Trial Manufacture of Ni-Cr-Co-based High-temperature Alloy Steel Seamless Tube for Service of 700℃Advanced Ultra Supercritical Boiler

The Φ44.5 mm×10 mm small-sized Ni-Cr-Co based high-temperature alloy steel seamless tube is successfully developed by means of making the blank tube with the process of vacuum induction+vacuum self-consumption+forging+hot-extrusion plus the process of cold-rolling+heat treatment.The testing and inspection results show that the manufacturing processes for the Ni-Cr-Co based high-temperature alloy steel blank tube and the finalized seamless steel tube are reliable,and the finished product has good outer/inner surface quality and high dimensional accuracy;the matrix of the alloy tube presents full austenite structure with rich twinning,and longitudinal average grain size as 72.31μm;and the tube has excellent 25~700℃tensile property,room-temperature impact toughness,hardness and process performance,being satisfactory to relevant operating requirements.