阅读说明：本技术 一种螺纹钢的热轧工艺 (Hot rolling process of deformed steel bar ) 是由 赵小军 谷杰 刘芳 于 2020-06-05 设计创作，主要内容包括：本发明提供了一种螺纹钢的热轧工艺,涉及冶金领域,一种螺纹钢的热轧工艺,将钢水铸成钢坯,将所述铸坯热轧制成螺纹钢,热轧分为预热段、加热段和均热段,其中,预热段温度<800℃,加热段温度为1080-1180℃,均热段温度为1100～1220℃；最后,对热轧后的螺纹钢进行热处理。所述热轧带肋钢筋的显微组织为铁素体组织和珠光体组织。本发明生产方法制备的热轧带肋钢筋,屈服强度、抗拉强度和延伸率优良,广泛用于桥梁和汽车箱体。(The invention provides a hot rolling process of deformed steel bar, which relates to the field of metallurgy, and the hot rolling process of the deformed steel bar comprises the steps of casting molten steel into a steel billet, and hot rolling the steel billet into the deformed steel bar, wherein the hot rolling is divided into a preheating section, a heating section and a soaking section, wherein the temperature of the preheating section is less than 800 ℃, the temperature of the heating section is 1080-1180 ℃, and the temperature of the soaking section is 1100-1220 ℃; finally, the hot-rolled deformed steel bar is subjected to heat treatment. The microstructure of the hot-rolled ribbed steel bar is a ferrite structure and a pearlite structure. The hot-rolled ribbed steel bar prepared by the production method has excellent yield strength, tensile strength and elongation percentage, and is widely applied to bridges and automobile boxes.)

1. A hot rolling process of deformed steel bars is characterized in that molten steel is cast into steel billets, the steel billets are hot rolled into deformed steel bars, and the hot rolling is divided into a preheating section, a heating section and a soaking section, wherein the temperature of the preheating section is less than 800 ℃, the temperature of the heating section is 1080-1180 ℃, and the temperature of the soaking section is 1100-1220 ℃; finally, the hot-rolled deformed steel bar is subjected to heat treatment.

2. The hot rolling process of a deformed steel bar according to claim 1, wherein the deformed steel bar contains 0.05 to 0.2 wt% of carbon, 0.2 wt% or less of silicon, 1.5 to 1.7 wt% of manganese, 0.02 wt% or less of phosphorus, 0.01 wt% or less of sulfur, 0.01 to 0.03 wt% of niobium, 0.09 to 0.12 wt% of titanium, and the balance of iron; the microstructure of the deformed steel bar is a ferrite structure and a pearlite structure.

3. The hot rolling process of deformed steel bar according to claim 1, comprising the following steps:

s1: raw materials for producing deformed steel bar are put into a converter for smelting, and are continuously cast into blanks after being refined in a refining furnace; simultaneously, stacking the continuous casting billets, and cooling to normal temperature under a natural condition; after cooling, heating the continuous casting billet to 1200-1300 ℃ by using heating equipment;

s2: putting the continuous casting slab heated in the S1 into a semi-continuous bar mill for rolling, wherein the temperature of a preheating section is less than 800 ℃, the temperature of a heating section is controlled to be 1100-1170 ℃, and the temperature of a soaking section is controlled to be 1100-1200 ℃; after rolling, placing the rolled bar on a cooling bed to cool to normal temperature;

s3: cutting the bar cooled in the S2 by using a multiple length, wherein the cutting temperature is less than or equal to 200 ℃, fixing the length and flattening the bar cut by the multiple length, and then putting the bar into a hopper for heat treatment;

s4: and (4) placing the bar treated in the S3 into a dephosphorization device for dephosphorization, and after the dephosphorization of the bar is finished, sequentially carrying out forming processing, finishing, quality inspection and warehousing.

4. The hot rolling process of deformed steel bar according to claim 1, wherein the deformed steel bar has a yield strength of more than 700MPa, a tensile strength of more than 750MPa, and an elongation of more than 20%.

5. The hot rolling process of a deformed steel bar according to claim 1, wherein the heat treatment of the deformed steel bar comprises: heating the deformed steel bar to 550 +/-20 ℃, and preserving heat for 3-5 hours;

putting the deformed steel bar after heat preservation for 3-5 hours into water for water quenching;

heating the deformed steel bar subjected to water quenching to 450 +/-30 ℃, and preserving heat for 4-5 hours;

and (4) putting the deformed steel bar after heat preservation for 3-4 hours into water for water cooling.

6. The hot rolling process of a deformed steel bar according to claim 1, wherein the deformed steel bar is subjected to dump cooling in air after the cast slab is rolled into a deformed steel bar.

7. Use of the deformed steel bar according to any one of claims 1 to 6 in bridges.

8. Deformed steel bar produced by the production process according to any one of claims 1 to 6.

Technical Field

The invention relates to the field of metallurgy, in particular to a hot rolling process of deformed steel bars.

Background

Under the manufacturing process and the technical level at the present stage, the lightening of the bridge and the rail is an important means for solving the problems of bridge overload, energy conservation and emission reduction. The use of high-strength steel can improve the quality and prolong the service life of the product on the premise of reducing the self weight. At present, 20MnSi is mainly used for domestic bridges, the consumption of high-strength bridges and vehicle bodies is less, and the weight of the bridges is 15-20% higher than that of foreign similar products.

In order to reduce production costs and improve the safety of components, hot rolled steel sheets for high strength bridges and automobile compartments are being developed to gradually increase the schedule, and research work in this regard is being carried out in various large steel mills. For example, Zhao Chong Zhi of Beijing science and technology university invents a preparation method of hot-rolled and acid-washed high-strength steel for automobile compartments; the invention relates to high-strength low-alloy hot-rolled ferrite bainite weathering steel and a production method thereof (CN101660099A), which are invented by the admissible steel of sand steel research institute Co., Ltd., Jiangsu province; maoxinping of Guangzhou Zhujiang iron and Steel Limited responsibility company invents a process (CN1785543A) for producing Ti microalloyed high-strength weather-resistant steel plate by using a thin slab continuous casting and rolling process.

However, since the above method generally adds expensive alloying elements such as Cr and Ni, the cost of the hot-rolled steel sheet is still high. And part of products adopt a thin slab continuous casting and rolling process, bainite or martensite reinforcement is introduced into the structure of a final finished product by low finishing temperature (such as 800 ℃), low coiling temperature (such as 320 ℃) and a conventional cooling process, and the microstructure of the finished products is changed in the processing process, so that the service performance of the products is not ideal.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a hot rolling process of deformed steel bar, which enables the hot rolled ribbed steel to have high obdurability while having lower content of alloy elements through temperature control in the rolling process.

The present invention achieves the above-described object by the following technical means.

A hot rolling process of deformed steel bars comprises the steps of casting molten steel into steel billets, hot rolling the steel billets into deformed steel bars, and hot rolling the steel bars into the deformed steel bars, wherein the hot rolling is divided into a preheating section, a heating section and a soaking section, the temperature of the preheating section is less than 800 ℃, the temperature of the heating section is 1080-1180 ℃, and the temperature of the soaking section is controlled at 1100-1200 ℃; finally, the hot-rolled deformed steel bar is subjected to heat treatment.

Further, the elements of the deformed steel bar comprise 0.05-0.2 wt% of carbon, less than 0.2 wt% of silicon, 1.5-1.7 wt% of manganese, less than 0.02 wt% of phosphorus, less than 0.01 wt% of sulfur, 0.01-0.03 wt% of niobium, 0.09-0.12 wt% of titanium, and the balance of iron; the microstructure of the deformed steel bar is a ferrite structure and a pearlite structure.

Further, the method specifically comprises the following steps:

s1: raw materials for producing deformed steel bar are put into a converter for smelting, and are continuously cast into blanks after being refined in a refining furnace; simultaneously, stacking the continuous casting billets, and cooling to normal temperature under a natural condition; after cooling, heating the continuous casting billet to 1200-1300 ℃ by using heating equipment;

s2: putting the continuous casting slab heated in the S1 into a semi-continuous bar mill for rolling, wherein the temperature of a heating section is controlled to be 1100-1170 ℃, and the temperature of a soaking section is controlled to be 1100-1200 ℃; after rolling, placing the rolled bar on a cooling bed to cool to normal temperature;

s3: cutting the bar cooled in the S2 by using a multiple length, wherein the cutting temperature is less than or equal to 200 ℃, fixing the length and flattening the bar cut by the multiple length, and then putting the bar into a hopper for heat treatment;

s4: and (4) placing the bar treated in the S3 into a dephosphorization device for dephosphorization, and after the dephosphorization of the bar is finished, sequentially carrying out forming processing, finishing, quality inspection and warehousing.

Furthermore, the yield strength of the deformed steel bar is more than 700MPa, the tensile strength is more than 750MPa, and the elongation is more than 20%.

Further, the heat treatment of the deformed steel bar comprises the following steps: heating the deformed steel bar to 550 +/-20 ℃, and preserving heat for 3-5 hours;

putting the deformed steel bar after heat preservation for 3-5 hours into water for water quenching;

heating the deformed steel bar subjected to water quenching to 450 +/-30 ℃, and preserving heat for 4-5 hours;

and (4) putting the deformed steel bar after heat preservation for 3-4 hours into water for water cooling.

Further, after the casting blank is rolled into the deformed steel bar, the deformed steel bar is placed in the air for stacking cooling.

The deformed steel bar prepared by the hot rolling process is applied to bridges.

Has the advantages that:

1. the hot-rolled ribbed steel bar prepared by the production method has excellent yield strength, tensile strength and elongation, particularly the yield strength of the hot-rolled ribbed steel bar is more than 700MPa, the tensile strength is more than 750MPa, the elongation is more than 20 percent,

2. in the heat treatment process, the hot rolled rib steel is quenched firstly and then cooled by water, and the quenching graph is higher than the temperature adopted in the prior art by 40 ℃, so that the content of ferrite in the hot rolled rib steel can be increased, and the strength and toughness of the hot rolled rib steel are further improved.

3. In the embodiment of the invention, the hot-rolled rib steel has low content of alloy elements and high strength and toughness through temperature control in the rolling process, so that when the production process is used for preparing the hot-rolled steel, the hot-rolled steel with high strength and toughness can be obtained even if the content of the alloy elements in the steel is reduced, namely the hot-rolled steel with the same strength and toughness as the hot-rolled steel with high content of the alloy elements can be produced by adopting low content of the alloy elements, thus greatly saving resources for manufacturing the hot-rolled rib steel with high strength and toughness and reducing the production cost.

4. The yield strength of the hot rolled steel plate is more than or equal to 700MPa, and the microstructure is ferrite and pearlite, so that the defect of reduction of the strength of the steel plate caused by the change of the microstructure in the processing (such as welding) process of the steel plate can be avoided, and the hot rolled steel plate can be used for a bridge with the yield strength of 700 MPa. In addition, the production method of the invention adopts niobium, titanium, manganese and molybdenum as main alloying elements, avoids adding noble elements such as Cr, Ni and the like, and reduces the cost of the hot rolled steel plate.

Detailed Description

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to specific situations.