Aluminium has very big avidity to oxygen, and as the reductor of steel-making, it has obtained widespread use.
Aluminium is used for the deoxidation and the crystal grain thinning of steel, adjusts the austenite crystal growth, thereby improves the plasticity and the toughness of steel.Known multiple steel will be handled through further adding aluminium, can reduce the possibility of steel ingot or steel billet generation subsurface bubble with aluminium, and the crystallization refinement can improve steel impelling strength longitudinally.Because low, the easy scaling loss of light specific gravity, fusing point of aluminium is received lowly with aluminium deoxidation, effective rate of utilization is also low, and in air and under the effect of the oxygen in the slag, nearly 70~90% aluminium is oxidized, thereby remaining aluminium had both hanged down also unstable in the steel.
Magnesium is the optimum feed stock of a kind of reductor, particularly liquid steel desulphurization.But because magnesium has very high vapour pressure, very easily vaporize and burn, so it is all very difficult to be directly used in the deoxidation and the desulfurization of steel-making.
Aluminium and magnesium are ideal deoxidation and the sweetening agents of steel-making, and when particularly aluminium and magnesium being used jointly, they have the obvious synergistic effect, thereby good deoxidation, sweetening effectiveness are arranged.In order in STEELMAKING PRODUCTION, to be able to sufficient utilization, aluminium and magnesium are added iron and silicon and/or manganese and/or barium etc. cast alloy, improve proportion, fusing point, thereby can in steel-making, directly use, can improve the rate of recovery again.
The object of the present invention is to provide a kind of alloy that makes deoxidation of molten steel and desulfurization that has.
The Chemical Composition of this alloy (weight %) is: Al2O~80%, Mg2~60% is selected from SiO~30%, BaO~10%, SrO~5%, CaO~5%, one or more alloying elements in MnO~30% and the Fe of surplus.
The manufacture method of described Al-Mg-Fe alloy is: earlier Al, Mg and/or Si and/or Mn and/or Ba and/or Sr and/or Ca are put into smelting furnace and be smelted into master alloy, add Fe again, cast alloy block after the fusing.
During use described Al-Mg-Fe alloy is directly dropped in the molten steel.
Aluminium and magnesium are ideal deoxidation and the sweetening agents of steel-making, but make it be difficult to directly join in the molten steel because fusing point is low, inflammable, proportion is little etc., influence its application in practice.The present invention makes alloy for addressing this problem with magnalium iron, can increase proportion like this, makes it sink to the molten steel deep, is convenient to the use of producing simultaneously again.Silicon and/or manganese contained in this alloy can form the lower inclusion of fusing point with the oxide compound of aluminium, iron, help its come-up in molten steel, thereby have improved the degree of cleaning of molten steel.In addition, magnesium and iron can not form alloy, but ferro-aluminum can form alloy, and the present invention makes alloy together with aluminium, magnesium, iron for this reason.
Magnesium is known strong deoxidization desulfuration element, but because the proportion of magnesium is little, it can't be added in the molten bath with ordinary method, again because of its high boiling point and active chemical property, so very easily burn on the top of the slag.Promptly use mechanical means that it is added in the molten bath by force, also can make the molten bath that splash takes place, do not have the effect of deoxidization desulfuration thereby the safety that not only jeopardizes operator also makes a large amount of burnings of magnesium because of the gasification of magnesium.
Al-Mg-Fe alloy provided by the invention makes magnesium be in the alloy attitude and can prevent that magnesium is by in the air and the oxygen burning in the slag because its proportion can be added in the molten bath than die.Because the shock absorption of silicon, barium, strontium, calcium and manganese has suppressed the dissolving and the speed of response of magnesium, thereby there are sulphur and oxygen in adequate time and the molten steel to react.And owing to suppressed the speed of response of magnesium, thus eliminated the risk of splash, can also strengthen deoxidation and sweetening power simultaneously and reach the form of further improving inclusion.Though aluminium among the present invention and magnesium all have very strong avidity with oxygen, sulphur, the two makes alloy together then the stronger deoxidation and the effect of desulfurization.Therefore, the present invention not only can improve steel product quality but also can reduce steel-making cost, increases economic efficiency.
Use the form and the structure of the inclusion in the steel of alloy smelting of the present invention, find through scanning electron microscope analysis: the oxide inclusion of iron, magnesium mostly is strip, and its sulfide inclusion mostly is spherical, and disperse distributes, and seldom sees chain Al
2O
3Inclusion.Hard in the middle of these inclusiones that alloy of the present invention forms, the edge has elasticity, can reduce stress in System on Rolling Steel.
Magnesium can be removed sulphur and oxygen in the steel, purifies metal.In simultaneous test, use sweetening agent (as lime, fluorite etc.) to carry out desulfurization, sulphur is still about 0.05%; And it is use Al-Mg-Fe alloy desulfurization of the present invention, the sulphur in the steel further to take off, and all better in aspect effects such as quality, economy, environmental protection and safety to 0.003%.
Embodiment:
Use the component content (weight %) of alloy of the present invention to be:
Al40%, Mg5%, Si8%, Mn20%, surplus is Fe.
Its manufacture method is: earlier Al, Mg, Si and Mn are put into main frequency furnace and melt, add Fe then, the Al-Mg-Fe alloy piece is cast in fusing at last.
In 120 tons of converters, smelt 70 with above-mentioned Al-Mg-Fe alloy
#Carry out deoxidization desulfuration during steel, a ton steel adds 1 kilogram of this alloy, and mechanical property all is better than GB in the steel after tested, as following table:
The technical indicator (15 of table 1 embodiment
#)
Standard | Yield-point (kg/ mm
2) be not less than
| Tensile strength (kg/mm
2) be not less than
| Elongation δ % is not less than | Section is received string shrinkage % and is not less than | ????[S] ????% | ???[O] ???ppm |
GB | ????420 | ????715 | ????9 | ????30 | ?0.005 | ????50 |
This product | ????460 | ????823 | ????11 | ????36 | ?0.03 | ????25 |