Quasi-bulk deformation of the viscous medium and metal blank can be achieved when appropriate types of highly viscous semi-solid polymer, namely viscous medium, acts aspressure carrying medium. Excessive wall thickness reductionof thin-walled circular rings with corrugated meridians wasre strained effectively by this process. The mechanism of thisprocess is that the tangential adhesive force caused by highviscosity of viscous medium promotes the nearly synchronous material flow of viscous medium and ring-shaped blank.