PSI - Issue 72

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

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1. Introduction The field of welding had significant development during the past decades due to the demand for advanced materials and the need for joining these materials for use in various industrial sectors. The joining of dissimilar metals presents a challenge due to the differences in materials properties such as physical and chemical properties. The subject of this paper is the steel X10CrMoVNb9-1, an alloy used in high-temperature applications such as power plants and petrochemical industries. The joining of dissimilar metals requires an understanding of the mechanisms that provide a quality weld, residual stress distribution, microstructural changes, and mechanical properties. The distribution of residual stresses in dissimilar metal welds can influence the structural integrity of the welded joint ( (Madhusudhan Reddy & Venkata Ramana, 2011). Variations in thermal expansion coefficients between the base and weld metals may result in longitudinal residual stresses, which are responsible for the integrity of welded structure, (Suzuki et al., 2012). This emphasize the necessity of controlling welding parameters to mitigate negative effects on the integrity of the weld. According to these developments, Boumerzoug (Boumerzoug, 2021) reviews the potential of laser welding to control brittle phases in dissimilar metal joints, and Winarto et al. (Winarto et al., 2013) investigates the mechanical properties and microstructure of welded dissimilar metals using various techniques. These papers showed that the choice of welding process and filler materials plays a crucial role in determining the mechanical properties of the weld (M. F. Mamat et al., 2015). Microstructural evolution during welding is a critical factor that influence the performance of dissimilar metal welds. Inappropriate welding procedures can lead to reduced corrosion resistance, especially when joining duplex stainless steel to carbon steels (Wang et al., 2012). This is supported by the work of Kadir et al. (Kadir et al., 2022), who presents how welding parameters can influence the macrostructure and mechanical properties of dissimilar metal welds. Understanding these interactions is essential for optimizing welding processes and ensuring the reliability of welded joints in demanding applications. This paper reviews the current welding technology of dissimilar metal weld of X10CrMoVNb9-1 steel with austenitic stainless steel 12X18H12T. An overview of the state-of-the-art in welding technology of X10CrMoVNb9 1 steel and austenitic steel for dissimilar metal welds. Furthermore, a literature review of weld repair without post weld heat treatment is investigated for X10CrMoVNb9-1. An experimental work is done, welds are created with and without PWHT for the martensitic steel. 2. Overview of X10CrMoVNb9-1 (P91) steel X10CrMoVNb9-1, also known as P91 steel, is a enhanced ferritic-martensitic alloy that has gained significant attention in the field of materials science and engineering, particularly for its application in high-temperature environments such as fossil and nuclear power plants. This steel is characterized by its excellent mechanical properties, including high creep resistance, toughness, and oxidation resistance at elevated temperatures, making it suitable for critical components like piping and pressure vessels (Rhode et al., 2020),(Rhode et al., 2021). The chemical composition of P91, which includes approximately 9% chromium, 1% molybdenum, and small amounts of vanadium and niobium, contributes to its desirable properties, in particular, its ability to maintain structural integrity under prolonged exposure to high temperatures (Pandey & Mahapatra, 2017; Skorobogatykh et al., 2015). The microstructure of X10CrMoVNb9-1 steel is a critical factor that influence its properties. It typically consists of a lath martensitic structure, which is formed during the cooling process after heat treatment, Figure 1. This microstructure is known for its high density of precipitates, primarily niobium and vanadium carbonitrides, which enhance the steel strength and toughness (F. Khan et al., 2021; Silva et al., 2020). The heat-affected zone (HAZ) during welding processes can exhibit complex microstructural changes, including the formation of coarse-grained and fine-grained regions, which can affect the creep strength and susceptibility to type IV cracking — a common failure mode in welded joints of X10CrMoVNb9-1, Figure 2 (Akram et al., 2017a; Lee & Maruyama, 2015; Pandey & Mahapatra, 2017).