Method for preventing cutting delayed cracks of large-thickness low-alloy martensitic steel
A technology for martensitic steel and delayed cracking, which is applied in the field of preventing cutting delayed cracks in large-thickness low-alloy high-strength martensitic steel and preventing cutting delayed cracks in large-thickness low-alloy martensitic steel. It can solve the problem of high cutting efficiency, Delay cracks, disasters and other problems, achieve the effects of flame cutting process optimization, control of micro-crack expansion, and improvement of segregation
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Embodiment 1
[0043] The chemical composition of this example is: 0.22% C, 0.75% Mn, 0.40% Si, 0.22% Ni, 0.50% Cr, 0.15% Mo, 0.008% Ti, 0.017% Nb, 0.032% Al, 0.0012% B, 0.004% S , 0.008% P, the balance is Fe and impurities.
[0044] Production and heat treatment process:
[0045] The molten steel goes through hot metal desulfurization, converter, LF+RH, and continuous casting. During the continuous casting process, the cooling rate is controlled at 4-10°C / s.
[0046] Continuous casting into a 320mm thick billet, the billet is heated in a heating furnace with a soaking temperature of 1235°C and a soaking time of 47 minutes. Out of the heating furnace for TMCP rolling into 70mm thick steel.
[0047] Carry out secondary quenching and tempering heat treatment process on steel. The steps are as follows:
[0048] Initial quenching: heating temperature 940°C, heat preservation 45min, water cooling;
[0049] Secondary quenching: heating temperature 880°C, heat preservation 35min, water cooling...
Embodiment 2
[0055] The chemical composition of this implementation case is: 0.18% C, 1.21% Mn, 0.50% Si, 0.15% Ni, 0.62% Cr, 0.019% Ti, 0.032% Al, 0.0015% B, 0.004% S, 0.009% P, and the balance is Fe and impurities.
[0056] Production and heat treatment process:
[0057] The molten steel goes through hot metal desulfurization, converter, LF+RH, and continuous casting. During the continuous casting process, the cooling rate is controlled at 4-10°C / s.
[0058] Continuous casting into a 260mm thick billet, the billet is heated in a heating furnace with a soaking temperature of 1230°C and a soaking time of 40 minutes. Out of the heating furnace for TMCP rolling into 50mm thick steel.
[0059] The steel is subjected to secondary quenching and tempering heat treatment process. The steps are as follows:
[0060] Initial quenching: heating temperature 930°C, heat preservation 42min, water cooling;
[0061] Secondary quenching: heating temperature 870°C, heat preservation 28min, water coolin...
Embodiment 3
[0067] The chemical composition of this implementation case is: 0.25% C, 0.98% Mn, 0.30% Si, 0.12% Ni, 0.53% Cr, 0.046% Nb, 0.032% Al, 0.0017% B, 0.0043% S, 0.009% P, and the balance is Fe and impurities.
[0068] Production and heat treatment process:
[0069] The molten steel goes through hot metal desulfurization, converter, LF+RH, and continuous casting. During the continuous casting process, the cooling rate is controlled at 4-10°C / s.
[0070] Continuous casting into a 260mm thick billet, the billet is heated in a heating furnace with a soaking temperature of 1220°C and a soaking time of 40 minutes. Out of the heating furnace for TMCP rolling into 50mm thick steel.
[0071] The steel is subjected to secondary quenching and tempering heat treatment process. The steps are as follows:
[0072] Initial quenching: heating temperature 927°C, heat preservation 40min, water cooling;
[0073] Secondary quenching: heating temperature 875°C, heat preservation 30min, water cooli...
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