Method for heat-treating boron steel, and boron steel with high strength and good toughness, and use thereof

Abstract

The disclosure provides a method for heat-treating a boron steel, which includes: carburizing a boron steel on a surface thereof to obtain a carburized boron steel; austenitizing the carburized boron steel at a temperature of 885-895° C. for 25-35 min, to obtain an austenitized boron steel; sequentially subjecting the austenitized boron steel to an oil quenching and a tempering, wherein the oil quenching is performed at a temperature of 55-65° C. for 29-31 min.

1 . A method for heat-treating a boron steel, comprising steps of
 (1) carburizing the boron steel on a surface thereof, to obtain a carburized boron steel;   (2) austenitizing the carburized boron steel obtained in step (1) at a temperature of 885-895° C. for 25-35 min, to obtain an austenitized boron steel; and   (3) sequentially subjecting the austenitized boron steel obtained in step (2) to an oil quenching and a tempering,   wherein the oil quenching is performed at a temperature of 55-65° C. for 29-31 minutes.   
     
     
         2 . The method for heat-treating the boron steel as claimed in  claim 1 , wherein the boron steel in step (1) has a chemical composition comprising 0.30-0.36 wt % of C, 1.20-1.50 wt % of Mn, less than 0.40 wt % of Si, 0.0008-0.005 wt % of B, 0.30-0.60 wt % of Cr, ≤0.025 wt % of P, ≤0.015 wt % of S, ≥0.015 wt % of Al, 0.020-0.050 wt % of Ti, and a balance of iron. 
     
     
         3 . The method for heat-treating the boron steel as claimed in  claim 1 , wherein carburizing the boron steel on the surface thereof in step (1) comprises a soaking period, a carburazing period, and a diffusion period. 
     
     
         4 . The method for heat-treating the boron steel as claimed in  claim 3 , wherein the soaking period is performed at a temperature of 915-925° C. for 25-35 min, and a carbon potential for the soaking period is in the range of 0.9-1.1 wt %. 
     
     
         5 . The method for heat-treating the boron steel as claimed in  claim 4 , wherein the soaking period is performed at 920° C. for 30 min, and the carbon potential for the soaking period is 1.0 wt %. 
     
     
         6 . The method for heat-treating the boron steel as claimed in  claim 3 , wherein the carburazing period is performed at a temperature of 915-925° C. for 595-605 min, and a carbon potential for the carburazing period is in the range of 1.05-1.25 wt %. 
     
     
         7 . The method for heat-treating the boron steel as claimed in  claim 6 , wherein the carburazing period is performed at 920° C. for 600 min, and the carbon potential for the carburazing period is 1.15 wt %. 
     
     
         8 . The method for heat-treating the boron steel as claimed in  claim 3 , wherein the diffusion period is performed at a temperature of 915-925° C. for 345-355 min, and a carbon potential for the diffusion period is in the range of 0.95-1.15 wt %. 
     
     
         9 . The method for heat-treating the boron steel as claimed in  claim 8 , wherein the diffusion period is performed at 920° C. for 350 min, and the carbon potential for the diffusion period is 1.05 wt %. 
     
     
         10 . The method for heat-treating the boron steel as claimed in  claim 1 , wherein in step (1) the carburized boron steel comprises a carburized layer with a thickness of 1-2 mm. 
     
     
         11 . The method for heat-treating the boron steel as claimed in  claim 1 , wherein austenitizing the carburized boron steel in step (2) is performed at a temperature of 888-892° C. for 28-32 min. 
     
     
         12 . The method for heat-treating the boron steel as claimed in  claim 11 , wherein austenitizing the carburized boron steel is performed at 890° C. for 30 min. 
     
     
         13 . The method for heat-treating the boron steel as claimed in  claim 1 , wherein the oil quenching in step (3) is performed at a temperature of 58-62° C. for 30 minutes. 
     
     
         14 . The method for heat-treating the boron steel as claimed in  claim 1 , wherein the tempering in step (3) is performed at a temperature of 160-170° C. for 115-125 min. 
     
     
         15 . The method for heat-treating the boron steel as claimed in  claim 14 , wherein the tempering is performed at 165° C. for 118-122 min. 
     
     
         16 . A boron steel with high strength and good toughness prepared by the method for heat-treating the boron steel as claimed in  claim 1 . 
     
     
         17 . (canceled)