902results about How to "Refine the grain size" patented technology

The invention discloses high-toughness hot-rolled high-strength steel with the yield strength being 800 MPa and a manufacturing method of the high-toughness hot-rolled high-strength steel. The chemical components of the high-toughness hot-rolled high-strength steel comprise, by weight, 0.02-0.05% of C, 0-0.5% of Si, 1.5-2.5% of Mn, 0-0.015% of P, 0-0.005% of S, 0.02-0.10% of Al, 0-0.006% of N, 0.01-0.05% of Nb, 0.01-0.03% of Ti, 0.03-0.06% of Nb and Ti, 0.1-0.5% of Cr, 0.1-0.5% of Mo, 0.0005-0.0025% of B, and the balance Fe and inevitable impurities. According to the high-toughness hot-rolled high-strength steel, the design thinking of ultra-low carbon martensite is adopted, the grain size of austenite is refined through compound addition of Nb and Ti, the hardenability and the temper hardening resistance are improved through compound addition of Cr and Mo, and by utilizing the hot continuous rolling technique, ultra-low carbon martensite structures are obtained through direct quenching or the low-temperature coiling technique; the yield strength of the high-strength structural steel can reach 800 MPa, quite excellent low-temperature impact toughness can still be achieved within the temperature range from minus 80 DEG C to room temperature, and the ballistic work can reach over 100 J at the temperature of minus 80 DEG C.