A high-precision multi-segmented hot-rolled steel bar graded controlled cooling process method

Abstract

The invention relates to the technical field of steel rolling, and discloses a high-precision multi-segmented hot-rolled steel bar graded controlled cooling process method, which includes the following steps: heating in a heating furnace; continuous rolling; K1 high-pressure rolling; adding a controlled cooling device after rolling ; Rolled piece cooling. This high-precision multi-cutting hot-rolled steel bar graded controlled cooling process cancels the controlled cooling process after intermediate rolling and changes it to the graded controlled cooling process after final rolling to ensure uniform temperature of the rolled piece before splitting, reduce splitting line difference, and improve product precision. , the weight deviation of the cleaning rod is controlled within the range of ±0.5%, ensuring that the qualified rate of the product is 100%, and the hierarchical cooling control process is adopted to effectively avoid the over-centralized cooling of the cooling section, resulting in large uneven temperature difference between the inner and outer cooling of the steel, and quenching on the surface Abnormal structures such as tempering ensure that the metallographic structure of the product is mainly pearlite and ferrite with fine grains.

Description

technical field [0001] The invention relates to a graded and controlled cooling process method, in particular to a graded and controlled cooling process method for high-precision multi-segmented hot-rolled steel bars, belonging to the technical field of steel rolling. Background technique [0002] Small-sized hot-rolled steel bars are mostly produced by the split rolling process to increase output, but the split rolling technology has stricter requirements on billet quality, temperature and control technology, which can easily cause defects such as surface warping, flashing, and large line differences. ; and after the implementation of the new national standard GB / T1499.2-2018, clear requirements are made on the metallographic structure of the product, mainly pearlite and ferrite, tempered martensite and other abnormal structures are not allowed, and strong wear is canceled in disguise Water waste heat treatment of steel bars. [0003] In order to cope with the implementati...

AI Technical Summary

Problems solved by technology

[0002] Small-sized hot-rolled steel bars are mostly produced by the split rolling process to increase output, but the split rolling technology has stricter requirements on billet quality, temperature and control technology, which can easily cause defects such as surface warping, flashing, and large line differences. ; and after the implementation of the new national standard GB / T1499.2-2018, clear requirements are made on the metallographic structure of the product, mainly pearlite and ferrite, tempered martensite and other abnormal structures are not allowed, and strong wear is canceled in disguise Water waste heat treatment steel bar

[0003] In order to cope with the implementation of the new national standard, major iron and steel enterprises in the country basically adopt micro-alloy strengthening processes such as adding V, Ti, and Nb to produce hot-rolled ribbed steel bars, which leads to a sharp increase in the demand for alloys, resulting in rising prices and greatly increasing production costs. , iron and steel enterprises are facing severe pressure to survive, and steel rolling workshops mostly adopt multi-segment rolling process to produce small-sized hot-rolled steel bars, and the middle water is passed through to control the process temperature of the rolled piece. Due to the short distance from intermediate rolling to finishing rolling, the rolling The temperature in the finishing mill is not uniform, resulting in a large difference in the cutting line, and it is difficult to control the size of the product, which affects the use

Images