S304H steel is used in the construction of pressure components of boilers with supercritical operating parameters. The paper presents the results of research on the microstructure following ageing for 30,000 hours at 650 and 700°C. Microstructure examination was performed using scanning and transmission electron microscopy. The precipitates were identified using transmission electron microscopy. The paper analyses the precipitation process and its dynamics depending on the temperature and ageing time in detail. MX carbonitrides and the ε_Cu phase were proved to be the most stable phase, regardless of the test temperature. It was also showed that the M₂₃C₆ carbide precipitates in the tested steel and the intermetallic sigma phase (σ) may play a significant role in the loss of durability of the tested steel. This is related to their significant increase due to the influence of elevated temperature, and their coagulation and coalescence dynamics strongly depend on the ageing/operating temperature level. The qualitative and quantitative identification of the secondary phase precipitation processes described in the study is important in the analysis of the loss of durability of the tested steel under creep conditions.

The paper shows the degradation process of the modern austenitic Super 304H (X10CrNiCuNb18-9-3) steel which was subjected to long-term aging for up to 50,000 h at 650 and 700°C. The investigations include microstructure examination (SEM), identification and analysis of the precipitation process, and mechanical properties tests. The Super 304H steel has a structure characteristic of austenitic steels with visible annealing twins and single primary NbX precipitates. Long-term aging in the steel leads to numerous precipitation processes of M23C6, MX carbides, σ phase, Z phase, and -Cu phase. Precipitation processes lead to a decrease in plastic properties and impact energy as well as alloy over aging. Yield strength and tensile strength values after 50,000 h of aging were similar to those as delivered. The yield and tensile strength value strongly depend on the applied aging temperature.

The purpose of the paper was to design geometric models of the movable connection made of brass for three different attachment options and three different loads. The numerical analysis of the mechanical properties, stresses, strains and displacements using the finite element method was carried out in SolidWorks 2020 and their comparative analysis was performed. The computer simulations performed will allow the boundary conditions that directly affect the mechanical properties of the engineering materials to be optimised.

Steel-wood-steel connection is widely seen in many applications, such as timber structures. The stiffness of steel-wood-steel connection loaded parallel to grain for softwoods originated from Malaysia was investigated in this study. Numerical models have been developed in ABAQUS to study the stiffness connection. Softwoods of Damar Minyak and Podo have been selected in this analysis. The comprehensive study focused on the effect of bolt configurations on stiffness. Numerical analysis is carried out and the developed model has been validated with the previous study. Further investigations have been made by using the validated model. From this model, numerical analysis of the stiffness values have been made for various bolt configurations, including bolt diameter, end distance, bolt spacing, number of rows and bolts and edge distance. The result shows that the stiffness of bolted timber connections for softwood depends on the bolt diameter, number of rows and bolts, end distance and edge distance. Based on the result, stiffness increased as the diameter of the bolt, end distance, number of rows and bolts and edge distance increased. It is also discovered that the stiffness equation in Eurocode 5 (EC5) is inadequate as the equation only considered parameters which are wood density and bolt diameter. Other connection parameters such as geometry are not considered in the EC5 equation.

Stone mastic asphalt is a gap-graded mix and is usually related to its high bitumen content and its skeleton-like constitution. Although famous for its durability, high resistance to fatigue and rutting, issues such as bleeding and premature aging do occur in the mix since it has a high bitumen content and voids due to its gap-graded structure. In order to encounter these problems from affecting the mix, some instances such as adding additives, rejuvenators and stabilizers into the mixture has been implemented. Nowadays, nano materials are being used in the asphalt mixtures and nano titanium is being introduced as a modifier to the asphalt binder in order to improve the mechanical properties of the stone mastic asphalt mix. The related tests done in order to access the improvement are resilient modulus, dynamic creep, moisture susceptibility and binder drain down. The content of nano titanium used in this research are 1%, 2%, 3%, 4% and 5%. This study is done to assess the mechanical performance of stone mastic asphalt with nano titanium modified binder.