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This study demonstrates the successful fabrication of a multi-material 18Ni(300) maraging steel – CoCrMo alloy using laser powder bed fusion (L-PBF), which in its as-built state, displays suboptimal mechanical performance. Addressing this, we propose different heat treatments that mutually enhance the properties of both alloys. Comparative analysis of texture development, precipitation sequence and mechanical properties of the dual structures at different scales has been conducted. The results indicate the cooperative strengthening of intragranular γ–ϵ transformation in CoCrMo, and Ni3Ti precipitation in maraging steel. Adding the solution treatment also balanced the formation of acicular Ni3Ti clusters with (Fe, Ni, Co)2(Ti, Mo) precipitates, and revealed that chemical segregation influences austenite reversion. Initial evidence of local grain variant selection has been revealed in as-built samples due to thermal cycling and austenite reversion, which generates residual stresses, recoil forces and convective flow. Surprisingly, the missing variants can also be inherited after heat treatment with insufficient solution temperatures.

Martensitic stainless steels are indispensable alloys in various high stress and temperature applications such as plastic injection molds and components in steam generators. Subtractive manufacturing methods used to fabricate these parts, however, limits its functionality and performance due to design constraint of cooling channels. This limitation can be resolved by means of additive manufacturing while ensuring that acceptable high-temperature properties can be achieved. In this work, the mechanical behavior of additively manufactured 420 stainless steel (AM420SS) is explored through material constitutive modeling to determine the mathematical model that best describes its flow stress in extreme conditions. This is accomplished by subjecting the samples to hot compression under the strain rates of 0.1–1.0 s ^−1 , and temperatures between 973–1423 K (700 °C–1150 °C) via Gleeble thermomechanical test. The experimental data were used to generate the predictive flow stress curves of constitutive models which includes Johnson-Cook, Zerilli-Armstrong, Zener-Hollomon, and Hensel-Spittel equations. Results showed that Zener-Hollomon and Hensel-Spittel models are the most accurate material constitutive equations with relatively high R values of 0.986 and 0.976, and low average absolute relative error values of 6.96% and 7.69%, respectively. The material constants derived from these models can be applied in finite element analysis simulations to assess the performance of using AM420SS parts at high temperature and strain conditions.

Additive Manufacturing (AM) is an advanced technology that has been primarily driven by the demand for production efficiency, minimized energy consumption, and reduced carbon footprints. This process involves layer-by-layer material deposition based on a Computer-Aided Design (CAD) model. Compared to traditional manufacturing methods, AM has enabled the development of complex and topologically functional geometries for various service parts in record time. However, there are limitations to mass production, the building rate, the build size, and the surface quality when using metal additive manufacturing. To overcome these limitations, the combination of additive manufacturing with traditional techniques such as milling and casting holds the potential to provide novel manufacturing solutions, enabling mass production, improved geometrical features, enhanced accuracy, and damage repair through net-shape construction. This amalgamation is commonly referred to as hybrid manufacturing or multi-material additive manufacturing. This review paper aimed to explore the processes and complexities in hybrid materials, joining techniques, with a focus on maraging steels. The discussion is based on existing literature and focuses on three distinct joining methods: direct joining, gradient path joining, and intermediate section joining. Additionally, current challenges for the development of the ideal heat treatment for hybrid metals are discussed, and future prospects of hybrid additive manufacturing are also covered.

Industry 4.0 is seeking to advance traditional construction practices towards more efficient and internet of things (IoT)-based construction practices, such as offsite construction. Offsite construction (OSC) allows for the simultaneous fabrication of building modules and onsite work. Integrating IoT technologies in construction practice is projected to improve the industry’s growth. However, there is an increase in cybersecurity vulnerabilities. Cyber threats are becoming more disruptive and targeted, resulting in monetary and infrastructure losses. Furthermore, the COVID pandemic and the instability in Europe have seen over 100% increases in cyber-attacks, and most industries have weak cybersecurity protocols. The adoption of cybersecurity frameworks in the construction industry is sluggish, and the existing security frameworks fall short in addressing the needs of the industry. This paper gives a concise review of the offsite construction value chain vulnerabilities. We explore the existing cybersecurity frameworks and identify their limitations. Cybersecurity is presented as one of the most crucial components that has received little or no attention in OSC. The future of OSC is promising with the incorporation of Industry 4.0 technologies; however, its development needs to consider more proactive security approaches and management techniques that are adapted to the current hostile cyber landscape.