Abstract: Focusing on the strict requirements for blade sharpness, hardness and wear resistance of chaff cutter blade, the balance between hardness and toughness of 65Mn steel was achieved through salt bath quenching with different heating temperatures and tempering. The microstructure, hardness, friction and wear resistance of the steel were studied systematically. The results show that when austenitizing at 840 ℃, the lath martensite of the 65Mn steel after quenching is smaller, together with clear acicular martensite. After tempering, the carbide in tempered martensite precipitates at the lath martensite interface, and its distribution is more uniform combined with smaller particle in the martensite matrix. The hardness of the steel after salt bath quenching at 840 ℃ and tempering is the highest, which is 58.04 and 53.50 HRC, respectively, combined with no excessively loss of the wear resistance for the 65Mn steel, meeting the application requirements of agricultural machinery materials. As a consequence, salt bath quenching at 840 ℃ and tempering is the optimal heat treatment process.

Key words: 65Mn steel, heat treatment, microstructure, friction and wear, mechanical properties, grass cutter blades