Abstract: A method for reducing the part-to-part cycle time of quick plastic forming and superplastic forming of a metallic sheet alloy into an automotive sheet metal component by locally modifying a die surface to control friction which militates against undesirable necking and thinning.

Abstract: A method is disclosed for stretching magnesium-containing aluminum alloy sheet stock into intricate shapes such as are required in automotive body panels. The sheet stock, at a temperature in the range of about 400° C. to about 510° C., is stretched under the pressure of a working gas into conformance with the surface of a forming tool. The sheet forming pressure is increased continually in a controlled manner from ambient pressure to a final forming level in the range of about 250 psi to about 500 psi or higher. A portion of the sheet can experience strain rates substantially higher than 10−3 sec−1 and the forming of the sheet can be completed within 12 minutes.

Abstract: A method is disclosed for stretching sheet blanks, especially superplastic sheets, by differential gas pressure into conformity with a female die surface without encountering excessive thinning or tearing of the sheet. The warmed SPF sheet is draped over a preformed surface to draw more of the sheet material into the die cavity before the edges of the sheet are fixedly clamped whereby the additional formable material is used in forming the product, thereby reducing thinning and tears.