TABLE OF CONTENTS The applications of tin are governed very largely by its low melting point, excellent fluidity when molten, relative softness, formability and readiness to form alloys with other metals.
The low melting point of tin means that at normal ambient temperature the metal is nearly 60% of its melting point on the absolute Temperature Scale. This results in rather low mechanical strength at room temperature, as would be expected from any metal tested at a temperature corresponding to such a high proportion of its Absolute melting point, i.e. 505 K. Because of this, pure tin recrystallises readily at room temperature. Consequently, unlike the majority of industrial metals, only slight work hardening occurs initially in tin, followed by work-softening with further deformation due to grain growth. A similar behaviour is found in tin-rich alloys. The mechanical properties recorded for tin-rich alloys are strongly dependent on impurity levels and the strain rate.
Within reasonable limits any tin-base alloy can be die cast successfully. The choice of alloy, therefore, rests on such matters as mechanical properties, wear resistance or cost rather than on any consideration of the casting behaviour.
| PURE TIN MECHANICAL PROPERTIES | |||
|---|---|---|---|
| Tensile strength (at 0.4 mm/mm min) at | 20 C | 14.5 MPa | |
| 100 C | 11.0 Nmm -2 | ||
| 200 C | 4.5 Nmm -2 | ||
| Shear strength at 20 C | 12.3 MPa | ||
| Hardness at | 20 C | 3.9HB | |
| 100 C | 2.3 HB | ||
| 200 C | 0.9 HB | ||
| Young's modulus at 20 C | 49.9 GPa | ||
| Rigidity modulus at 20 C | 18.4GPa | ||
| Poisson's ratio |
