On the correlation between roping, texture, and morphology of aluminium alloy sheets

Roping is a troublesome surface defect of aluminium alloy sheets that hinders their application in the automobile industry. When the aluminium alloy sheets are subjected to tension, the texture components of various distributions will lead to non-uniform morphology and thus initiate roping. In the current paper, the correlation of roping defect with texture and surface morphology is probed by experiments and crystal plasticity simulation in four aluminium alloy sheets. Depending on the extension length of roping lines along the rolling direction, short and long roping are identified from the tested aluminium alloy sheets. With crystal plasticity simulation, texture variances for different roping degrees are comparatively analysed. The short roping is induced by short clusters of individual hard components, while the long roping is initiated by the long bands where different hard components are mixed. The experimental and simulation results also indicate that roping does not result from specific textures in the aluminium alloy sheets, and the alternative spatial aggregation of soft and hard texture components plays a predominant role in roping development. A roping intensity index RI is also proposed to quantitatively grade roping intensity and show excellent accuracy and robustness in practice.