Production method of 830mpa grade bainitic high-strength finish-rolled steel bar

Abstract

The invention discloses a production method of a 830 MPa grade bainite high-strength finish-rolling reinforcement steel. The production method comprises the procedures of metallurgic steel making, steel rolling and heat treatment, wherein the steel making procedure adopts a vanadium and manganese microalloying technology; the steel rolling procedure adopts low-temperature control rolling; and the heat treatment procedure adopts a low-temperature tempering technology. In the smelting process, silicon manganese alloy and silicon iron are matched for alloying, and vanadium iron is used for vanadium microalloying; in the rolling process, the initial rolling temperature and the finish rolling temperature are reduced to guarantee the realization of refined crystalline strengthening and second phase dispersion precipitation strengthening so as to improve the strength; in the heat treatment process, the low-temperature tempering method is adopted; after the tempering is performed, a granular bainite / martensite complex phase structure is generated, and a small quantity of proeutectoid ferrites are synchronously generated; the reinforcement steel has high strength through the bainite / martensite complex phase structure; the plasticity and the toughness of the reinforcement steel can be effectively improved through the small quantity of proeutectoid ferrites; and excellent fitting between the strength and the plasticity of the reinforcement steel is guaranteed through a B / M+IF (a small amount) complex phase structure.

Description

technical field [0001] The invention relates to a production method of steel bars, in particular to a production method of 830MPa grade bainite high-strength finish-rolled steel bars. Background technique [0002] In recent years, buildings have developed in the direction of long-span, high-rise, and complex, and high-strength hot-rolled ribbed steel bars for reinforced concrete have been widely used. Compared with ordinary steel bars, the fine-rolled threaded steel bars have obvious advantages such as easy and safe connection, anchoring, convenient construction, and saving, and better solve the welding problem of steel bars. Large-scale projects in my country put forward higher requirements for the strength level of steel bars. For example, the Three Gorges Project and the Beijing-Shanghai High-speed Railway Project used 1000MPa high-strength steel bars. The increasingly stringent codes for the design of engineering seismic structures have higher and higher requirements fo...

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Problems solved by technology

Using 45Si2MnMoV to produce high-strength finish-rolled steel bars contains expensive Mo and uses controlled rolling and controlled cooling technology, which requires continuous rapid heating, quenching, and rapid tempering. Although the strength of steel bars can be greatly improved, the process is still relatively complicated and the conditions are harsh. , higher production cost

The use of 40Si2MnV to produce high-strength finish-rolled steel bars requires the use of controlled rolling and controlled cooling technology, and the use of waste heat treatment after rolling; waste heat treatment is to pass the steel bars from the exit of the final rolling mill through a special water cooling system, so that the cross-section of the steel bars is quenched into Martensite. Body, the core is still supercooled austenite, in the subsequent cooling process, the heat of the core is transferred to the surface of the steel bar, causing the surface quenched structure to decompose, and through this heat treatment, the steel bar undergoes phase transformation strengthening; High-performance steel bars cannot achieve high-strength and high-plasticity matching problems, and the process is complex, and the steel bars that have been heat-treated after rolling have problems such as uneven performance, high yield-strength ratio, and poor seismic performance.

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