Dynamic recrystallization of Fe-Cr alloys by atmospheric-controlled induction-heating fine particle peening

Effect of Room Temperature Fine Particle Peening Pretreatment on Grain Refinement of Fe–Cr Alloys by AIH-FPP

“…This is because plastic deformation at high temperature due to IH and the high strain rate due to FPP leads to the occurrence of dynamic recrystallization. 34,35,37) The grains formed at the surface of Fe2%Cr at 973 K were smaller than those obtained at 1073 K. This is because the Zener-Hollomon (Z ) parameter, as discussed later, was higher at 973 K than at 1073 K. In the case of Fe10%Cr, grain refinement occurred at the heating temperature of 1073 K during AIH-FPP whereas no recrystallization could be found at 973 K. Suzuki 42) reported that the addition of Cr to ferrous materials increases their recrystallization temperatures. Therefore, the heating temperature at which fine grains can be formed through dynamic recrystallization increases with the Cr concentration in FeCr alloys.…”

“…Moreover, it was also revealed that grain sizes of the Fe10%Cr were smaller than those of Fe2%Cr when AIH-FPP was performed at 1073 K. This indicates that the addition of Cr to ferrous materials promotes the formation of fine grains during AIH-FPP with the room temperature FPP pretreatment, and this is the same trend as that when only AIH-FPP was performed for the FeCr alloys. 37) To investigate the effect of the number of cycles of the proposed treatment, the FeCr alloys were treated at 1073 K with various cycle numbers. One cycle is equivalent to the thermal cycle shown in Fig.…”

“…36) AIH-FPP can also form fine grains at the surfaces of FeCr alloys. 37) In the AIH-FPP system, FPP can be performed at both room temperature and high temperature in the same chamber. FPP at room temperature can create dislocations with high density and fine grains at the metal surface.…”

Effect of atmospheric‐controlled induction‐heating fine particle peening on microstructure and fatigue properties of low‐alloy steel

“…This is because of severe plastic deformations at high temperatures near the recrystallization temperature and high strain rates caused by AIH-FPP, which led to the occurrence of dynamic recrystallization. 25,26 Some of the grains near the surface could not be detected in the IPF maps because of the introduction of high-density dislocations. In addition, the OM micrograph obtained at a low magnification exhibited that, when α-AIH-FPP was performed at 1023 K, pearlite inside the specimen appeared to be transformed.…”

“…24 It was revealed that AIH-FPP can also refine grains on the surfaces of Fe-Cr alloys. 25,26 The Fe-Cr alloys used in previous studies did not contain carbon and were specially prepared to clarify their dynamic recrystallization behavior. Therefore, the effect of AIH-FPP on the microstructure of practically used steel has not been clarified, and the fatigue properties of AIH-FPPtreated steel have not been also investigated.…”