A general kinematically admissible velocity field applicable to forging of a rectangular strip of a incompressible material is presented. Generalized shape of any dead zone, if assumed, can be obtained in terms of process parameters from this velocity field. Two different upper bound solutions for average forging pressure are obtained from simple velocity fields which are special cases of proposed general velocity field. Numerical results of the solutions show improvement over previous upper bound solutions published in literature over a certain range of process parameters.

Quenched and tempered plate steel is capable of modified cup-and-cone fractures involving one or more longitudinal cracks “parallel” to the flat plate surfaces. The occurrence was verified by tensile testing of three steels at a variety of temperatures. Electron fractography revealed that quasi-cleavage, shear lips, tearing, and normal rupture were active, being identified by modified river patterns and by elongated and equiaxed dimples resulting from the coalescence of microvoids. The brittle longitudinal cracks are formed shortly before final rupture. Application of the Bridgman plasticity solution for necked tensile specimens shows that the split, layered, fracture occurs under unique stress conditions.

A total of 31 stress-rupture data sets for 28 different nickel-base alloys, including 1153 individual test results, have been treated by graphical methods and computer programs to allow determinations of the relative abilities of Larson-Miller, Manson-Haferd, Sherby-Dorn, Goldhoff-Sherby, Manson-Succop, Conrad and Korchynsky parameters to correlate and extrapolate data. For the correlation of all data the Goldhoff-Sherby and Manson-Haferd methods are attractive, while for extrapolation to longer times some superiority of the Manson-Haferd and Manson-Succop parameters is demonstrated. Overall use of a third order polynomial approximation to Manson-Haferd master curves is recommended, as is the avoidance of external extrapolation. Results are primarily based on modified and original computer programs and standard statistical treatments of data.

A type of tensile fracture topography encountered fairly often in certain temperature ranges with specimens from forgings, billets, rod, and bar of quenched and tempered steel, is the “star” or “rosette.” Having available several steels which had been shown to be capable of exhibiting the rosette, star, fracture, tensile testing was done to establish the temperature ranges for which this fracture configuration was applicable. Explanations of the fracture, and determinations of the fracture modes, were sought through experimentation involving metallography and the electron microscope, and by application of continuum mathematical plasticity-fracture theory.

Rolling-direction tensile specimens of 0.31 C quenched and tempered alloy plate steel displayed cup-and-cone, split-layered, neck-and-split, and square-break fracture configurations over distinct temperature ranges as testing temperature was lowered from 300 to −320 F. Formation of the neck-and-split configuration was investigated in terms of stress state, temperature, void formation, and anisotropy. Electron fractography identified quasicleavage as the fracture mode of the initially occurring longitudinal split. The brittle fracture phenomenon resulting in the neck-and-split fracture of plate specimens occurs under a unique combination of conditions.