PSI - Issue 72

Aleksandra Krstevska et al. / Procedia Structural Integrity 72 (2025) 172–180

175

essential for ensuring reliability and durability of welded joints in high-temperature applications, such as those found in power plants. Current welds involve buttering one end of the martensitic steel with a suitable filler metal, PWHT and joining to the austenitic stainless steel, Figure 3 [10]. The buttering is used to prevent creation of decarburized zone since carbon moves from the material with low Cr content to material with high Cr content. The filler material is nickel-based alloy, since carbon does not diffuse into the nickel base material.

Figure 3 Buttering of P91 to SS steel [10] 4. Literature review on weld repair without post-weld heat treatment

The cold repair of X10CrMoVNb9-1 steel, a high-performance material widely used in power generation due to its excellent creep resistance and mechanical properties at elevated temperatures, is a critical area of research. Welding X10CrMoVNb9-1 steel without post-weld heat treatment (PWHT) presents several significant challenges that can affect the mechanical properties and long-term performance of the welded joints. These challenges arise from the unique characteristics of X10CrMoVNb9-1 steel, which is designed for high-temperature applications, and the challenges associated with welding processes. The mechanical properties and microstructural changes resulting from welding without PWHT have been extensively studied. Yang et al. (K. Yang et al., 2020) conducted a detailed analysis of the creep crack propagation behavior of X10CrMoVNb9-1 steel weldments under rapid thermal shock conditions associated with repair welding. Their findings indicate that the absence of PWHT can lead to increased susceptibility to cracking, emphasizing the need for careful control of welding parameters to mitigate these risks. The study also highlights the importance of understanding microstructural evolution during the welding process to optimize repair techniques. Residual stresses induced by welding are a significant concern when PWHT is not applied. Yaghi et al. (Yaghi et al., 2020) investigated the residual stress distribution in welded X10CrMoVNb9-1 steel pipes and the effects for mechanical performance. Their research highlights the necessity of addressing residual stresses through alternative methods, such as the use of specific welding techniques or post-weld treatments that do not involve heat. The findings suggest that understanding the residual stress profile is crucial for ensuring the long-term integrity of welded joints in high-temperature applications. Several studies have explored alternative repair methods that do not rely on PWHT. For example, Odanović et al. (Odanović et al., 2013) examined the use of nickel-based electrodes for repair welding of X10CrMoVNb9-1 steel, demonstrating that these materials can provide adequate mechanical properties without requiring high-temperature treatments. The research indicates that emergency repair welding procedures can be effectively implemented as alternatives to PWHT, allowing for timely repairs in critical applications. While the techniques discussed offer promising alternatives to PWHT, challenges remain in ensuring the long-term performance and reliability of repaired components. The potential for cold cracking and microstructural degradation must be carefully managed through the selection of appropriate welding parameters and materials. Further studies are needed to fully understand the implications of these methods on mechanical properties and microstructural stability, ensuring the reliability of repaired components in demanding operational environments.