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inspection and testing
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Table I shows the ultimate tensile strength and minimum permissible elongation for the most important materials used in locomotive construction.
| Name and use of Material. | Ultimate tensile strength tons per sq. in. |
Percentage elongation above original length not less than |
| Mild steel boiler plates | 26 to 32 | 22% in 8 ins. |
| Mild steel boiler rivets | 24 to 28 | 27% in 8 diameters |
| Mild steel frame plates | 28 to 32 | 20% in 8 ins. |
| Steel crank axles | not less than 30 | 20% in 2 ins. |
| Steel crank axles, oil treated | not less than 35 | 20% in 2 ins. |
| Steel straight axles | 25 to 40 | 25% to 20% in 2 in. |
| Steel tyres, class C | 50 to 55 | 13% to 11% in 2 ins. |
| Steel tyres, class D | 56 to 62 | 10% to 8% in 2 ins. |
| Steel castings with wearing surfaces | not less than 35 | 10% in 2 ins. |
| Cast steel wheel centres. | not less than 26 | 15% in 2 ins. |
| Copper plates for fireboxes | not less than 14 | 35% in 8 ins. |
| Copper stays for fireboxes | not less than 14 | 40% in 8 diameters |
| Mild steel tubes for boilers | not more than 24 | 28% in 8 ins, |
| “Best Yorkshire” iron bars, 1 in. to 4 ins. diameter |
21 to 23½ | varies according to bars. |
Spring steel is not usually tested for tensile strength, but the springs are subjected to rapid deflection tests.
Bending Tests. Other tests specified include “cold bend” and “temper bend” tests. In the former, specimens cut from plates are doubled over cold, until the internal radius is not greater than the thickness of the plate, and the test piece must withstand this without fracture. The “temper bend” test is similar, but the piece is heated beforehand to a red heat and quenched
