Production of clean high carbon chromic bearing steel

Abstract

A method for manufacturing high-cleaning and high carbon complex bearing steel includes: 1) choosing charging mixture 2) first steel making molten steel by is greater than or equal to 30ton electric furnace a. smelting furnace burden b. running out foaming slag and adding lime c. alloying when steel tapping with 92% tap and >90% level 3) refining molten steel by steel ladle furnace a. cleaning steel ladle and furnace cleaning b. through bottom blowing argon mixing with 60 min, earlier stage argon blowing intensity 0.4Mpa and later stage 0.3Mpa, material adding amount is less than or equal to 8Kg / ton steel c. precipitating and deoxidizing by two-stage aluminum feeding method, adding crystallized silicon powder, fluorite(content of calcium is greater than or equal to 98%) into slag face, and dispersing deoxidizing 4) vacuum furnace treating a. bottom blowing argon 0.3Mpa, 25min, vacuum content is less than or equal to 140Pa b. bottom blowing argon mixing 15min, 0.1Mpa without materials after treating 5) molten steel mould casting under inactive gas a. ingot moulding temperature 70deg.C, runner brick coating b. pouring speed 5.1ton steel / min of ingot body and mouth. It achieves high yield.

Description

technical field [0001] The invention relates to a production method of bearing steel in the metallurgical industry, in particular to a smelting production method of high-carbon chromium bearing steel. Background technique [0002] The cleanliness of the century-old high-carbon chromium bearing steel is closely related to the fatigue life of the bearing (the fatigue life of the bearing is generally determined by the shape, size, quantity and uniformity of the inclusions in the steel.). For a long time (before the 1990s), metallurgists have always regarded the oxygen content as a key indicator to measure the life of the bearing (in the 1980s, the main indicator of cleanliness was the oxygen content in the steel: the lower the oxygen content, the higher the fatigue life of the bearing) , and a lot of research and practical work have been done on reducing the oxygen content. The oxygen content (oxygen activity + oxide inclusions) of high-carbon chromium bearing steel in Japan, S...

AI Technical Summary

Problems solved by technology

[0004] At present, the bearing steel manufacturers that can meet the basic requirements of precision bearing manufacturers for the high cleanliness and purity of high-carbon chromium bearing steel mainly include Japan abroad. Method ("World Metal Bulletin", February 25th, 2003, 3rd edition); Datong Zhiduo Steel Works developed a production method with oxygen content≤5ppm, Ti<≤6ppm according to the EAF-LF-RH-CC process flow (Japan " Electric Steel "Volume 73 No. 1, January 2002, P61), but there is no introduction to detailed technology; and domestic literature reports are only Baosteel Group Shanghai No. Steel smelting production method (Patent No.: ZL01132236.5), which is characterized by the development of a high-carbon chromium bearing steel production method with an oxygen content of ≤7ppm and a titanium content of ≤12ppm according to the DC-LF-VD-IC process flow, ZL01132236. The disadvantages of the 5 invention patent are: although the requirement that the ladle must be cleaned is put forward, the "completely manual cleaning" implemented in the actual operation process is labor-intensive and the cleaning effect is not ideal; secondly, the process of adding materials after vacuuming The chemical balance of steel slag is destroyed, so that the secondary oxidation products (such as Al2O3) in the steel stay in the molten steel due to insufficient floating time; the above factors cause the smelting and production process of ultra-pure high-carbon chromium bearing steel to be unstable, and the success rate is only About 40%, which affects the manufacturing cost; in addition, the 01 132236.5 invention patent has requirements for the capacity of the upper EBT electric furnace, and the small EBT electric furnace with an electric furnace capacity < 60t cannot implement the 01132236.5 invention patent method

[0005] In addition, the above-mentioned high-clean high-carbon chromium bearing steel production methods, whether domestic (reported in patent documents with specific technical solutions) or foreign (only written reports in the form of bulletins), do not involve the control of nitrogen content

It is well known that the nitrogen remaining in high-carbon chromium bearing steel is easy to combine with titanium in the steel to form angular, high-melting titanium nitride inclusions, which seriously affects the fatigue life of the steel; nitrogen content ≤ 0.0055% (that is, 55ppm) It is the bottleneck of the current DC (direct current electric furnace) production process