Materials for engineering, 3rd Edition - (Malestrom)

Metals and alloys 95
Table 3.5 Typical mechanical properties of some titanium alloys
Alloy Condition Density Young’s Proof UTS Elongation
(Mg m –3 ) modulus stress (MPa) (% in 50 mm)
(GPa) (MPa)
Commercially Annealed 4.51 ~105 540 640 24
pure Ti (α)
(IMI155)
Ti–6Al–4V(α/β) Annealed 4.46 ~106 925 990 14
(IMI318)
Ti–13Mo–11Cr– Aged 4.87 ~106 1200 1280 8
3Al (β)
so, for a given component, a designer can select an alloy before deciding on
the manufacturing process. We will consider this family in three groups: the
grades of copper itself, then the high-copper alloys and, finally, the alloys
containing larger quantities of alloying elements.
Grades of copper
Tough pitch copper contains residual oxygen from the refining process,
including oxide particles, which makes it unsuitable for tube manufacture or
for welding. Deoxidized copper is more appropriate for such applications
and small additions of phosphorus or another deoxidizer is made for this
purpose. If residual deoxidizer remains in solid solution, the electrical
conductivity of the copper is impaired, so high conductivity copper is refined
and deoxidized to a high degree of purity for use in electrical applications.
Copper alloys of low solute content
Arsenical copper contains up to 0.5% As, which has the effect of reducing
the tendency of the metal to scale when heated and also gives a slight
increase in high-temperature strength through solute hardening.
Free-cutting copper contains ~0.5% Te which gives rise to the presence
of second-phase particles of a telluride phase. During machining, these particles
cause the swarf and chippings to break up into small fragments allowing the
cutting fluid access to the interface between the workpiece and the tool. This
increases tool life for a given rate of machining; sulphur-bearing alloys are
also available for the same purpose.
Copper–beryllium alloys are age-hardenable, as suggested by the phase
diagram of Fig. 3.14. Alloys contain typically 1.9% Be and are subjected to
the normal sequence of solution treatment at 800 °C, quenched and artificially
aged in the range 300–320 °C to precipitate the intermetallic phase CuBe.
The alloys also normally contain