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).
Analysis of microphotographs from a cracked Wraith Cylinder Head valve seat to investigate its material structure.
| Identifier | ExFiles\Box 10\3\ 03-page189 | |
| Date | 7th October 1939 | |
| S. BR.{T. E. Bellringer - Repair Manager} RHC{R. H. Coverley - Production Engineer}/Ve.S/EP.{G. Eric Platford - Chief Quality Engineer}7.10.39. Handwritten note: for Mr Stoll Iron Foundry. Handwritten number: 654 We attach herewith as requested microphotographs taken from the valve seat of the actual Wraith Cylinder Head which cracked in service. The photographs were taken within 0.175 ins. of the crack itself and can therefore be said to be representative of the structure of the material of the actual seat which failed. The microphotographs show the condition of the material in the unetched and etched conditions. In the unetched condition magnified 100 times, the Graphite flakes are very well distributed and curly which is the required condition for the part, and are typical of a High Duty Cast Iron as agreed by the British Cast Iron Research Association. In the etched condition magnified 200 times, the size and distribution of the Graphite and phosphide areas and the condition of the matrix which is Pearlitic indicate a very satisfactory structure, and no unusual condition is present to which the cracking may be attributed from the material structure or composition point of view. RHC{R. H. Coverley - Production Engineer}/Ve. [Signature illegible, possibly Thackeray] | ||