Medium-high carbon hot-rolled steel strip with excellent fine blanking property and production method

Abstract

The invention discloses medium-high carbon hot rolled strip steel with excellent fine blanking performance and a production method. The strip steel comprises chemical components in percentage by weight as follows: 0.50%-0.65% of C, 0.60%-1.50% of Si, 0.50%-1.70% of Mn, 0.0030%-0.0070% of Ca, 0.0008%-0.005% of B, 0.015%-0.030% of Als, smaller than or equal to 0.015% of P, smaller than or equal to 0.008% of S and the balance of Fe and inevitable impurities. According to the principle that the activity of carbon atoms in austenite is improved by the Si element, a fast spheroidizing annealing technology is adopted, the heat preservation time is shortened to 1h-2h at the annealing temperature, the cost is reduced, the energy is saved, and the hot rolled strip steel with the excellent blanking performance is obtained finally and is suitable for producing automobile part raw materials with complex shapes and quench hardening requirements.

Description

technical field [0001] The invention relates to the technical field of steel for auto parts, in particular to a medium-high carbon hot-rolled steel strip with excellent fine blanking properties and a production method. Background technique [0002] Modern auto parts such as gears, gearboxes, shift forks, leaf springs and other structures with complex shapes have gradually changed from the previous methods of casting, cutting, heat treatment, and finishing to one-time punching with materials with excellent punching properties. forming. The characteristics of the steel plate with excellent punching performance are: (1) suppress the material cracks at the cutting edge of the die, and obtain a shear surface with a processing surface of more than 85%; (2) good dimensional accuracy; (3) uniform and appropriate hardness, that is, It can't be too high to reduce the life of the mold, and it can't be too low to cause "knife sticking". It is usually required that the structure is in ...

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Problems solved by technology

[0006] However, the method described in the patent CN 103003463A adopts the slow cooling of the heat preservation cover, the temperature difference between the inside and the outside of the steel coil is large, and the difference in cooling rate is also large, so the yield of the steel strip that meets the performance required by the claim is not high. The obtained spheroidization rate is only above 50%, which is too low for punching steel plate

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