| High carbon Cr-Fe alloy is one of the most important raw materials for stainless steel production.As far,the production of high carbon Cr-Fe mainly uses the relatively low cost chromium ore powder to turn into spherical ore by "pelletizing process",and then smelts in the ore-heating furnace by "three-electrode method" smelting system.Slagging is a very important process in high carbon Cr-Fe smelting.The composition of slag determines the melting point temperature of slag,the temperature of slag determines the temperature of molten iron,and the temperature of molten iron determines the degree of reduction of Cr,Si,Fe and other beneficial elements.At present,when most enterprises actually produce Cr-Fe alloy,if they want to analyze the composition of molten alloy,a small amount of sample must be taken out after the furnace,after a series of physical and chemical analysis and detection steps,accurate composition can be finally obtained.These steps are very cumbersome,and need a lot of time,also need to consume a certain amount of manpower and material resources,and the drawback of this technical method is that of difficulty to adjust and control the smelting process in real time.Is there a method in which the composition of the slag and the composition of the alloy liquid can be obtained in real time and adjusted according to the composition of the slag,the slag temperature and the temperature of the molten iron?In this paper,the composition,slag temperature,hot metal temperature and Cr,Si,Fe content in ferroalloy products were determined on the spot,the effects of composition and alkalinity on slag temperature were analyzed in detail,and the influence of slag composition and basicity on slag temperature was analyzed in detail.The relationship between the temperature of molten iron and the content of reduction products was established.The mathematical relationship between the composition of slag and slag temperature and the relationship between the temperature of hot metal and the content of reducing elements were established.The metallographic structure of high carbon Cr-Fe was observed.When the mass fraction of SiO2 in slag is less than 30%,the melting temperature of slag increases with the increase of SiO2 content,the viscosity of slag is greatly influenced by Al2O3,and the slag temperature decreases with the increase of Al2O3 content.When the content of Al2O3 is 23%,the slag temperature is the lowest The mathematical relationship between CaO,MgO and basicity and slag temperature is summarized by processing slag temperature data with 3σ principle.When the temperature of molten iron exceeds 1620℃,with the increase of temperature,the content of Cr increases at first and then decreases,and reaches the maximum at 1650℃,which is 63.8%.However,the mass fraction of Si reduced is generally less than 4%.In the range of 1620～1670℃,with the increase of molten iron temperature,the content of Si increases at first and then decreases,and reaches the maximum value of 3.4%at 1640℃.The metallographic structure of high carbon ferrochromium is mainly wrapped,mosaic and silkworm structure.The phase composition is mainly composed of intermediate carbide(Cr,Fe)7C3 and eutectic low carbon ferrite.The intermediate carbide(Cr,Fe)7C3 is a regular hexagonal bar with large grain size and complete crystal form.The displacement of carbon diffusing from the grain to the grain boundary is larger and the energy required for solid phase decarbonization is larger.Eutectic low-carbon ferrite is chrysanthemum-like,and there are fine grains,many grain boundaries.It is easy for carbon to be of diffusion,and the energy required for solid-phase decarbonization is relatively small.The metallographic structure of high carbon ferrochromium is closely related to its cooling rate.The core of high carbon chromium iron castings is finally cooled,and the eutectic low carbon ferrite content is less.At the edge of the casting block,the cooling rate is faster and the high carbon chromium iron eutectic low carbon ferrite is obviously increased. |
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