The bright steel round bars are drawn through dies of the required shape. The raw material is chosen depending on the shape to be drawn. This increases the yield strength and tensile strength. This also eliminates a number of surface imperfections caused due to the rolling process.
The black bars are turned to the desired sizes. This process eliminates all surface imperfections. But internal imperfections if any are exposed. This process does not increase the tensile strength of the bars
The grinding process is used to narrow the tolerances and improve the surface finishes of the above two processes
The polishing process improves the surface finish of the bars
Cold Rolling is typically used to produce complex shapes.