調質圧延におけるロール表面テクスチャーの転写

Abstract

The surface texture of thin steel sheet provides considerable effect on sheet press formability and image clarity after coating for automotive body parts and beverage can uses. However, the transcription mechanism of surface texture, such as surface roughness, from roll onto deformed sheet has not been clarified, because of the complexity of elastic–plastic deformation of the rolled sheet in temper rolling. Temper rolling experiments for as-annealed low- and high-carbon steel sheets have been conducted in the reduction range from 1.0 to 8.0% using a laboratory-scale rolling mill. Bright rolls, shot dull rolls and electric-discharged rolls were employed. Dry, soluble oil and mineral oil were applied as lubrication states in the rolling experiments. The surface microstructures of temper-rolled sheets were observed. Three-dimensional (3D) surface textures of the rolled sheets were measured, in terms of 3D mean roughness (SRa), 3D maximum profile peak height (SRp), 3D minimum profile valley depth (SRv) and 3D material ratio (Rmr) curves. The probability densities of surface roughness were analyzed from the Rmr curves for both rolls and deformed sheets. From the results, the transcription of roll surface textures onto the temper-rolled sheets was discussed.