Preparation Of Barium Bearing Silicon-manganese Alloy And Research On Its Pulverization Mechanism

The reserves of manganese ore resources in China is very rich,while in the whole Country,it has the characteristics of uneven distribution,low grade of manganese ore and high impurity content.Besides,the competitive power of the development of manganese industry is restricted due to the lack of scientific planning and guidance.Therefore,the development of high value-added barium-containing siliconmanganese alloy is of great significance for rational utilization of manganese resources and adjustment of industrial structure.What matters is that high quality intermediate alloy is badly needed to improve the quality of steel along with China's iron and steel industry overcapacity adjustment period,which not only realizes the structural use of low manganese ore resources,but also increases the added value of alloy products.Barium bearing siliconmanganese alloy is a new master alloy which can be used as deoxidation and desulfurization of steel,and at the same time,it can also provide the alloying elements to refine grain and improve the anisotropy of steel.However,there is a serious loss of elements in the process of alloy smelting which reduces the yield of the metal.The alloy products apt to appear the phenomenon of disintegration which cut down its practical applicatioin value.Therefore,in this paper,the research area is to reduce the loss of alloy elements and avoid alloy pulverization.The desintegration mechanism of alloy is deeply explained in mang respects.The following results are obtained through a series of studies:(1)The melting of alloy feeding process: first to join the pre mixing with slag;Then add the silicon manganese alloy and titanium iron into slag;as the melt heats up to complete melting,silicon manganese alloy or aluminum scraps are put in the melt rapidly to avoid the burning loss of alloying elements.Last but not least,cast after the reaction of the melt is under control properly.(2)The addition of Al or Ti plays a positive effect on the powdering alloy.The experimental results show that the barium containing Si-rich alloy mixed with 1~3% titanium or 2~10% aluminum can avoid the formation of crack phase Fe Si2 and deliquescence phase Ba Si2 to play a “passive” role in the un-powdered alloy;and the evaluation of titanium addition to the alloy may achieve the best effect when its dosage is 2%.(3)By the comparative analysis of DSC-TG: the powdered alloy begins to decompose at about 210?,and a single stage of the weight loss process is at 253? to the fastest.Non powdering alloy is decomposed at about 141?,and the weight loss process is divided into three stages,the maximum weight loss rate of each stage are at 161?,481.2? and 705.2?.(4)The analysis of macro morphology of the alloy samples and apparent quality evaluation show that: the quality of the alloy is poor because the slow cooling rate leads to the gravity segregation of alloy(silicon segregation)and internal stress,and its resistance index was above 20.However,once the barium containing Si-rich alloy is placed under the condition of water cooling,it may cause the shrinkage of the alloy or the formation of shrinkage cavity,and even the severe hot cracking phenomenon occurs in the later stage.(5)The phase of Silicon-manganese alloy doped with barium has been analyzed by SEM,EDS and XRD.The results show that the alloy phase-Al4 Ba,Ba Al2Si2,Al Fe3,?-Mn,Ti C,Ti Fe Si2 etc.exist in alloy;It is proved that the phase transformation and thermal mismatch of Fe Si2 are the fundamental causes of crack initiation because Fe Si2 phase in powdered alloy is transformed to Ti Fe Si2 or Al Fe3 phase in un-powdered alloy.And the deliquescence phase Ba Si2 exists in the form of Al4 Ba and Ba Al2Si2 which represents that Ba Si2 is the main reason of the powdering Silicon-manganese alloy doped with barium deliquescence.