testing data, with an acceptable agreement with the measured properties. The work presented in this thesis can aid in the modeling of the press hardening process, giving insights into the effects of process variations.