The effect of controlled cooling process after hot rolling on the microstructure and mechanical properties of 75Cr1 steel after spheroidizing annealing was invesgated to meet the requirements of high strength,good toughness,corrosion resistance,high hardenability and thermal stability for saw blade steel.Electron probe microanalyzer(EPMA)and transmission electron mi-croscopy(TEM)were utilized to characterize the microstructure of the experimental steel after hot rolling and spheroidizing an-nealing.The results revealed that different controlled cooling processes after rolling produced three types microstructure of hot rolled experimental plates with lamellar pearlite,pearlite+ferrite and pearlite+bainite microstructure.When the microstructure of the experimental plate after hot rolling was lamellar pearlite,the cementite particles were evenly distributed after spheroidiza-tion annealing,and the yield strength and tensile strength were 473 MPa and 556 MPa,respectively.When there was ferrite in the hot rolling microstructure,the spheroidized cementite particles aggregated,the grain size increased and the strength of the plates decreased.When the microstructure of the experimental plate after hot rolling was bainite,the diffusion distance of carbon atoms in the spheroidizing process was shortened,and a good spheroidized microstructure was obtained.The yield strength and tensile strength after spheroidization annealing were 553 MPa and 638 MPa,respectively.A comparative analysis was conducted on the spheroidization annealing effects of plates with different hot rolled microstructures.It was observed that controlling the fi-nal cooling temperature at about 510 ℃ during hot rolling resulted in a bainite microstructure whih facilitated obtaining a favora-ble spheroidized annealing microstructure compared to lamellar pearlite or ferrite+pearlite microstructures.
75Cr1 saw blabe steelhot rolling processspheroidal annealingcementitepearlitemechanical properties
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