Hot rolling process for producing low-temperature impact work railway bridge steel

Abstract

The invention relates to smelting and hot rolling processes of steel in the field of ferrous metallurgy and particularly relates to a hot rolling process for producing low-temperature impact work railway bridge steel. The low-temperature impact work railway bridge steel comprises the following components in percentage by mass: 0.15%-0.17% of C, 0.15%-0.30% of Si, 1.35%-1.45% of Mn, P is less than or equal to 0.020%, S is less than or equal to 0.005%, 0.020%-0.055% of Alt, 0.015%-0.035% of Nb. CEV is less than or equal to 0.43% and the balance of Fe, wherein precious metal Ni is not added. The hot rolling process comprises the steps of in the converter, carrying out LF and VD in turn, or carrying out RH, continuous casting and hot rolling in turn so as to obtain the low-temperature impact work railway bridge steel having low-temperature impact work of more than 120J at -40 DEG C, wherein the impact work actual product level at -40 DEG C can reach above 200J. By virtue of use of the hot rolling process, the strength, plasticity and low-temperature impact index of steel of a controlled rolling process meet the requirements, the production time of the procedure is short, the production efficiency is high, the machine yield of a rolling machine is decreased, and the cost is lowered.

Description

technical field [0001] The invention relates to iron and steel smelting and hot rolling processes in the field of iron and steel metallurgy, in particular to a hot rolling process for producing low-temperature impact energy railway bridge steel. Background technique [0002] In recent years, as the state has increased investment in the basic transportation industry, in terms of railway bridges, the state has proposed in the "Medium and Long-term Railway Network Planning" that by 2020, the national railway operating mileage will reach 100,000 kilometers, and the plan is four vertical and four The construction of the horizontal railway bridge project is about 5,000 kilometers, and it is estimated that the railway bridge slab is about 300,000 tons per year. Railway bridges are usually designed with steel structures, which put forward high requirements for the strength and toughness, welding, yield strength ratio, and Z direction of steel structures, especially for low temperatu...

AI Technical Summary

Problems solved by technology

According to the technical requirements of the railway bridge standard -40°C impact energy greater than 120J, under the original composition and process conditions, the pass rate of -40°C impact energy of 3500mm coil and 2800mm plate unit is only 66% and 67%, respectively, and the pass rate of individual specifications is insufficient 60%, which cannot meet the requirements for the use of railway bridge steel