720MPa-grade magnet yoke steel plate with low internal stress and manufacturing method thereof

Abstract

The invention relates to a 720MPa-grade magnet yoke steel plate with low internal stress and a manufacturing method thereof. The magnet yoke steel plate comprises the following components in percentage by weight: 0.031 to 0.109 percent of C, less than or equal to 0.13 percent of Si, 1.23 to 1.68 percent of Mn, less than or equal to 0.012 percent of P, less than or equal to 0.005 percent of S, 0.061 percent to to 0.152 percent of Ti, 0.049 to 0.072 percent of Nb, 0.011 to 0.091 percent of Mo, 0.002 to 0.003 percent of B, 0.04 to 0.08 percent of Al, less than or equal to 0.007 percent of N, andthe balance Fe and inevitable impurities. According to the magnet yoke steel plate provided by the invention, the yield strength is larger than or equal to 722 MPa, the tensile strength is larger thanor equal to 815 MPa, the ductility A is larger than or equal to 15 percent, the impact energy KV2 at minus 20 DEG C is larger than or equal to 102 J, the magnetic induction performance B50 is largerthan or equal to 1.62 T, and the unevenness is smaller than 3 mm / m.

Description

technical field [0001] The invention relates to the technical field of iron and steel manufacturing and mechanics, in particular to a 720MPa-level magnetic yoke steel plate with low internal stress and a manufacturing method thereof. Background technique [0002] In special key materials such as large-scale hydroelectric units, yoke steel is the key component, which bears a huge moment of inertia. Therefore, the yoke steel plate must be required to have sufficient strength to meet the safety of the use of hydro-generators. [0003] In the industrial production of metal materials, the problem of residual stress is very prominent, including various mechanical processes including extrusion, rolling, drawing, cutting, grinding, surface rolling, shot peening, hammering, assembly, etc. Or heat treatment such as welding, casting, quenching, tempering, etc., will cause varying degrees of residual stress in metal products or workpieces. [0004] In the production process of yoke ste...

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Problems solved by technology

[0006] Due to the poor control of residual stress and plate shape of the existing yoke steel products, the actual yield is very low, and the strength and magnetic induction properties of the existing yoke steel products can meet the requirements, but there is no impact on the residual stress level of the product and the plate shape. Therefore, it cannot adapt to and meet the generator requirements of large-scale hydropower projects; and there is a lack of products with a yield strength between 720MPa and 850MPa in the existing yoke steel products, and products in this range are the areas with the largest existing market volume , so there is an urgent need to add a 720MPa grade yoke steel plate with lower residual stress and higher level of roughness

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