Structural titanium alloys are coming in for increased use because they are light, ductile and have good fatigue and corrosion-resistance properties As a result, more manufacturing engineers are learning that machining these alloys can be a tricky job due to their unique physical and chemical properties. The problems that arise in drilling, turning, and grinding of titanium can be better understood if we look at these properties. They hold the key to successful machining operations. The specific weight of titanium is about two thirds that of steel and about 60 percent higher than that of aluminum. In tensile and sheet stiffness, titanium falls between steel and aluminum. But titanium's strength (80,000 PSI for pure titanium and 150,000 PSI and above for its alloys) is far greater than that of many alloy steels, giving it the highest strength-to-weight ratio of any of today's structural metals.

Thermal properties are another matter. Titanium alloys have high melting points, which is usually a sign of excellent temperature stability. However the strengths of titanium alloys fall off rapidly at temperatures above 800 degrees F, and their coefficients of expansion are even less than that for steels. These unusually poor thermal properties account, to a large extent, for the difficulties in machining titanium.

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