Calculation of Aluminum Equivalent Based on Thermo-Calc Software in Ti-Al-Nb Ternary System

Ti-Al-Nb ternary phase diagrams were calculated by Thermo-Calc software. The analysis of the calculated vertical sections of Ti-Al-Nb phase diagram indicated that when Nb content is fixed at 5at.% and Al content is lower than 52.3at.%, the primary phase would be β phase during solidification. With 10 at.%Nb and Al content lower than 55.8at.%, or with 15 at.%Nb and Al content lower than 56.9at.%, the primary phase would be β phase. The vertical sections of Ti-Al-Nb ternary phase diagram were further simplified into pseudo-Ti-Al binary phase diagram. According to the pseudo-Ti-Al diagram, the expression of the aluminum equivalent was obtained in Ti-Al-5Nb ternary alloys.

Aluminum Applications to Naval Ship Design and Shipbuilding

In an earlier paper, the authors conducted an analysis of the difference in acquisition and total ownership costs of steel and aluminum equivalent naval ship designs. It was shown that an aluminum ship can be built within just 7.5% of the acquisition cost of an equivalent steel ship. This is possible because of the cascading benefits of the aluminum ship’s significantly lighter weight. The aluminum ship was also shown to have operational and total ownership cost advantages. This paper reports on additional design effort conducted by the authors that validates the structural and fire insulation weight estimates used for both ship designs in the earlier paper.

The Effect of Aluminum Equivalent and Molybdenum Equivalent on the Mechanical Properties of High Strength and High Toughness Titanium Alloys

The effect of Aluminum equivalent and Molybdenum equivalent on the strength and fracture toughness of titanium alloys was studied in this paper. The result shows that the tensile strength of the alloy increases with increasing of aluminum equivalent and molybdenum equivalent and the fracture toughness decreases gradually, the effect of aluminum equivalent is comparatively more conspicuous. A suitable value range of aluminum equivalent and molybdenum equivalent of high strength and high toughness titanium alloys are obtained from the analysis, based on this, a new type of high strength and high toughness titanium alloy BTi-6554 (Ti-4Al-5Mo-5V-6Cr) was developed, which has good combination of strength and fracture toughness and has the characteristics of high strength and high toughness.