From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
The use of the Vickers Hardness Tester for evaluating nitrided components.
| Identifier | ExFiles\Box 154a\1\ scan0121 | |
| Date | 27th November 1928 guessed | |
| -2- The Vickers Diamond Hardness Tester is in our judgment the best available instrument for demonstrating the fitness of the nitrided case for service. The tapering hardness is of course, objectionable but we find the error to be outside the realm of practical importance, with the work we have done to date. Pulling small wires, bending thin strips, pulling thin strips, and pulling thin tubes, for measuring ductility were abandoned after extensive tests, in favour of the Vickers machine. When the time comes that it seems to be essential to evaluate the proportional limit, ultimate strength, and modulus of elasticity of the nitrided case, the thin-walled tubular tension test piece offers the best means that we have been able to devise to date. Our service life tests have convinced us that it is essential to have a fairly definite plastic flow or ductility in the case, and that when the Vickers indentation spalls, the life of the product will be definitely inferior. Thus we have found a practical control test for nitrided products intended for wear-resistance service. We are convinced, that unless some logical 100-per-cent test is applied to important nitrided products, there is a real chance of enough scattered failures occurring to unduly discredit the nitrided product. We further believe that in particularly vital heats good practice will call for the inclusion in the furnace of test pieces to be explored for hardness and penetration. When this is done, those responsible for production will have thoroughly reliable assurance of the quality of their product. | ||