Effect of Working on Heat-Resisting Properties of 316 L Type Steels and 16-15-6 Type Alloys
On the function of nitrogen as an alloying element in heat-resisting materials-VIII
1960 Volume 46 Issue 12 Pages 1559-1563
Details
1960 Volume 46 Issue 12 Pages 1559-1563
This study was carried out to clarify the effect of cold working and “hot-cold” working on the heat-resisting properties of 316L 17Cr-12Ni-2Mo steels and low-Ni Timken 16Cr-15Ni-6Mo (-7·5Mn) type alloys. Main results obtained were as follows:
(1) With both steels containing about 0·2 or 0·3% nitrogen, remarkable increase in hardness was obtained by hot-cold working at 600°C or 700°C as well as by cold working. It was concluded that such hardening was caused by an action similar to strain-aging in the deformed austenite phase supersaturated with nitrogen.
(2) It was deduced from the microscopic observation of the worked steels that the deformation by the working at lower temperature occurred mainly within grains, while the deformation at higher temperature as in the hot-cold working occurred mainly on grain boundaries.
(3) The lower the working temperature and the larger the reduction by working, the easier the softening occurred by heating of the worked steels. With the 16-15-6 type alloys, however, theeffect of working condition on the softening due to the heating of the worked alloys was not so great as the 316L type one.
(4) In general, the cold working deteriorated the bending creep properties at temperatures as high as 700°C of the two steels containing nitrogen, and the hot-cold working also did not improve their creep properties, while both of the workings improved appreciably the properties of the 16-15-6 type alloys not containing nitrogen, which showed in the solutionquenched state little resistance to the bending creep under a definite testing condition of 700°C and of 16kg-load. Under a given reduction by rolling, that is 20%, the hot-cold worked 16-15-6 type alloys with or without nitrogen at 600°C or 700°C showed the larger resisting properties against the bending creep at 700°C compared with those worked at the temperatures higher or lower than those temperatures.
