High-reaming hot-rolled acid-pickling steel plate above 500-MPa level and manufacturing method thereof

Abstract

The invention discloses a high-reaming hot-rolled acid-pickling steel plate above a 500-MPa level and a manufacturing method thereof. The chemical components of steel comprises, by weight, 0.02%-0.07%of carbon, 0.01%-0.06% of silicon, 1.20%-1.40% of manganese, 0.030%-0.050% of aluminum, 0.010%-0.017% of niobium, 0.20%-0.40% of molybdenum, 0.010% of phosphorus, 0.005% of sulphur and the balance iron and inevitable impurities. The manufacturing method comprises the steps that continuously-cast billets with the thickness being 100-230 mm are heated to the temperature between 1160 DEG C and 1200DEG C, and heat preservation is conducted for 3 to 4 hours; the temperature of rough rolling is equal to or lower than 1060 DEG C, the thickness of intermediate billets is between 35mm and 50mm, and the precision rolling finishing rolling temperature is between 820 DEG C and 900 DEG C; forepart rapid continuous laminar cooling is adopted after finishing rolling, the cooling rate is 30-50 DEG C persecond; the coiling temperature is between 500 DEG C and 600 DEG C; and hydrochloric acid is adopted so that through-coiling continuous cleaning can be conducted on steel plate oxide scale, and the range of the pulling-rectifying elongation rate is between 0.5% and 1.5%. The high-reaming hot-rolled acid-pickling steel plate above the 500-MPa level has high-strength and high-reaming properties.

Description

technical field [0001] The invention belongs to the field of metal materials, in particular to a method for manufacturing a high-strength and high-hole-expanding hot-rolled pickled steel plate for auto parts. Background technique [0002] In recent years, with the development of the automobile industry, automobile manufacturers have increasingly higher requirements for the individualization of steel materials. Hot-rolled pickled steel plate is an intermediate product between hot-rolled steel plate and cold-rolled steel plate with high-quality hot-rolled steel plate as raw material. An ideal substitute for cold-rolled steel sheets. At present, in the severe situation of the steel market, the surface quality of hot-rolled pickled steel plates is better than that of hot-rolled steel plates. Compared with cold-rolled steel plates, on the premise of ensuring the use requirements of surface quality, users can effectively reduce procurement costs, which is a profit for steel compa...

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Problems solved by technology

However, the highest tensile strength of the steel plate is 475MPa, and no hole expansion ra

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