High-strength steel bar and production method thereof

A high-strength steel bar, comprising, by mass percentage, the following chemical components:

• C:
• 0.15-0.32%, Si+Mn:
• 0.5-1.9%, Mn+Cr+Mo+Ni:
• 1.1-2.1%, V:
• 0.02-0.8%, at least one of Nb, Ti and Al:
• 0.01-0.3%, and a balance of Fe and inevitable impurities;
• wherein Mn=(2.5-3.5)Si, and a carbon equivalent satisfies Ceq=C+Mn/6+(Cr+Mo+V)/5+(Cu+Ni)/15≤0.56%;
• a microstructure of the high-strength steel bar comprises ferrite, pearlite, bainite and a precipitated phase;
• the ferrite has a volume percentage of 5-35% and a size of 2-15 μm, the pearlite has a volume percentage of 30-70%, the bainite has a volume percentage of 5-35% and a size of 5-25 μm;
• the high-strength steel bar has a yield strength≥600 MPa, a yield ratio≤0.78, an elongation after fracture≥25%, and an uniform elongation≥15%.