<p>Welded joints can be divided into different material zones, with considerable variation of material properties around the weld toe. The material inhomogeneity influences the local stress and strain of welded joints under monotonic and cyclic loading. This study aims to examine the local stress and strain characteristics of welded joints considering material inhomogeneity. Numerical models with various material zones were developed, and material properties were determined based on hardness. Smooth specimen models were used to analyze stress and strain distributions excluding notch effects. A detailed inhomogeneous model of a welded joint was established based on extensive microhardness measurements around the weld toe and the Kriging interpolation method. Additionally, a homogeneous model and a simplified inhomogeneous model, based on limited measured data, were generated and compared with the detailed inhomogeneous model. Fatigue life was estimated using the Smith, Watson, and Topper method based on the obtained stress and strain. For smooth specimen models, stress concentration occurs at a location where the strain is not significant, and fatigue cracks were most likely to initiate from the base metal. Results from the two simplified models showed deviations from those of the detailed inhomogeneous model, and the limitations of these simplified models are discussed.</p>