Method for producing low-carbon high-sulfur (sulfur-phosphorous) easy-to-cut structural steel continuous casting billet

Abstract

A continuous casting billet of low-carbon and high-sulphur free-cutting constructional steel production method with the following properties: (1) primary smelting: tapping with degree of oxygen activity of 700ppm, adding right amount Al when tapping of 20% and refinery cinder when tapping of 90%; (2) molten steel refining in LF refined-smelting ladle furnace: (A) deoxidising on top of the slag: agitating and blowing argon from bottom with pressure of 0.5MPa and analyzing sample and adjusting components after energizing for 10 minutes; (B) slag refining: adding 58%CaO,11%Al2O3, 9%SiO2 and 8 %MgO to get degree of oxygen activity of 60ppm; (C) closing argon from bottom when temperature of molten steel is 90 Deg.C more than liquidus line temperature, and feeding sulfur core-spun yarn rapidly. (3) continuous casting: (A) casting rate rationally, such as square continuous casting billet with casting rate of 2m / min; (B) roller pressure of every sedan at the end of conticaster is different from that of 10Bar; (C) setting rational continuous casting technical parameter. Continuous casting billet, which is made by steel of many pattern numbers such as 1213 and 1215, possesses the properties of high stabilization of component, good continuous casting, low cost of manufacture, high quality of casting blank (which meets the rolling request of subsequent heat working) and profound economic benefit.

Description

technical field

[0001] The invention relates to a smelting production method of free-cutting structural steel in the metallurgical industry, in particular to a smelting production method of sulfur (or sulfur-phosphorus composite) system free-cutting structural steel. Background technique

[0002] Structural steel (mainly low-alloy structural steel and carbon structural steel) is a common steel variety, and its production process is: killed steel smelting process, plus casting forming (high-temperature molten steel solidification forming). Usually, in the smelting process, in order to improve the purity of the steel (improve the various performance indicators of the steel), strong deoxidation measures (that is, adding strong deoxidation elements to the steel, such as adding aluminum ingots for precipitation deoxidation, white slag diffusion deoxidation, vacuum Carbon deoxidation, etc.) is an essential technical means. There are two methods of solidification and forming of hi...