Study On Heat Treatment Process Of New Twining Inducec Plasticity Steel

Bolt support is one of the main support methods in coal mining.High strength and high elongation have always been the research focus of roadway support materials.However,the current performance of steel for bolts can no longer meet the requirements of deep mining.Twinning Induced Plasticity(TWIP)steel has high elongation,high strength and high absorption energy.TWIP steel is used as the bolt Materials,on the premise of reducing the weight of supporting materials,reducing the construction period,and reducing the construction cost.It can largely guarantee the safety of deep coal mining,maintain the stability of the rock mass,reduce the displacement and deformation of the roadway,and maintain the integrity of the roadway space.This paper takes Fe-18Mn-2Al-0.6C-0.5Si TWIP steel as the research object,and explores the effect of different annealing temperature,holding time and cooling method on the microstructure and properties of TWIP steel.As the annealing temperature increases,the holding time increases,the grain size increases,the twin size increases,and the number increases.When the annealing temperature is too high,the grain size of TWIP steel is too large,and the difference in grain size will increase.Due to the difference in grain size,the deformation of each grain is uneven,and stress concentration will occur inside the grain,making micro cracks in the steel The rapid expansion and extension in the middle makes each grain break before the maximum deformation it can withstand,delaying the TWIP effect.When the annealing water cooling,as the annealing temperature increases,the tensile strength gradually decreases,and the elongation after fracture first increases and then decreases.When the annealing temperature is 1000℃,the elongation is the highest,73.13%,and the annealing temperature is 850℃,the strength is the highest,977.6 MPa;when annealing at 1000℃,with the increase of the holding time,the tensile strength gradually decreases,and the extension after breaking The growth rate first increases and then decreases.When the holding time is 10 min,the strength is the highest,which is 896.59 MPa,and when the holding time is 20 min,the elongation is the highest,which is 73.13%.When the annealing method is air-cooled,with the increase of annealing temperature,the tensile strength gradually decreases,and the elongation after fracture first increases and then decreases.When the annealing temperature is 850℃,the strength is the highest,968.88 MPa,when the annealing temperature is 900℃,the elongation is the highest,78.8%;when annealing at 1000℃,with the increase of the holding time,the tensile strength gradually decreases,and the extension after breaking The growth rate first decreases and then increases.When the holding time is 10 min,the strength is the highest at 888.36 MPa,the elongation is the highest at 71.87%,and the comprehensive performance is the best.Since the cooling rate of water cooling is greater than that of air cooling,with the increase of cooling rate,the grains do not have enough time to grow,and the size of water cooled grains is significantly smaller than that of air cooling,which plays the role of fine crystal strengthening,making the tensile strength of water cooling and the elongation is greater than air cooling.