Acta Metallurgica Sinica (English Letters) ›› 2016, Vol. 29 ›› Issue (12): 1136-1143.DOI: 10.1007/s40195-016-0504-0

Special Issue: 高温合金专辑(2016-2017)

• Orginal Article • Previous Articles     Next Articles

Effect of Post-weld Heat Treatment on the Microstructure and Corrosion Resistance of Deposited Metal of a High-Chromium Nickel-Based Alloy

Xin-Jie Di1(),Xiao-Qian Liu1,Cui-Xin Chen2,Bao-Sen Wang3,Xiao-Jiang Guo4   

  1. 1. School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
    2. School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
    3. Baosteel Research Institute, Baoshan Iron &Steel Co., Ltd.,Shanghai 200431, China;
    4. National Engineering Laboratory of Transportation Safety of Oil & Gas Pipeline, Langfang 065000, China;
  • Received:2016-06-06 Online:2016-11-22 Published:2016-11-22

Abstract:

The evolution of Cr23C6 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. With the increase in temperature, the morphology of the Cr23C6 carbides at the grain boundaries was transformed from the continuous lamellar-like to the semi-continuous rod-like and then to the discontinuous granular. Besides, the needle-like Cr23C6 carbides precipitated from γ matrix after PWHT at 850 °C. The coarsening kinetics of the needle-like Cr23C6 carbides obeyed the Lifshitz-Slyozov-Wagner law with the growth speed of 4.93 μm3/h in length and 5.56 × 10-3 μm3/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 °C. The results of electrochemical corrosion experiment indicated that the needled-like Cr23C6 carbides impaired the corrosion resistance of DM due to the formation of chromium depletion around the carbides.

Key words: Post-weld heat treatment, Carbide precipitatio, nMorphology evolution, Electrochemical behavior