Method for eliminating surface defects of carbon steel intermediate blank

Abstract

The invention discloses a method for eliminating the surface defects of a carbon steel intermediate blank. The intermediate blank after blooming is subjected to air cooling-heat preservation channel slow cooling-air cooling to room temperature-shot blasting-magnetic particle inspecting-defect point grinding treatment, the intermediate blank after blooming is subjected to heat preservation and slowcooling in a specific temperature zone, waste heat of the intermediate blank is fully utilized, the formation of a surface scale is accelerated, the defect depth of a matrix is reduced, and the surface defect of the matrix is remarkably reduced. According to the method, three steel shots with different granularities are selected for shot blasting, so that the removal of the scale before magneticparticle inspection can be ensured, the surface roughness of the blank is reduced, and the identification rate of the magnetic particle inspection is improved. The grinding process is simplified, theproduction efficiency is greatly improved, the production consumption is reduced, and the generation of dust is reduced.

Description

technical field [0001] The invention belongs to the technical field of steel rolling production, in particular to a method for eliminating surface defects of a carbon steel intermediate slab. Background technique [0002] Carbon steel wire rod is mainly used to produce steel wire and other metal products. The quality of its surface directly affects the broken wire rate of downstream users in the drawing process and the reliability of finished products in service, and the surface quality of wire rod depends on the billet. Therefore, it is very important to improve the surface quality of the billet before rolling. [0003] For products with strict quality requirements, industrial production generally adopts the second-fire process. After the large-section continuous casting slab is opened, the intermediate slab will inevitably have defects such as cracks, scratches, and pits, which will easily cause wire rod defects during rolling. Surface defects (such as surface scars, rais...

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Problems solved by technology

This process significantly improves the surface quality of the billet, but it also brings several problems. First, it affects the production efficiency. The full grinding process takes 0.8 to 1.5 hours per billet; second, it increases the production cost, including increased power consumption, Grinding wheel consumption, labor cost, and low yield; third, it pollutes the workshop environment, and a large amount of dust generated during the grinding process enters the surrounding environment, making it difficult to effectively protect

[0004] Patent CN106425759A describes in detail the method of cleaning the surface defects of spring steel by mechanical grinding wheel, including shot blasting-flaw detection-full peeling-rounding-secondary shot blasting-magnetic particle flaw detection steps. The process is complicated and the production efficiency is low. For deeper Defects also need to increase the amount of grinding; patent CN104141039A details the control of the whole process of billet heating, grinding, and rolling heating, rolling and cooling, and especially proposes that the steel billet should be ground to 2-4mm after billeting, and the amount of grinding is partial. Large, low yield, and a large amount of grinding dust; patents CN107866700A and CN104057382A describe the grinding process and the control method of grinding depth, without considering the cost and environmental pollution of the workshop

As mentioned in the above patents, the method of improving the surface quality of blanks still belongs to the traditional way of relying on mechanical cleaning, which has not effectively improved or solved the above three problems

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