The Effect of Cold Working on Creep Rupture Strength and Microstructure of Ni-23Cr-7W Alloy
World Journal of Mechanics
In order to clarify the reason why the creep rupture time of pre-strained Ni-23Cr-7W Alloy (HR6W) is longer than that of the non-pre-strained HR6W, microstructures of HR6W after a series of creep tests were investigated. The creep tests were conducted at 750˚C, 90 and 100 MPa. In the pre-strained samples, the grain boundary shielding ratio by precipitates was larger than that of the non-pre-strained sample. In addition, in the pre-strained samples the size of the M 23 C 6 carbide in the grains
... bide in the grains was finer than in the non-pre-strained sample. The W content in the M 23 C 6 carbide in the pre-strained samples tended to be larger than in the non-pre-strained sample. Therefore, the Ostwald ripening of the carbide was delayed and the size of M 23 C 6 carbide was thought to be fine for a long time. These observations show that creep strength in the pre-strained samples is higher than that of the non-pre-strained sample because of both precipitation strengthening inside of the grains and grain boundaries. Keywords A-USC, HR6W, Cold Working, Creep Strength, Grain Boundary Shielding Ratio, M 23 C 6 Carbide structure of Ni-23Cr-7W Alloy. World Journal of Mechanics, 7, 283-295.