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The effect of steam treatment on the physical properties of powder metal parts was studied. Steam treatment increases the weight, size, density, and hardness of the parts. The strength measured in tests of standard transverse rupture specimens is not significantly affected by steam treatment. However the ductility, as measured by the deflection, is decreased after steam treatment. Part crush load can be, depending on the configuration, significantly decreased or slightly increased. Steam treatment is most effective in the first half hour. The effect of further increasing steam treatment time is not significant.

Since aluminum alloys have been widely used as structural materials in various mobility related industries, many studies concerning fatigue damage, and the growth behavior of long cracks in particular, have been conducted on these materials. However, the fatigue life of most land-vehicle structural components is controlled mainly by the growth behavior of small cracks which cannot be treated by long-crack methods such as linear elastic fracture mechanics. The behavior of small cracks must be studied to evaluate the fatigue life of these structures. In the present paper, the initiation and growth behavior of small cracks in plain specimens of 6061-T6 aluminum alloy are investigated. It was observed that a surface shear crack usually initiated within a grain, and its subsequent growth depended strongly on the microstructure. With regard to the crack growth behavior, multiple cracks generally initiated and grew to surface lengths exceeding 1 mm before fracture.