A kind of extra-furnace refining production method of ultra-pure high-carbon chromium bearing steel

Abstract

The invention relates to a secondary refining production method of super-clean high-carbon chromium bearing steel, which comprises the steps of performing processes of KR (Kanbara reactor), BOF (basicoxygen furnace), RS (Rhein Stahl) process, LF (ladle furnace), RH (Ruhrstahl Heraeus) process, CC (continuous casting), and rolling; carrying out further control, to be specific, (1) allowing final sulfur content of hot metal from KR hot metal pretreatment to be < / =0.005%; (2) performing BOF oxygen decarburization, allowing final carbon content to be 0.15-0.80%, adding aluminum of 0.5 kg / t and above into molten steel during tapping according to an aluminum-oxygen balance chart so that oxygen content in tapped steel is dropped to 30 ppm and below, and controlling tapping temperature to 1600-1700 DEG C; (3) after tapping of BOF converter smelting, performing RS slag scraping, and removing slag in a ladle completely; (4) adding refining slag for LF refining, controlling free CaO molecular percent to 40-60% in the refining slag, controlling aluminum content in steel to 0.03-0.07%, controlling oxygen content upon tapping to 10 ppm and below, and allowing tapping temperature to be 1550-1610DEG C; (5) performing argon stirring the whole RH vacuum degassing process, and holding the vacuity of 100 Pa and below for 10 min and longer. The method of the application has the advantages of highefficiency, low cost, and low energy consumption; steel refined via the method is super clean.

Description

technical field [0001] The invention belongs to the technical field of production of ultra-high-quality bearing steel, and in particular relates to an out-of-furnace refining production method of ultra-pure high-carbon chromium bearing steel. Background technique [0002] With the rapid development of the national economy, the application of bearings in our country continues to expand, and the existing key bearings for automobiles and railways generally increase the life and reliability requirements. Bearing life is required to travel more than 2.4 million kilometers. In this regard, the research on the relationship between steel quality and bearing life has achieved remarkable results, and the purity of steel is the primary factor affecting the life of bearing steel. [0003] It has been more than 40 years in my country to produce high-carbon chromium bearing steel by refining outside the furnace. With the improvement of equipment and technology level, the purity of steel ...

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Problems solved by technology

[0004] The existing patent ZL 01132236.5 is an out-of-furnace refining production method of ultra-pure high-carbon chromium bearing steel; Out-of-furnace refining production method of D-type inclusions in chromium bearing steel, patent ZL 200710048395.2 method for producing low-oxygen high-carbon chromium bearing steel by converter continuous casting process and patent ZL 201010179893.2 out-of-furnace refining production method of high-carbon chromium bearing steel , high-carbon chromium bearing steel is produced by refining outside the furnace, but the purity level of the steel produced is not high, such as the total oxygen content T.O is only 7ppm ~ 15ppm, brittle DS inclusion particles ≤ 27μm; its production process is not perfect , if there is no key equipment that has a greater impact on quality, such as molten iron pretreatment, RS slag removal technology, RH vacuum degassing, etc.; process control is not perfect, such as the sulfur content of raw materials before entering the converter, the carbon content at the end of the converter, etc. have a greater impact on quality Large key parameters are not involved or the level of control is not high

[0005] The existing patent ZL 200510027394.0 is a smelting production method of extremely pure high-carbon chromium bearing steel, which is produced by a dual process of vacuum induction furnace and vacuum consumable furnace. This process is completely different from the production method of refining outside the furnace, and the production efficiency is low and High production cost, high energy consumption, not suitable for mass production

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