Saleh Alzughaibi

Additive manufacturing (AM) of stainless steel has been gaining industry attention in recent years due to the need to manufacture complex steel components. Many sectors stand to benefit from the design flexibility, customization, and rapid production capabilities of AM. However, the industry’s adoption of this technology remains limited due to concerns about the mechanical integrity and reliability of AM products. This experimental study examines the wear and tribological behavior of Wire Arc Additive Manufactured (WAAM) austenitic stainless steel 316L. Pin-on-disk tests were conducted using a 5 mm tungsten carbide ball under dry sliding conditions at normal loads of 1.5 and 2.5 N and sliding speeds between 0.03 and 0.229 m/s. The results showed that the coefficient of friction remained relatively stable at approximately 0.6, while wear volume generally decreased with increasing sliding speed. Lower normal loads resulted in lower wear volume, whereas the wear factor showed only limited sensitivity to the applied load. Optical microscopy revealed a ferrite–austenite microstructure with residual δ-ferrite that contributes to the observed wear behavior. These findings demonstrate the suitability of WAAM-produced 316L stainless steel for tribological applications requiring stable frictional performance.

Wire Arc Additive Manufacturing (WAAM) has emerged as a cost-effective and high-deposition-rate technique for fabricating large-scale metallic components; however, the complex thermal history inherent to the process leads to heterogeneous microstructures that can significantly influence tribological performance. In this study, the dry sliding wear behavior of WAAM-fabricated austenitic stainless steel 308L (SS308L) was systematically investigated using a pin-on-disk configuration. The influence of applied normal load (1.5–15 N) and sliding speed (0.03–0.229 m/s) on wear volume, specific wear rate, coefficient of friction (COF), and tangential force was evaluated. Optical microstructural observations indicated features consistent with a ferritic–austenitic solidification structure, including regions resembling polygonal ferrite, Widmanstätten ferrite, and austenitic dendritic morphologies. Wear results showed that wear volume and cross-sectional area increased monotonically with increasing load, while the effect of sliding speed was comparatively less significant. The specific wear rate remained on the order of 10⁻⁴ mm³/N·m with minor variations across test conditions. The COF decreased with increasing load up to 10 N, followed by a speed-dependent response at higher loads. The findings demonstrate that load is the dominant factor governing wear behavior in WAAM SS308L, while microstructural heterogeneity may contribute to frictional stability and wear resistance. This study provides valuable insight into the structure–tribology relationship of WAAM stainless steels and supports the optimization of process parameters for wear-critical applications.

The modulus and toughness of rubbers can be improved by incorporating fillers into the rubber matrix. Filled rubbers exhibit a strain‐induced softening phenomenon known as the Mullins effect. Upon deformation, filled rubbers can dissipate strain energy, which results in enhanced resistance to crack growth. An in‐depth understanding of the energy dissipation accompanying crack growth is important for the predictive modeling of rubber fracture. Herein, an experimental study on the fracture toughness of filled and unfilled rubbers with a focus on characterizing the energy dissipation caused by the Mullins effect during crack growth is presented. A particle tracking method is used to measure the nonlinear deformation fields in notched rubber specimens when subjected to monotonic tensile loading. Using the measured deformation fields and an independently calibrated constitutive model, the evolution of stress fields during crack growth is quantitatively evaluated, based on which the energy dissipation and intrinsic toughness are determined with the assumption of steady‐state crack growth. It is found that the filled rubber exhibits more energy dissipation during crack growth than the unfilled rubber. More importantly, the intrinsic toughness of the filled rubber (5000–8000 J m ^{− 2} ) is also much higher than that of the unfilled rubber (150–300 J m ⁻² ).