# Influence of Roll Diameter on Material Deformation and Properties during Wire Flat Rolling
###### Abstract  
The influence of roll diameter on the strain distribution, shape change, contact pressure, and damage value of a workpiece was investigated during wire flat rolling to control the material properties of the flattened wire. The flattened wires fabricated by the four different rolls were compared using finite element analysis. The strain inhomogeneity of the flat-rolled wire increased with the roll diameter; thus, the macroscopic shear bands were strengthened as the roll diameter increased during wire flat rolling. The contact width and lateral spreading of the flattened wire increased with the roll diameter; therefore, the reduction in area decreased with the roll diameter. The contour of the normal contact pressure on the wire surface exhibited a similar pattern regardless of the roll diameter. The contact pressure showed higher values at the entry, edge, and exit zones in the contact area. The distribution of the damage value varied with the roll diameter. The free surface region tended to have the peak damage value during the process; however, the center region exhibited the maximum damage value with the roll diameter. From the perspective of the damage value, the optimum roll diameter was in existence during wire flat rolling. The underlying cause of the different strain distributions, shape changes, and damage values of the flat-rolled wire was the different contact lengths originating from the different roll diameters during wire flat rolling. roll diameter; wire flat rolling; strain distribution; contact pressure; damage value +
Footnote †: journal: Applied Sciences  
**Citation:** [PERSON]; [PERSON], [PERSON]; [PERSON]. Influence of Roll Diameter on Material Deformation and Properties during Wire Flat Rolling. high ductility as well as high strength [6; 7]; this is highly advantageous from the manufacturer's perspective. However, these studies revealed that strain inhomogeneity occurred in the flat-rolled wire, indicating the necessity of heat treatments during the manufacturing process to reduce the strain inhomogeneity of the flattened wire. This is not the preferred direction for manufacturing processes in metal forming and related industries [8; 9]. Therefore, considerable efforts have been expended to predict and decrease the strain inhomogeneity of flattened wires during the process using experimental and numerical approaches. It has been revealed that the strain distribution of the flat-rolled wire depends significantly on the working conditions, such as lubrication, reduction ratio, roll diameter (\(D\)), and rolling speed [1; 5; 10; 11; 12]. According to the previous studies, the homogeneity of the mechanical properties increased with a decreasing friction coefficient and roll diameter, and with an increasing reduction ratio. It was reported that the influence of the rolling speed on strain inhomogeneity is insignificant. Although the roll diameter is a working condition that can be changed easily in industrial fields, only a few investigations have focused on the effect of the roll diameter on the wire quality during wire flat rolling. For example, [PERSON] [5] reported that the strain homogeneity of the flat-rolled wire increased with decreasing roll diameter; however, only the results were reported, and the detailed underlying mechanism was not revealed in the study. Meanwhile, the shape control of the product is crucial in metal forming processes. In particular, the fabrication of the desired product shape is more important in the rolling process because direct control of the product shape is impossible during the process originating from the spreading effect at the free surface of the workpiece [13; 14; 15; 16; 17]. During wire flat rolling, spreading occurs more easily compared with plate or strip flat rolling because of the initial shape of the wire with a high width to height ratio [18; 19].