Research On The Effect Of Steel Wires In Waste Tires On The Structure And Performance Of Gray Cast Iron Brake Discs

In this paper,the high-performance gray cast iron brake disc was made by using scrap tire inner steel wire instead of pig iron and common scrap steel,use wrought coal type 90 carburizing agent for carburizing treatment,use 75 ferrosilicon inoculant for one-time inoculation,use the silicon-barium-calcium-aluminium inoculation for secondary inoculation,and add Cr,Cu and other alloying elements to strengthen the structure.in the same casting process,the amount of steel wire in different waste tires was compared and studied by comparison: 30%,40%,50%,60%,70%,80% room temperature structure,number of eutectic clusters,mechanical properties,tensile fracture morphology Influence of wear resistance and cycle life.preparation of ash with chemical composition 3.2%-3.4% C,1.7%-1.9% Si,0.7%-0.8% Mn,0.04%-0.08% S,?0.1% P,0.2%-0.25% Cr,?0.3% Cu Cast iron brake disc and?30 single-cast test rod,then the metallographic structure,hardness,tensile strength,number of eutectic clusters,tensile fracture morphology,wear resistance,and cycle life of the test piece were analyzed.the result shows:With the increase of steel wire content from 30% to 80%,The content of type A graphite in the room temperature structure of gray cast iron brake discs increased from 97.6% to99.2%.The average length of graphite is reduced from 0.2347 mm to 0.1071 mm,the distribution of graphite is gradually uniform,the curvature of graphite increases,and large type A graphite gradually decreases.The content of pearlite gradually increased from 96.8% to99.2%,and the content of ferrite decreased from 2.7% to 0.5%.The distance between pearlite sheets decreased from 2.14 mm to 0.82mm(magnified by 500 times),the distribution of pearlite was gradually uniform,the distance between pearlite sheets was refined,and the grade of the distance between pearlite sheets changed from grade 4 to grade 2.The hardness of the gray cast iron brake disc increased from 191 HB to 209 HB,the overall growth value is18 HB,the tensile strength of gray cast iron brake discs increased from 231 MPa to 275 MPa,and the overall increase was 44 MPa.The test tensile strength and hardness are within the range specified in the standard EN-GJL-200.The fracture mechanism is composed of cleavage fracture and intergranular fracture.The dissociation surface is mainly distributed in a fluvial pattern,the size of the dissociation platform is gradually reduced,the bending tearing edge is gradually increased,the tearing area is further expanded,the proportion of dissociation fracture in the compound mechanism of cleavage fracture and intergranular fracture is reduced,the effect of splitting the matrix by coarse graphite is reduced.In the friction experiment,when the proportion of steel wire in waste tire is 70% and 80%,the grey cast iron brake disc has better friction performance.When the steel wire content in the waste tire is 80%,the gray cast iron brake disc has a good cycle life,It has exceeded the test performance of 95 cycle tests and380 times of brake stops of the international OE disk in the standard EN-GJL-200.Compared with the common scrap steel and pig iron and other raw materials,the grey cast iron brake disc produced by the scrap steel wire in the tire has better metallographic structure and mechanical properties.