Method for producing high-strength hot rolling valve snail

Abstract

The invention discloses a method for producing a high-strength hot rolling valve snail. The method comprises the following steps of: well controlling melting components of molten steel, carrying out continuous casting on the molten steel to obtain a square blank with the measurement (130*130-170*170)mm<2>, and rolling the square blank in a roughing rolling unit and a medium / pre-finish rolling unit after the square blank is heated to the temperature of 1020 minus or plus 10 DEG C in a heating furnace, wherein the temperature of the blank when entering into a finish rolling unit by virtue of a first water tank is 880 minus or plus 10 DEG C, the final rolling temperature of a terminal rack of the finish rolling unit is 980 minus or plus 10 DEG C after the blank is heated, and the temperatureof a twisted steel when going out from a second water tank is 900 minus or plus 10 DEG C. A valve snail which is formed by wrapping after going out from a wire-feeding machine is fed into a roller bed, the running speed of a first section on the roller bed is 0.45m / s and is increased in the increment of 0.05m / s, and the air output of a bottom blower at the downside of the roller bed and atomized water addition amount of the bottom blower are controlled. The melting components of the steel billet in the production method is based on 20MnSi, the silicon content is in low limiting control, the manganese content is lower than the low limiting control, and no Nb, V or Ti is adopted to carry out micro alloying treatment on the molten steel, thus the production cost is saved, a product with goodmechanical properties is obtained and the method has promotional value.

Description

technical field [0001] The invention relates to a production method of threaded steel bars, in particular to a production method for producing 400MPa grade small-sized high-strength hot-rolled coils with a diameter of ≤10mm on a high-speed wire rolling mill for industrial and civil buildings. Background technique [0002] At present, the domestic method of producing small-sized HRB400 hot-rolled ribbed steel bars with a diameter of ≤10mm in the high-speed wire process is mainly to carry out micro-alloying treatment on molten steel. Generally speaking, micro-alloying of molten steel is to add trace alloying elements. At present, ferro-niobium alloy (Fe-Nb), ferro-vanadium alloy (Fe-V) or ferro-titanium alloy (Fe-Ti) is generally used in the microalloying of molten steel in the steelmaking process, and microalloying elements such as Nb, V or Ti are used. The fine grain strengthening effect and precipitation strengthening effect improve the comprehensive mechanical properties ...

AI Technical Summary

Problems solved by technology

At present, ferro-niobium alloy (Fe-Nb), ferro-vanadium alloy (Fe-V) or ferro-titanium alloy (Fe-Ti) is generally used in the microalloying of molten steel in the steelmaking process, and microalloying elements such as Nb, V or Ti are used. The fine grain strengthening effect and precipitation strengthening effect improve the comprehensive mechanical properties of the product, but because the ferroalloy containing vanadium (V), niobium (Nb) or titanium (Ti) is sintered by the corresponding ore and then sintered by electric furnace or submerged arc furnace Smelted, its production process is long, energy consumption and cost are high, and it pollutes the environment; at the same time, in the process of molten steel microalloying, the requirements for the control of molten steel smelting, deoxidation and alloying processes are high, which is not an ideal screw thread Steel production method; in addition, there is also the effect of adding nitrogen-containing niobium-nitrogen or vanadium-nitrogen mixed pellets into molten steel, which can also achieve the effect of microalloying treatment of molten steel. As a general rebar production enterprise, it is a cost increase production method

As far as we know, when rolling 400MPa-grade rebar with a material with a composition of less than 20MnSi, the domestic bar line adopts a strong water-through cooling process, which is to quench and self-temper the surface of the steel bar, and obtain tempered martensite on the bar surface structure to increase its yield strength, but high-speed wire rod mills cannot achieve this process

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