Ni-Cr-Mo-V鋼の強度・衝撃特性に及ぼす化学組成と焼戻し熱処理の影響

概要

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To meet the requirements for optimum utilization of power station sites and economic realization of coal fired thermal units, tandem compound 60 Hz 1000 MW large thermal units were developed. One of the most critical items was development of a large-size high strength generator rotor forging with comparable toughness to the conventional rotor forging. Based on the investigation results of existing rotor forging, chemistry optimization was conducted within the specification of conventional turbine generator and low pressure rotor forging by using lab oratory heat materials and 0.28%C-0.25%Mn-4%Ni-1.75%Cr-0.4%Mo-0.12%V high purity steel was selected for the candidate material. Double tempering heat treatment of 550℃ and 580℃ was also developed for increasing the yielding ratio of 0.02% yielding stress to tensile strength to meet the requirements of mechanical properties. According to those laboratory studies, one trial rotor forging with the same diameter as production ones was successfully produced.
社団法人日本鉄鋼協会の論文