The hydrogenation reactor, which is used in the petrochemical industry, is primarily fabricated from 2.25Cr-1Mo0.25V steel. Due to the addition of strong carbide-forming elements (e.g., vanadium and titanium), the properties of the steel, such as mechanical behavior under high temperature, creep rupture strength, and resistance to hydrogeninduced cracking, are significantly improved. However, reheat cracking sensitivity of the welded joint is increased (Refs. 1, 2). During postweld heat

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... t (PWHT) or service, reheat cracking typically occurs in the weld metal and coarse grain heat-affected zone (CGHAZ), and the reheat cracking sensitivity of the CGHAZ is generally higher than that of the weld metal. Reheat cracking is generally manifested by an intergranular cracking along prior austenite grain boundaries. Finding the crack through conventional, nondestructive examination is difficult. Therefore, reheat