Process for manufacturing low yield strength ultrafine grain belt steel

Abstract

The present invention discloses making process of low yield/tensile ratio superfine grain band steel, and the making process can lower the yield/tensile ratio of the band steel effectively while ensuring fined grain. The making process includes the following steps: heating the carbon manganese steel billet to 1150-1200 deg.c; rolling in the initial rough rolling temperature of 1050-1150 deg.c, final rough rolling temperature of 1000-1050 deg.c, initial precision rolling temperature of 950-1000 deg.c, and final precision rolling temperature of 830-870 deg.c; fast cooling the rolled band steel to 710-735 deg.c at the cooling speed of 20-40 deg.c/s, slowly cooling for 3-5 sec, and fast cooling to 650-670 deg.c; and winding. The low yield/tensile ratio superfine grain band steel has yield strength of 295-415 Mpa, tensile strength of 460-510 Mpa, elongation of 26-40 wt%, yield/tensile ratio Rel/Rm not greater than 0.80.

Description

technical field [0001] The invention relates to a method for manufacturing strip steel, in particular to a method for manufacturing ultrafine-grain strip steel with a low yield ratio. Background technique [0002] At present, iron and steel materials are still the main body of structural materials. With the development of society and economy, the iron and steel industry is facing more and more pressure to save resources, save energy, and protect the environment. Therefore, a special preparation method for traditional iron and steel materials has been used to greatly improve their comprehensive mechanical properties. It has become the main direction of steel material research. Among them, new technologies such as thermomechanical controlled rolling process (TMCP), compact strip production line (CSP) and strip ultra-fast cooling device (UFC) are used to produce fine-grained or ultra-fine-grained high-strength steel at low cost. Steel is the development direction of the curre...

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Problems solved by technology

[0004] At present, when the hot continuous rolling mill produces ultra-fine-grained strip steel, it usually adopts the front-stage cooling method of one-time rapid cooling to the target coiling temperature after final rolling. This method is difficult to adapt to the phase transition characteristics of ultra-fine-grained steel. It is not easy to obtain uniform ultra-fine grain structure and ultra-fine grain bands with low yield ratio, which has become the bottleneck of the continuous development of ultra-fine grain steel industrialization technology, which has attracted extensive attention from domestic and foreign counterparts

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