The invention relates to a low-alloyed and high-strength Q and amp of a C-Mn-Al
system; P steel; and a manufacturing method thereof, which belong to the technical field of
metal materials. The method comprises the following
processing steps of: (1)
smelting and cast blocking: the
mass percentages of the components are as follows: 0.16 percent to 0.25 percent of C, less than or equal to 0.40 percent of Si, 1.20 percent to 1.60 percent of Mn, 1.0 percent to 1.5 percent of Al, less than or equal to 0.02 percent of P, less than or equal to 0.008 percent of S and the balance of ferrite. (2) rolling: after the multi-pass hot-rolling of rough rolling and finish rolling, wherein, the deformation of roughing pass is 10 percent to 30 percent, the total deformation of the finish rolling is more than 60 percent, a
hot rolled plate is subjected to multi-pass cold rolling, the deformation is 5 percent to 50 percent, and the plate is rolled to be a thin plate with the thickness being 0.6 to 2.0mm. (3)
heat treating: firstly, austenitizing of 850 to 930 DEG C is carried out in a
heating furnace, temperature is kept for 100 to 200 seconds and then rapid
quenching is carried out to reach 230 to 250 DEG C, the temperature is kept for 20 to 40 seconds, after that the temperature is kept in 300 to 400 DEG C for 120 to 3600 seconds, at last fast cooling is carried out to
room temperature (the speed of the cooling is not less than 10 DEG C / s). The Q and amp and the P steel have economic components, good quality of the surface, high strength and good shaping resistance. The strength and
ductility product can reach over 37000MPa
question mark percent.