As a critical component of a train, the railway wagon bogie adapter has higher quality requirements. During the forging process, external loads can induce voids, cracks, and other defects in the forging, thereby reducing its service life. Hence, studying the damage behavior of the forging material, specifically AISI 1035 steel, becomes crucial. This study involved obtaining stress–strain curves for AISI 1035 steel through uniaxial tensile tests at temperatures of 900 °C, 1000 °C, and 1100 °C, with strain rates of 0.1 s⁻¹, 1 s⁻¹, and 10 s⁻¹. Subsequently, SEM was used to observe samples at various deformation stages. The damage parameters, $q_1$, $q_2$ and $q_3$ in the GTN model “a computational model used to analyze and simulate material damage which can effectively capture the damage behavior of materials under different loading conditions” were then calibrated using the Ramberg–Osgood model and stress–strain curve fitting. Image Pro Plus software v11.1 quantified the sample porosity as $f_0$, $f_n$, $f_c$ and $f_F$. A finite element model was established to simulate the tensile behavior of the AISI 1035 steel samples. By comparing the damage parameters of $f_0$, $f_n$, $f_c$ and $f_F$ obtained by the finite element method and experimental method, the validity of the damage parameters obtained by the finite element inverse method could be verified.