CN-117286297-B - Method for improving performance uniformity of low-carbon titanium microalloyed steel

CN117286297BCN 117286297 BCN117286297 BCN 117286297BCN-117286297-B

Abstract

The invention provides a method for improving the uniformity of the performance of low-carbon titanium microalloyed steel, which comprises six steps of converter steelmaking, external refining, continuous casting, heating, rolling, cooling and coiling. The finish rolling is carried out at a low temperature, the finish rolling temperature of the finish rolling accords with the following formula ：T min ＝T 0 -△T＝T 0 -[-0.22×([B]×10 6 ) 2 +13.5×([B]×10 6 )-109],T max ＝T 0 -△T+30＝T 0 -[-0.22×([B]×10 6 ) 2 +13.5×([B]×10 6 )-109]+30;, the strip steel is cooled to 650-700 ℃ for coiling by adopting a cooling process of front-stage air cooling and rear-stage weak water cooling. In the invention, a trace amount of B element is added to the molten steel component, and the solid solution and segregation of B at high temperature reduce the degree of mismatching of the interface between the matrix and the precipitate particles, thereby reducing the transformation temperature of austenite to ferrite. Meanwhile, by controlling the low-temperature rolling temperature and the air cooling mode after rolling of the titanium-containing steel, deformation induces a large amount of TiC particles to be separated out, so that the difference of TiC separated out particles in the cooling process after coiling is eliminated, and the uniform and effective control of the performance of the low-carbon titanium microalloyed steel is realized.

Inventors

CHEN SIPING
ZHU YUNJIE
LI MIN
YANG ZHIGANG
HUANG WEILI
WANG XINWEI
ZHANG LIGUANG
DONG GENLAI
NIU YUEWEI
HAO YANLONG
Xu ziqian

Assignees

德龙钢铁有限公司

Dates

Publication Date: 20260508
Application Date: 20230925

Claims (7)

1. A method for improving the uniformity of the performance of low-carbon titanium microalloyed steel is characterized by comprising the following steps: s1, converter steelmaking Adding molten iron into a converter for smelting, and after smelting, adding carbon powder and aluminum-containing materials into the molten steel to adjust the C content and the Al content of the molten steel; s2, refining outside the furnace After tapping, argon is blown in an argon blowing station, silicon-manganese alloy and ferrotitanium are supplemented according to the Mn content of the end point, the Mn content and Ti content in molten steel are adjusted, ferroboron is added in 3 minutes of argon blowing, and the B content is controlled to be 0.0020% -0.0030%; s3, continuous casting Casting molten steel into a blank, controlling the pulling speed to be 1.0 m/min-1.2 m/min, and adopting a forced cooling process in a secondary cooling zone; S4, heating Heating the continuous casting blank in a step-type heating furnace at 1270-1300 ℃ for 120-150 min; S5, rolling The heated continuous casting billet is sequentially subjected to rough rolling and finish rolling, the finish rolling temperature of the rough rolling is controlled to be 1000-1050 ℃, the finish rolling is performed at a low temperature, and the finish rolling temperature of the finish rolling meets the following formula: T min =T 0 -△T=T 0 -[-0.22×([B]×10 6 ) 2 +13.5×([B]×10 6 )-109], T max =T 0 -△T+30=T 0 -[-0.22×([B]×10 6 ) 2 +13.5×([B]×10 6 )-109]+30; in the formula, T min is the minimum value of the finish rolling temperature of the finish rolling, DEG C; t max is the maximum finishing temperature of the finish rolling, C; T 0 is the austenite to ferrite transformation temperature, read by Fe-C phase diagram, ° C; delta T is the reduction amplitude of austenite transformation temperature after composite addition B, ti, and DEG C; [B] b element content in molten steel,%; s6, cooling and coiling And cooling the rolled strip steel and coiling.
2. The method for improving the uniformity of the low-carbon titanium microalloyed steel performance according to claim 1, wherein the molten steel at the smelting end point comprises 0.04-0.10% of C, 0.03-0.15% of Si, less than or equal to 0.025% of P, less than or equal to 0.020% of S and less than or equal to 50ppm of N.
3. The method for improving the uniformity of the low-carbon titanium microalloyed steel performance is characterized by adding carbon powder into molten steel at a ratio of 1.0 kg-1.3 kg per ton during tapping, adjusting the C content of the molten steel to 0.15% -0.20%, adding aluminum-containing materials at a ratio of 0.5 kg-1.5 kg per ton, and adjusting the Al content of the molten steel to 0.15% -0.40%.
4. The method for improving the uniformity of the low-carbon titanium microalloyed steel performance according to claim 3, wherein in the step S2, the silicon-manganese alloy and the ferrotitanium are supplemented, the Mn content in the molten steel is adjusted to be 0.40% -0.80%, the Ti content is adjusted to be 0.04% -0.05%, and [ Ti ] > 5[N ] +0.025%.
5. The method for improving the uniformity of the low-carbon titanium microalloyed steel performance according to claim 1, wherein the specific water content in the step S3 is 0.70L/kg-0.75L/kg.
6. The method for improving the uniformity of the low-carbon titanium microalloyed steel performance according to claim 1, wherein in the step S6, the rolled strip steel adopts a cooling process of front-stage air cooling and rear-stage weak water cooling.
7. The method for improving the uniformity of the properties of the low-carbon titanium microalloyed steel according to claim 6, wherein in the step S6, the low-carbon titanium microalloyed steel is cooled to 650-700 ℃ for coiling.

Description

Method for improving performance uniformity of low-carbon titanium microalloyed steel Technical Field The invention relates to the technical field of ferrous metallurgy, in particular to a method for improving the performance uniformity of low-carbon titanium microalloyed steel. Background Titanium has been widely used as an inexpensive microalloying element for reducing the amount of alloy in various steel grades, because it has a function of fine-grain strengthening and precipitation strengthening in steel. At present, in the production process of titanium microalloyed steel, a trace amount of Ti is generally added, on one hand, tiN is formed with nitrogen to prevent austenite grains from growing when heating, original grains are refined when starting rolling, and finally ferrite grains are refined, and on the other hand, very fine particles are formed in ferrite after interphase precipitation or phase transformation, so that a strong precipitation strengthening effect is generated. However, ti-containing steel is sensitive to production process parameters, and is influenced by uneven cooling particularly in the cooling process after rolling and the cooling process after coiling, and the difference of the precipitation amount of fine particles in the middle part and the head and the tail parts of a steel coil easily occurs, so that the performance is uneven, the difference of yield strength reaches 50Mpa, and the difference of elongation is more than 5%. In the prior art, the uniformity of the temperature of the strip steel is improved and the uniformity of the performance of the strip steel is realized by controlling the cooling process after rolling. For example, chinese patent CN202210005319.8 discloses a method for improving uniformity of performance of Ti-reinforced cold-formed high-strength steel, which adjusts coiling temperature of head and tail of strip steel by adopting a U-shaped cooling method to make coiling temperature of head and tail of strip steel higher than setting temperature of normal position, reduces performance fluctuation in length direction, chinese patent CN107983784A discloses a method for improving uniformity of performance of hot-rolled steel plate, which controls sectional cooling and sectional head and tail shielding of steel plate to realize temperature and structure regulation by adopting ultra-fast cooling system to cool hot-rolled steel plate, chinese patent CN202011454833.7 discloses a method for improving uniformity of mechanical performance of micro-alloy high-strength steel hot-rolled steel plate, which increases ring cooling for 40-45h after coiling and controls cooling speed of head, tail and edge in cooling process based on U-shaped cooling. However, in the actual production process, the precise control of the temperature difference of the head, middle and tail is difficult to realize during rolling and cooling of the strip steel, the problems of too fast cooling of the head, tail and side parts and large temperature difference with the middle part exist, and the problems of large fluctuation of the strip steel through plate strength caused by tissue transformation and micro alloy element precipitation after coiling or in the slow cooling process are further affected. Disclosure of Invention In order to solve the problems in the prior art, the invention aims to provide a method for improving the performance uniformity of low-carbon titanium microalloyed steel. In order to solve the technical problems, the invention adopts the following technical scheme: a method for improving the uniformity of the performance of low-carbon titanium microalloyed steel, comprising the following steps: s1, converter steelmaking Adding molten iron into a converter for smelting, and after smelting, adding carbon powder and aluminum-containing materials into the molten steel to adjust the C content and the Al content of the molten steel; s2, refining outside the furnace After tapping, argon is blown in an argon blowing station, silicon-manganese alloy and ferrotitanium are supplemented according to the Mn content of the end point, the Mn content and Ti content in molten steel are adjusted, ferroboron is added in 3 minutes of argon blowing, and the B content is controlled to be 0.0010% -0.0030%; s3, continuous casting Casting molten steel into a blank, controlling the pulling speed to be 1.0 m/min-1.2 m/min, and adopting a forced cooling process in a secondary cooling zone; S4, heating Heating the continuous casting blank in a step-type heating furnace at 1270-1300 ℃ for 120-150 min; S5, rolling And sequentially performing rough rolling and finish rolling on the heated continuous casting billet. The rough rolling finishing temperature is controlled to be 1000-1050 ℃, the finish rolling is performed at a low temperature, and the finishing temperature of the finish rolling meets the following formula: Tmin＝T0-△T＝T0-[-0.22×([B]×106)2+13.5×([B]×106)-109], Tmax＝T0-△T+30＝T0-[-0.22×([B]×106)2+