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A Nb-containing 316LN stainless steel was compressed in the temperature range 900–1200 °C and strain rate range 0.01–10 s−1. The mechanical behavior has been characterized using stress–strain curve analysis, kinetic analysis, processing maps, etc. The microstructural evolution was observed and the mechanism of flow instability was discussed. It was found that the work hardening rate and flow stress decreased with increasing deformation temperature and decreasing strain rate. On the contrary, the efficiency of power dissipation increased with them; Flow instability was manifested as cracking and flow localization; The hot deformation equation and the relationships between deformation condition and dynamic recrystallization grain size and fraction were obtained; For Nb-containing 316LN stainless steel, the favorite nucleation sites for dynamic recrystallization are in sequence of triple point, grain boundary, twin boundary and intragranular deformation band; The suggested processing window is given.

The AP/CAP Steam Generator has the most complex structure in current nuclear power plant forgings. In order to improve material utilization and nozzle Properties, China First Heavy Industries (CFHI) have carried out the study on profile and blocker-type forging for Channel Head. The numerical and physical Simulations verify that the channel head can be forged step by step in profiling dies with 100~150MN hydraulic press. The achievement has been applied firstly in the AP1000 project of Xian Ning 1#. On this basis, the optimizations of forging process and die structure have been completed. Through process optimizations above, the nozzles of different shapes have obtained uniform deformation and the full-size channel head forging (Including main forging and samples) of CAP1400 steam generator has been manufactured successfully. And the mechanical properties indicate that the toughness has been improved obviously and the gas content has been reduced effectively in nozzle regions.

With the Development of Larger Output and Longer Plant Life for Advanced Pressurized Water Reactor Pressure Vessel (APWRPV), Larger and Mono-bloc Forgings must be Necessary. In the researching and manufacturing of CAP1400RPV forgings, China First Heavy Industries (CFHI) Manufactured Mono-bloc Upper Head with Quick-loc and Mono-bloc Lower Head (Combined Part of Transition Ring and Lower Head),reducing the welding process and the mechanical property deference comparing with the traditional manufacturing, Comparing with AP1000 forgings, not only Obtained better Mechanical Properties, but also Reduced Manufacturing cycle of RPV and Nondestructive in-service Inspection due to Elimination of Weld Seams. CHFI will Development Mono-bloc Nozzle Shell (Combined Part of Vessel Flange Nozzle Shell and Inlet/Outlet Nozzles) for Future APWRPV.