The Use of Model Materials in Predicting Forming Loads in Metalworking

The laws of perfect and approximate similarities in metal forming indicate that perfect similarity in deforming two different materials is practically impossible to achieve. Approximate similarity, however, is easy to obtain and proves to be very useful in predicting forming loads in extrusion and forging processes. Analysis of friction in model experiments shows how interface friction can be taken into account in model studies. Backward and forward extrusion loads are predicted from plasticine model experiments, and the results are compared with data for various steels. Using published experimenal data, the load-displacement curve in a closed-die forging has been predicted by means of model theory. The agreement between predicted and actual loads is well within useful engineering accuracy.</jats:p

Cold Extrusion of Unalloyed Titanium

Abstract The first known successful cold extrusion of titanium was accomplished at Battelle on a project for Wright Air Development Center. Working with commercially pure grades of titanium having 45,000 and 70,000-psi yield strengths, and employing a Battelle-developed fluoride-phosphate coating for titanium, billets 1½ in. diam were forward extruded to bars 1.16, 1.06, and 0.95 in. diam. These correspond to reductions of 40, 50, and 60 per cent. The fluoride-phosphate coating, in combination with a conventional oil-graphite-molybdenum disulphide lubricant, prevented seizing and galling and produced a smooth surface finish. The extruded bars exhibited as high as a 60 per cent increase in strength, yet adequate ductility (10 per cent in 1 in. minimum) was maintained.</jats:p