Microscopic Examination of Primary Shear Zone in High Speed Machining of Hardened High Strength Steel
The microstructure observation and microhardness measurement were performed on the adiabatic shear bands in primary shear zone in the serrated chips formed during high speed machining of two tempering hardness of hardened high strength steel under different cutting speeds by optical microscope, SEM, TEM and microhardness tester. The investigation results show that two types of adiabatic shear bands are formed as cutting speed increases. One is deformed band with heavy elongated microstructures generated under lower cutting speed, another is transformed band with fine grains under higher cutting speed. The increase of the cutting speed little influences on the microhardness in the transformed bands, and the microhardness in deformed band results from strain hardening, whereas transformation hardening leads to very high microhardness in transformed band.
Zhengyi Jiang and Chunliang Zhang
C. Z. Duan et al., "Microscopic Examination of Primary Shear Zone in High Speed Machining of Hardened High Strength Steel", Advanced Materials Research, Vols. 97-101, pp. 1887-1890, 2010