Fig. 46 AISI O1. Influence of austenitizing temperature on microstructure. (a) Austenitized at 800 °C (1475 °F) 1 h for every 25 mm (1.0 in.) of thickness. 65 HRC, grain size 9.5. Specimen properly austenitized. (b) Austenitized at 870 °C (1600 °F). 65 HRC, grain size 9. Overaustenitized. (c More

Fig. 30 Light micrograph of overaustenitized AISI O1 tool steel containing coarse plate martensite and substantial unstable retained austenite. Specimen etched with nital More

Fig. 34 Light micrograph of a grossly overaustenitized AISI D2 draw die insert. Specimen etched with Marble's reagent More

Fig. 8 AISI W1 (1% C) overaustenitized at 925 °C (1700 °F) and water quenched, producing martensite, retained austenite, and small patches of pearlite. Influence of etchant on revealing quenched martensite. (a) 2% nital etch reveals martensite and pearlite (black). (b) 4% picral etch reveals More

Fig. 39 Light micrograph of overaustenitized AISI O1 tool steel containing coarse plate martensite and substantial unstable retained austenite. Specimen etched with nital More

Fig. 43 Light micrograph of a grossly overaustenitized AISI D2 draw die insert. Specimen etched with Marble’s reagent More

Fig. 16(a) AISI O1 tool steel ring forging that cracked during quenching. The forging was overaustenitized (unstable retained austenite was present) and was decarburized to a depth of about 0.5 mm (0.020 in.). Temper color was present on the crack walls. See also Fig. 16(b) . More

Fig. 17 AISI M2 roughing tool that cracked just after heat treatment. (a) Cracks accentuated with magnetic particles. (b) Microstructural examination revealed a badly overaustenitized condition with a heavy grain-boundary carbide film, coarse plate martensite, and unstable retained austenite More

Fig. 17 AISI M2 roughing tool that cracked just after heat treatment. (a) Cracks accentuated with magnetic particles. (b) Microstructural examination revealed a badly overaustenitized condition with a heavy grain-boundary carbide film, coarse plate martensite, and unstable retained austenite More

Fig. 18 AISI O6 graphitic tool steel punch machined from centerless-ground bar stock that cracked after limited service. (a) Cracks (arrows) accentuated with magnetic particles. (b) Microstructural examination revealed an overaustenitized structure consisting of appreciable retained austenite More

Fig. 18 AISI O6 graphitic tool steel punch machined from centerless-ground bar stock that cracked after limited service. (a) Cracks (arrows) accentuated with magnetic particles. (b) Microstructural examination revealed an overaustenitized structure consisting of appreciable retained austenite More

Fig. 5 AISI 06 graphitic tool steel punch machined from centerless-ground bar stock that cracked after limited service. (a) Direction of cracking, as indicated by the arrows, was accentuated with magnetic particles. (b) Microstructural examination revealed an overaustenitized structure More

overaustenitized structure about 19 mm (0.75 in.) below the surface. All etched with 3% nital. All 700× More

overaustenitized structure approximately 19 mm (0.75 in.) below the surface. All etched with 3% nital. Original magnification of all: 700× More

Fig. 21 Failed AISI S7 jewelry striking die. (a) Crack (arrows) that formed shortly after the die was placed in service. (b) and (c) Microstructural examination revealed that the surface was slightly carburized and that the die had been overaustenitized. Note the coarse plate martensite More

temperature of 940 °C (1725 °F). (d) Austenitized at 955 °C (1750 °F). Slightly overaustenitized; note coarsening, no visible carbide. 4% picral. 500× More

Fig. 21 Failed AISI S7 jewelry striking die. (a) Crack (arrows) that formed shortly after the die was placed in service. (b) and (c) Microstructural examination revealed that the surface was slightly carburized and that the die had been overaustenitized. Note the coarse plate martensite More

Fig. 16 (a) AISI O1 tool steel ring forging that cracked during quenching. The forging was overaustenitized (unstable retained austenite was present) and was decarburized to a depth of approximately 0.5 mm (0.020 in.). Temper color was present on the crack walls. (b) Interior microstructure More

. (b) Etching the surface with 10% aqueous nitric acid revealed a white-etching appearance at the teeth. 2×. (c) Micrograph showing a surface layer of as-quenched martensite (from the EDM operation) and an overaustenitized matrix structure (unstable retained austenite and coarse plate martensite More

. (b) Etching the surface with 10% aqueous nitric acid revealed a white-etching appearance at the teeth. Original magnification: 2×. (c) Micrograph showing a surface layer of as-quenched martensite (from the electrical discharge machining operation) and an overaustenitized matrix structure (unstable More