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In this paper, using high tensile strength and yield strength of hot-rolling acid washing thin steel sheet instead of cold-rolling steel sheet as the vehicle frame is investigated. The high pure and finer grain steel can be obtained by deep deoxidation technology, deep desulfurization technology, low nitrogen and microalloy-technology of Boron/Niobium/Titanium. High yield strength (σs>340 MPa) and high specific elongation hot-rolling thin steel sheet have been produced in the EAF-CSP short flow product line. The mechanical property, shape, surface quality and tolerance of steel sheet after hot-rolling can be controlled by optimizing joining-casting-rolling and controlling-rolling-cooling technology. Based on the forming test, cold-bending test, welding test and fatigue test results, it can be seen that cold-bending property, forming ability and fatigue strength of hot-rolling acid washing steel sheet is better and meet the product requirement of vehicle frame. This investigation can resolve the fracture problems of QUANSHUN vehicle, improve the working life, provide reliable automobile and reduce the production cost.

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