Fine Grain Strengthening Improves The Microstructure And Mechanical Properties Of Manganese Metal

Due to the low cost and high purity,the electro silicothermic metal manganese has been widely used in the iron and steel industry.However,it is hard and brittle,the powder ratio is higher than 20%in crush and transportation process.Although the powder of metal manganese can be recycled,the smelting cost inevitably increased.Accordingly,how to improve the mechanical properties of metal manganese has become the focus attention of ferromanganese enterprises.Grain refinement strengthening as an effective method can simultaneously achieve the improvement of strength,hardness,plasticity and toughness.Therefore,based on the microscopic perspective of solid/liquid interface,this paper first studied the effect of nucleation process on the microstructure of metal manganese by pouring solidification experiment and mainly discussed the mechanism of grain refinement of metal manganese from the point of view of nucleation.Secondly,the effect of microstructure on mechanical properties of metal manganese was studied by pouring experiment and the relationship between grain size and mechanical properties was established.Finally,refining the micro structure of metal manganese by metamorphic treatment and vibration treatment.The main conclusions are as follows:(1)The average grain size of metal manganese decreased with the decrease of the critical nucleation radius.When the criticual nucleation radius gradually decreased from 167.9nm to 64.3nm,the average grain size gradually decreased from 69.3?m to 53.6?m.Finally,the following exponential relationship between critical nucleation radius and average grain size of metal manganese was obtained:r = 69.15 · exp {-exp[0.05(r*-37.16)]},R~2 = 0.9460(2)The comprehensive strength of metal manganese increased with the decrease of the average grain size.When the average grain size decreased from 69.3?m to 53.6?m,the comprehensive strength of metal manganese was gradually increased from 73.2 to 97.0.Finally,the following Hall-Petch relationship between average grain size and comprehensive strength of metal manganese was obtained:?=1755.34d-1/2-137.27,R~2=0.9346(3)Cr metamorphic treatment can effectively refinedthe microstructure of metal manganese.When the addition of Cr was 2.0%and the metamorphic temperature was 1350?,the average grain size of metal manganese was only 37.5?m.(4)Vibration treatment can effectively refinedthe microstructure of metal manganese.On the basis of metamorphic treatment,the average grain size of metal manganese would respectively reduce to 42.6?m and 44.2?m after further treatment by mechanical vibration and ultrasonic vibration.