Production method of high-strength alloy r320cr rail

Abstract

The invention adopts the technical scheme that a production method for high-strength alloy R320Cr steel rails comprises the steps of molten iron desulphurization, converter smelting, LF refining, RH refining, continuous casting and rolling. The production method is characterized in that in the converter smelting step, the content of C in tapped steel is controlled to be 0.01-0.02%, and the tapping temperature is controlled to be 1640-1670 DEG C; in the continuous casting step, constant pulling rate operation is adopted, and the pulling rate is controlled to be 0.6-0.7 m / s; meanwhile, super-weak cooling preparation water is adopted in a secondary cooling section, and the specific water flow is controlled to be 0.15-0.25 L / kg. By adopting the production method disclosed by the invention, the holo-aluminium content in R320cr steel is controlled to be 0.0025%-0.0035%, so that the anti-fatigue ability of the steel rails is improved; the yield of Cr alloy is more than 90%, so that cost is reduced; the heating time of LF refining is 40-50 minutes, and the LF refining can be matched with the continuous casting, so that the production tempo is totally met, and the qualification rate of occluded foreign substance reaches 100%. The extension strength Rm of the obtained R320Cr steel is 1130-1190 MPa; the percentage elongation A after fracture is 9%-12%; and the surface hardness is 325-355 HB, so that a high-quality high-strength alloy R320Cr steel casting blank which can meet product requirements is obtained with low cost.

Description

technical field [0001] The invention relates to metallurgical technology, in particular to a production method of a high-strength alloy R320Cr steel rail. Background technique [0002] The rapid development of railways has put forward higher requirements on the performance and quality of rails, especially in sections with small curve radii or many curves, the commonly used hot-rolled U75V and U71Mn rails show problems such as non-wear resistance and easy damage. In order to improve the performance of rails and extend the life of rails, the development of high-strength and high-hardness rails has become an important issue. Especially in foreign countries, such as Southeast Asia and South America, some countries and regions have high requirements on the hardness of steel rails. Therefore, high-strength and high-hardness R320Cr steel rails have broad market prospects and good economic benefits. [0003] The main chemical composition requirements of R320Cr rail are C: 0.6%~0.8%...

AI Technical Summary

Problems solved by technology

At present, there are the following technical difficulties for R320Cr steel that adopts the process flow of converter smelting-LF refining-vacuum refining-continuous casting: 1) R320Cr steel has the characteristics of high alloy (Cr, Mn), and the amount of alloy is large in the smelting process, and its Compared with the commonly used U75V and U71Mn rails, in addition to requiring low O and low H, the Al content in the steel is also required to be ≤0.004%, because the alloy generally contains a certain amount of Al, which is for steel with 0.8% to 1.2% Cr 2) In the smelting process, due to the large amount of alloy added, the difficulty of process control is large, the production rhythm is slow, and the yield of Cr is low; 3) Due to the high Cr and high C of R320Cr steel, there is a problem of high crack sensitivity of the slab