▎ 摘　　要

NOVELTY - A sun gear of planetary gear reducer comprises 1.5-3.2 wt.%, preferably 2.3 wt.% zinc, 2-4 wt.%, preferably 2.7 wt.% graphene, 0.1-0.3 wt.%, preferably 0.23 wt.% molybdenum, 0.2-0.8 wt.%, preferably 0.5 wt.% zirconium, 0.6-1.3 wt.%, preferably 1.1 wt.% silicon, 0.3-0.4 wt.%, preferably 0.35 wt.% vanadium, 0.2-0.5 wt.%, preferably 0.39 wt.% manganese, 0.8-1.2 wt.%, preferably 0.9 wt.% chromium, and remaining iron. The weight ratio of zirconium to zinc is 0.2-0.25. USE - Sun gear of planetary gear reducer. ADVANTAGE - The sun gear has high hardness, prolonged service life, excellent wear resistance and corrosion resistance, and low thermal expansion rate, and provides planetary gear reducer with improved precision and service life. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for manufacture of the sun gear.