Super-thick steel plate and production technology thereof

Abstract

The invention belongs to the technical field of steel rolling and particularly relates to a super-thick steel plate and a production technology thereof. The super-thick steel plate includes, by weight, 0.31%-0.37% of C, 0.41%-0.59% of Si, 1.42%-1.59% of Mn, less than or equal to 0.007% of P, less than or equal to 0.004% of S, 1.91%-2.16% of Cr, 0.51%-0.63% of Mo, 0.17%-0.29% of Ni, and the balance Fe and inevitable impurities. The production technology includes the technical processes of electric furnace smelting, ladle furnace (LF) refining, vacuum degassing (VD), constant-speed die casting under argon shield, high-temperature demoulding, liquid core rolling, slow cooling, heating, rolling, online quenching and tempering. The Brinell hardness of the steel plate ranges from 291 HB to 329 HB, the value of difference between the surface hardness and the core hardness of the steel plate is smaller than 15 HB, the maximum thickness of the steel plate can reach 430 mm, and the steel plate can meet the I-class flaw detection requirement of the test standard of JB / T4730.3-2005 forge pieces and the requirement for high-quality interiors of high-class super-thick steel plates.

Description

technical field [0001] The invention belongs to the technical field of steel rolling, and in particular relates to an extra-thick steel plate and a production process thereof. Background technique [0002] With the rapid development of my country's plastics industry, plastic products are increasingly developing in the direction of large, complex and precise. In order to adapt to the development direction of plastic products with increasingly large sizes and complex shapes, the requirements for plastic mold steel are becoming more and more stringent. Especially when the thickness of steel for plastic molds increases, the internal quality of plastic mold steel plates is required to be excellent, and even some high-end users require that the ratings of various inclusions should not be greater than 1.5, and the internal defects of ultrasonic flaw detection ≤ Φ2mm equivalent flat-bottomed hole . [0003] At present, the competition for plastic mold steel plates in the domestic mar...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide an extra-thick steel plate and its production process in view of the problem that the plastic mold steel plate currently on the market cannot meet the special requirements for the thickness of the steel plate and the internal quality of the steel plate under this thickness. The billet is directly rolled on the wide and thick plate rolling mill for extra-thick steel plates for plastic molds. At the same time, the key process technical parameters are defined, thereby improving the internal quality of the extra-thick steel plates for plastic molds

The extra-thick steel plate produced by the invention can meet the level I flaw detection requirements of JB / T4730.3-2005 forging testing standard (Φ2mm equivalent flat-bottomed hole), and the maximum thickness of the steel plate can reach 430mm, which overcomes the original "die casting-ingot opening" Billet-reversible rolling mill or ingot forging process" high cost, complex process, poor internal quality, long production cycle, etc.