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The evolution of Cr_(23)C_6 carbides in the deposited metal(DM) of a high-chromium nickel-based alloy was investigated after the post-weld heat treatment(PWHT) at 650,750,850,and 950 ℃,respectively.With the increase in temperature,the morphology of the Cr_(23)C_6 carbides at the grain boundaries was transformed from the continuous lamellarlike to the semi-continuous rod-like and then to the discontinuous granular.Besides,the needle-like Cr_(23)C_6 carbides precipitated from γ matrix after PWHT at 850 ℃.The coarsening kinetics of the needle-like Cr_(23)C_6 carbides obeyed the Lifshitz-Slyozov-Wagner law with the growth speed of 4.93 μm~3/h in length and 5.56 × 10~(-3) μm~3/h in width.Moreover,the ratio of the carbide length to width increased rapidly at first and then flattened as the holding time increased to 850 ℃.The results of electrochemical corrosion experiment indicated that the needled-like Cr_(23)C_6 carbides impaired the corrosion resistance of DM due to the formation of chromium depletion around the carbides.
The evolution of Cr_ (23) C_6 carbides in the deposited metal (DM) of a high-chromium nickel-based alloy was investigated after the post-weld heat treatment (PWHT) at 650,750,850, and 950 ° C, respectively. temperature, the morphology of the Cr_ (23) C_6 carbides at the grain boundaries was transformed from the continuous lamellar to the semi-continuous rod-like and then to the discontinuous granular. Besides, the needle-like Cr_ (23) C_6 carbides precipitated from γ matrix after PWHT at 850 ° C. The coarsening kinetics of the needle-like Cr_ (23) C_6 carbides obeyed the Lifshitz-Slyozov-Wagner law with the growth speed of 4.93 μm ~ 3 / h in length and 5.56 × 10 ~ ( -3) μm ~ 3 / h in width. Core over, the ratio of the carbide length to width increased rapidly at first and then flattened as the holding time increased to 850 ° C .; The results of electrochemical corrosion experiment indicated that the needled-like Cr_ (23) C_6 carbides impaired the corrosion resistance of DM due to the formatio n of chromium depletion around the carbides.