The paper deals with the actual topic of mechanical properties of 3D prints made from the polymer material rPET-G and its changes. Using this material in additive technology has great potential in the automotive industry. The research evaluates five different post-processing modifications of 3D prints from rPET-G (recycled polyethylene terephthalate-glycol) material produced by the Fused Filament Fabrication technology. The post-processing included the chemical smoothing of the samples using dichloromethane vapors and heat treatment in an annealing furnace. An epoxy resin, a synthetic coating, and a water-based coating were also applied. The standard was represented by samples without post-processing modifications, both in the form of recycled material and in the form of virgin PET-G. The texture of the samples was evaluated according to EN ISO 4287. Furthermore, the moisture absorption of the samples was evaluated using the gravimetric method according to EN ISO 62. The mechanical testing of the samples was carried out using a tensile test (EN ISO 527-2), a three-point bending test (EN ISO 178), impact strength (EN ISO 179-2), and a cupping test (EN ISO 1520). Degradation of the coatings took place using cyclic tests, which used a combination of exposure in a salt fog environment and in a climate chamber. The results of the experiments indicate that heat treatment appears to be a universal post-processing technology, as this method statistically improves not only the mechanical properties but also significantly reduces moisture absorption.

This study evaluates the effects of three mechanical pre-treatment methods on S235JRG2 steel sheets: blasting with a synthetic corundum (F40), blasting with steel shot (S170), and grinding with synthetic corundum (P40). Untreated samples served as a reference. The analysis of mechanical pre-treatments focused on surface integrity, including measurements of surface roughness parameters Ra and Rz (ISO 21920-2) and subsurface microhardness (ISO 6507-1). Zinc coatings were assessed through mechanical testing (cupping test, ISO 1520) and corrosion testing in a neutral salt spray environment (ISO 9227), with results evaluated using digital image analysis. Experimental findings indicate that electroplated zinc deposition rates are influenced by surface roughness, while subsurface microhardness has no significant effect. In contrast, for hot-dip galvanizing, both parameters impact the process. The mechanical properties of electroplated zinc coatings are further affected by steel surface integrity, whereas hot-dip zinc coatings are primarily governed by intermetallic phase formation, making the influence of steel surface integrity statistically negligible. Corrosion testing revealed that blasting with a synthetic corundum is particularly unsuitable, as it leads to numerous inhomogeneities in both coating types, accelerating corrosion degradation.

The paper is focused on analysing the pearlitic steel phase transformations and their influence on the mechanical properties. The intention is to perform a detailed analysis of the heat treatment process using the exact heating temperature and chemical composition to achieve the optimal mechanical properties of the tool. The key area is monitoring and regulating the heat treatment. This technology is constantly undergoing an optimisation process and is an effort to introduce new trends in monitoring phase transformations and processes. The use of non-destructive methods is an adequate tool. The principle is to determine the exact structural phase at a given moment, which can be very difficult when a complex shaped part is heat treated. Which precludes the use of some other methods of phase transformation analysis. Specifically, the determination of the exact moment of finish of the austenitisation process is eminent. The monitoring of these processes will be ensured by both a non-contact pyrometer and also by the AE method with an adequate sensor and waveguide. The resulting structural phases formed after the heat treatment will be evaluated by electron microscopy, followed by the analysis of the mechanical properties of selected steels.