Behavior of sulfide inclusions during thermomechanical processing of AISI 4340 steel

Nucleation of Acicular Ferrite on Sulfide Inclusion during Rapid Solidification of Low Carbon Steel

“…30) Sulfides are formed in the alloys by sulfur transfer from slag to surrounding matrix, and Mn concentration in matrix decreased rapidly. For example, a Mn-depleted zone with width about 50 mm is observed in the matrix surrounding FeS slag in 0.7 % Mn-Fe alloy after annealing at 1 473 K for 1 h. Almost similar width Mn-depleted zone is also observed by Murty 29) in AISI 4340 steel when homogenized at 1 583 K for 2 h. Recently Shigesato 28) has investigated the Mn-depleted zone formed around MnS particles in austenite in transformation of acicular ferrite in low alloy steel subjected to simulated thermal cycle of weld HAZ. The sample, which is hold at 1 713 K for 4 s, is rapidly cooled (He gas) to 1 373 K and hold at that temperature for 100 S, and then rapidly cooled to 823 K for 30 s followed by rapidly cooling to room temperature.…”

“…The secondary dendrite arm spacing, d II , is about (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) mm in the sample. The cooling rate on solidification of the present sample could be estimated as about ϳ300 K/s based on the following equation, 13) where R is the cooling rate on the solidification in K/s.…”

“…As a result, the matrix surrounding the sulfide phase is depleted in Mn during slow cooling and homogenization. 29) The Mn-depleted zone adjacent to FeS phase has been directly measured by several researchers. A synthetic FeS slag is embedded into various Mn-Fe alloys and the solid state reaction between them were studied at 1 373-1 723 K by Hisada.…”

Effect of Heat Treatment Conditions on Shape Control of Large-sized Elongated MnS Inclusions in Resulfurized Free-cutting Steels

“…After that, Gnanamuthu 2) concerned with different types of MnS and found all MnS inclusions finally changed to polyhedron after long time soaking. Murty [3][4][5] found there were three stages for the evolution of elongated type II and III MnS in high sulfur steel: (1) cylinderization (2) ovulation (3) coarsening. Then Mcfarland 6) paid attention to the spheroidization of type II MnS with the homogenization.…”

Investment casting nickel-beryllium alloys

“…The unidirectional solidification experiments to determine the baseline dendrite arm spacing versus cooling rate relationship were conducted in an insulated Fiber Frax mold with water-cooled copper chill placed at the bottom. 3 This arrangement is designed to produce a maximum temperature gradient in the heat flow direction. The investment-cast part studied was an engineering bracket made by a shell investment molding process.…”