关键词: 纯铁, 表面粗糙度, 润滑, 残余应力, 金相组织, 显微硬度

Abstract: In order to improve the surface quality of pure iron materials during the finishing turning，some experi-ments were carried out at the same cutting parameters under such four cooling/lubrication conditions as dry cutting，water-based cooling，rapeseed oil lubrication and minimum quantity lubrication (MQL)，and the influence mecha-nisms of cooling/lubrication conditions on the surface integrity of the pure iron workpiece were analyzed． The re-sults indicate that (1) as compared with the dry cutting and the water-based cooling，the MQL and the rapeseed oil lubrication are more advantageous to the improvement of the surface roughness of the workpiece; (2) the surface microhardness varies in the same trend under different cooling/lubrication conditions，and the depth of hardened layer is about 60 ～70μm; (3) the surface grains show severe tensile and distorted plastic deformation，and the dry cutting results in the deepest deformation while the water-based cooling results in the shallowest deformation; and (4) the surface residual stresses in the tangential and the axial directions are both tensile and insensitive to coo-ling/lubrication conditions，and the tangential stress is larger than the axial one． These experimental results are of great significance for selecting suitable cooling/lubrication conditions to improve the surface integrity of pure iron materials during the finish turning．

Key words: pure iron, surface roughness, lubrication, residual stress, metallographic structure, microhardness