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).
Examination of chassis road springs for decarburisation after bumper testing.
| Identifier | ExFiles\Box 154a\4\ scan0056 | |
| Date | 3rd February 1938 | |
| To BY. {R.W. Bailey - Chief Engineer} c. Rm. {William Robotham - Chief Engineer} c. Da. {Bernard Day - Chassis Design} H1/EJW.1/GS.3.2.38. LABORATORY. M.1,486. LES 1306 CHASSIS ROAD SPRINGS - DECARBURISATION. The following springs were handed to us by Rm {William Robotham - Chief Engineer} /Les. at your request. Woodhead Spring No.24 Mainplate - broken through eye after 11 1/2 hours on bumper test. Firths Spring No.1 Mainplate - broken about 15 ins. from one end after 20 hours on bumper test. Firths Spring No.2 Mainplate - broken about 15 ins. from one end after 19 hours 40 mins. on bumper test. American Spring - make unknown - small plate. Unused. As requested we have examined sections from each spring for decarburisation. From each Firth's spring the section included the region in which fracture started. This is shown at "X" in photos. M.1,486/1 and M.1,486/2. The section from the Woodhead's spring was taken about four inches from the fracture, i.e. from the plate, not from the broken eye. The attached blue print gives the average depth of decarburisation and indicates the positions of decarburised regions by means of a dotted line. The structure of the decarburised region varies considerably. In the Woodhead spring, photomicrograph M.1,486/3, the surface layer contains ferrite streamers and triangulated ferrite but is obviously not completely decarburised, whereas the American spring has a layer of well formed ferrite grains as shown in photomicrograph M.1,486/5. Small discontinuities and entangled oxide were found in the decarburised layer in the Firth's spring, and the ferrite was in the form of complete grains as shown in photomicrograph M.1,486/4. For comparison with these three photomicrographs, which all represent transverse sections of the springs, we have taken :- M.1,486/6 - Upper surface of Woodhead's Spring after removal of .002" depth of material. Note considerable reduction in amount of ferrite. M.1,486/7 - Upper surface of Firth's Spring No.1 after removal of .002" depth of material. Note almost completely ferritic structure and presence of 1. | ||