The key factor affecting the quality of bearing steel composition and inclusions and its control

 Oxygen impact on the quality of bearing steel and its control & # 61550; Inclusions in bearing steel and its control & # 61550; The control of the residual aluminum bearing steel & # 61550; The control of the residual titanium bearing steel & # 61550; Sulfur content & # 61550; Carbide defects 1 oxygen in steel impact on the quality of bearing steel and its control in steel wT. O = 10×10 - 4% of the fatigue life of bearing steel than wT. O = 40×10 - 4% increase 10 times. wT。 O = 5×10 - The fatigue life of 4% wT. O = 40×10 - 4% 30 times. Bearing steel production is the key to DNA. That should be paid attention to the problems in the process of smelting & # 61550; Early steel liquid achieve low oxidation and low temperature;  Strengthen the steel water deoxidization, at the beginning of the  Using diffusion deoxidation of SiC and Al powder;  Refining, in the middle of the oxygen content in steel is reduced, decreases in the Al adopt the method of feeding Al line add Al;  Select the appropriate refining slag system;  To prevent the secondary oxidation;  Reasonable argon blowing system;  Control the appropriate amount of the residual aluminum.  To ensure enough vacuum and vacuum time. 2 inclusions in bearing steel and its control & # 61550; The change of number of non-metallic inclusions in steel and components & # 61550; The sulfide inclusion in steel impact on the quality of bearing steel & # 61550; Process parameters on the influence of the content of inclusions in the steel & # 61550; Inclusion in the casting process control of non-metallic inclusions in steel quantity and composition change & # 61550; Greater than 5 microns of inclusions in steel in the vacuum after the most has been removed. Inclusion quantity one-third less than they did before the vacuum;  15 min after the SKF study found: the steel inclusion is mainly composed of Al2O3 and Al2O3 & # 8226; SiO2• MnO, from electric arc furnace tapping pre deoxidizing products; Before the vacuum - — 氧化铝• CaO inclusions, Al2O3 and ferroalloy Ca - The calcium in Si reaction products; After vacuum - — Inclusion of Al2O3 & # 8226; CaO often wrapped in a layer of the MgS, Mg from the refractory material under vacuum, and Al2O3 generated Al2O3 & # 8226; MgO。 The sulfide inclusion in steel impact on the quality of bearing steel & # 61550; Good & # 61550; Harmful & # 61550; Little effect on the fatigue life of steel process parameters on the influence of the content of inclusions in the steel & # 61550; Electric furnace tapping temperature & # 61550; Mixing time & # 61550; Aluminium deoxidizing process Ascometal company believes, for bearing steel refining, should focus on: choose basic refractories ladle lining; Maximize the removal of slag; As soon as possible of refining slag formation is very low oxygen potential; Control gas stirring, inclusion floatation. Inclusion in the casting process control & # 61550; Die casting - — Focus on avoiding the ladle of molten steel flow between the mold and secondary oxidation; The effect of molten steel and refractory material is minimized; Ladle slag is minimized the involvement of the agent or casting slag heat preservation, heat preservation;  Continuous casting - — Detection of ladle slag quantity; Blowing argon protection, prevent secondary oxidation; Quality selection of refractory material. The control of the residual aluminum 3 bearing steel & # 61550; Metal aluminium and AlN soluble in acid, with [ Al] S said. Final deoxidization with Al is to obtain low oxygen content of molten steel and ensure appropriate [in steel Al] S。 ( Al] S high - — Protection condition not easy secondary oxidation increased Al2O3 inclusions; ( Al] S low - — Si secondary oxidation and molten steel temperature lower dissolved oxygen precipitation, SiO2 which was produced from high bulky vitreous silicate inclusions. If you want to make steel grain refinement, to obtain high strength toughness, residual aluminum can be high. Residual aluminum for carburizing bearing steel, the need to control high; For high carbon steel bearing control requirements is not too high. 4 the control of the residual titanium bearing steel & # 61550; Harmful, titanium for high carbon chromium bearing steel in steel with Ti ( C, N) , TiC, TiN, exist in hard water caltrop. Under the same size, harm is greater than the Al2O3;  Practice has proved that the wTi x 10-50 4%, significantly lower bearing fatigue life. In the production of electric arc furnace, high N - — More strictly control the residual Ti;  SKF3 wTi 0 or less prescribed standards abroad. 003%;  The mass production of bearing steel is not higher than 50 x 10 - titanium content Almost no effect of 4%, on fatigue life, higher than this value, TiN and oxide, or clusters of TiN itself between effect, lead to an increased incidence of microcrack, worsening fatigue strength;  The high frequency of company development featuring low titanium SUJ2KRF steel wTi 18 x 10 - or less 4%, 2 times higher than that of ordinary bearing steel;  Japan's sumitomo corporation of different titanium and oxygen content of steel pipe test proves that the low oxygen and low titanium is helpful to improve the service life of bearing. Sulfur content 5 & # 61550; Many people think that sulfur content will not affect the bearing life, even can reduce the harmful effect of oxide. But with the improvement of pure steel, oxide inclusion content decreased, and the harmful effect of sulphide gradually show the & # 61550; A Japanese famous miniature bearing companies require sulfur content is not higher than 0. 003% The Swedish SKF - — 0. 015% Baosteel - — 0. 008% 6 carbide defects in steel & # 61550; Carbide defects including liquid chromatography, banded carbide carbide and carbide network, the harm of inclusions;  Main origin steel carbide defects segregation in solidification process, control and reduce the solidification segregation is a key link in the process of control and reduction of carbide defects;  The reasonable heating, rolling and heat treatment process can further improve the carbide structure and morphology, reduce the harm.