Hot-rolled ferrite bainite dual-phase steel strip for wheel with 590MPa class tension strength and preparation method thereof

Abstract

Provided is a hot-rolled ferrite bainite dual-phase steel strip for a wheel with 590MPa class tension strength. The strip is prepared from, by weight, 0.05-0.10% of C, 0.40-0.70% of Si, 1.40-1.70% ofMn, P less than and equal to 0.020%, S less than and equal to 0.004%, 0.020-0.060% of Al, 0.015-0.035% of Nb, 0.20-0. 40% of Cr, N less than and equal to 0.0060, O less than and equal to 0.0020% and the balance of Fe and inevitable impurities. A preparation method is provided, and the method comprises the the following steps of hot metal pretreatment->converter smelting->LF+RH furnace refining->slab continuous casting->heating->rough rolling and finish rolling->control cooling->rolling->finished product inspection->factory leaving. The 590MPa class wheel steel has stable performance, effectively avoids an unsuited fatigue test which is often encountered in the use of a high-strength wheel steel, cracking of rim welding, thinning of a weld seam and cracking of a center hole of a spoke, andis a material ideal for light weight of the wheel.

Description

technical field [0001] The invention belongs to the technical field of steel product production, and in particular relates to a hot-rolled ferritic bainite dual-phase steel strip for wheels with a tensile strength of 590 MPa and a preparation method of the strip. Background technique [0002] With the continuous development requirements of energy saving and emission reduction and automobile lightweight, the lightweight of wheels has become an urgent development demand of the wheel industry. In order to reduce the weight of the wheel, steel with thinner material and higher strength is bound to be used. As the strength increases, the plasticity decreases, forming is difficult, the sensitivity to fatigue notch increases, and welding is difficult. The tensile strength level of 590MPa is currently the highest strength used in batches in the wheel industry. With the extensive use of this level of high-strength steel, some problems have gradually become prominent. One is the crac...

AI Technical Summary

Problems solved by technology

[0003] The 590MPa grade high-strength steel currently used in the market mainly has three structure types, one is the ferritic pearlite type, the hole expansion rate of this steel is low, and it is easy to cause the center hole of the spoke to crack, which is not suitable for the use of passenger car spokes; Ferritic martensitic dual-phase steel, this type of steel has a low yield ratio and is easy to form. It is widely used in the manufacture of wheel spokes, but this type of steel is not suitable for making rims, because of the softening problem in the welding heat-affected zone, it is easy to appear welds Thinning problem, this kind of steel usually adopts three-stage cooling method in the production process, the temperature and time of the intermediate air-cooling section are not suitable for control, resulting in unstable coil performance, and many users are discouraged; the third is ferritic bainitic dual-phase steel That is, FB steel. This type of steel has a high hole expansion rate and is suitable for the use of passenger car spokes. However, this type of steel usually adopts a three-stage cooling method during the production process, and there is also the problem of unstable coil performance.