The semiaustenitic precipitation-hardenable stainless steels remain austenitic on cooling rom a solution heat treatment at about 1950 F. In this form they are readily fabricable. Subsequent treatment at about 1400 or at about 1725 F depletes the austenite of Cr and C to the extent that martensite forms on cooling to room temperature or -100 F, respectively. Final hardening is effected by tempering, or aging, at 750 to 1100 F. The semiaustenitic precipitation-hardenable stainless steels may be obtained as transformed at the mill by cold rolling. In this condition they lack the good formability of solution-heat-treated material. However, the fabricator need only temper them to obtain very high strengths. These steels have a combination of good formability, high strength, and excellent corrosion resistance that is not easily matched by other materials.

The results of a state-of-the-art survey covering niobium and 18 of its most promising alloys are presented. All data are given in tabular and graphical form covering some of the more important physical, mechanical, and metallurgical properties for each material. References are given at the conclusion of each material section.

This report presents the results of a state-of-the-art survey covering tantalum and seven of its alloys. All data are given in tabular and graphical form covering some of the more important physical, mechanical, and metallurgical properties for each material. References are given at the conclusion of each material section.

The results of a state-of-the-art survey covering tungsten and ten of its alloys are presented. All data are given in tabular and graphical form covering some of the more important physical, mechanical, and metallurgical properties for each material. References are given at the conclusion of each material section.