Abstract: In hydroforming of hollow metal articles in a die, such as pressure-ram-forming procedures, a method of decreasing cycle time of the forming process, while ensuring acceptable product properties and avoiding failures, by modeling the process using finite element analysis to establish a pressure-time history that optimizes the forming operation and applies failure limits to selected variables such as minimum wall thickness or maximum strain rate, and transferring this pressure-time history to a computer controlling the forming process. Thermocouple and/or continuity sensors are incorporated into the die wall and connected to the computer so as to provide active feedback from the die to the control of the process.

Abstract: A method of fabricating an article from a blank of material (e.g., aluminum alloy sheet) having anisotropic deformation properties, with tooling which has been designed by predicting flow and deformation of the blank using an analysis which decouples the anisotropic deformation properties of the blank. The method calculates the response of a small amount of the blank using crystal plasticity theory. The blank can be represented as a mesh having a plurality of elements. A strain path is predicted for each element using finite element analysis (FEA), and a stress-strain curve is defined for each element by performing a material point simulator (MPS) calculation for each element using its respective strain path. A second FEA is then carried out on the elements using the respective stress-strain curve for each element. The stress-strain curve for each element may be defined by assigning to each element a curve which lies between an upper bound curve and a lower bound curve, using various methods.

Abstract: A zirconium base alloy is produced, having improved ductility after irradiation with fast neutrons, by heating in a protective atmosphere a zirconium base alloy containing precipitates in the form of at least one alloying element (e.g. Nb, Mo, Ni or Cr), which is soluble with the zirconium in the .beta. phase and insoluble therewith in the .alpha. phase, until the precipitates have dissolved, water quenching the zirconium base alloy to produce a fine martensitic structure supersaturated with the or each alloying element, working the zirconium base alloy in steps reducing the cross-sectional area 10% to 20% of the original cross-section, with annealing below recrystallization temperature for at least 10 minutes in the .alpha. phase between steps, until a total reduction of 70%-75% of the original cross-section is achieved, and then annealing the zirconium base alloy so that simultaneous recrystallization and precipitation of the or each alloying element occurs.