Fig. 7 Flow lines in a forged 4140 steel hook. Specimen was etched using 50% HCl. 0.5× More

Fig. 5 Compressive flow curve for 4140 alloy steel at room temperature. Large strain was achieved by removing the barreling by machining after 40% strain and then continuing the test. Source: Ref 7 More

Fig. 19 Flow lines in a forged 4140 steel hook. Specimen was etched using 50% HCl. Original magnification 0.5× More

Fig. 23 Flow lines in a forged 4140 steel hook. Specimen was etched using 50% HCl. 0.5x More

Fig. 35 Micrograph of AISI 4140 steel as quenched and tempered. The microstructure is tempered martensite with evidence of decarburization and high-temperature oxidation on the surface of the crack profile. 50×; 2% nital etch. Source: Ref 27 More

Fig. 36 Micrograph of AISI 4140 steel as quenched and tempered. The microstructure is tempered martensite with intergranular quench cracking along the prior austenite grain boundaries. 100×; 2% nital etch. Source: Ref 27 More

Fig. 42 Micrograph of AISI 4140 steel as quenched and tempered. The microstructure is tempered martensite with quench cracking in the area of dimensional change. 91×; 2% nital etch. Source: Ref 27 More

Fig. 44 Micrograph of AISI 4140 steel as quenched and tempered. The microstructure is tempered martensite with quench cracking initiating from a machine groove. 100×; 2% nital etch. Source: Ref 27 More

Fig. 71 Micrograph of AISI 4140 steel as quenched and tempered; microstructure is tempered martensite, where cracking is promoted by alloy depletion. 91×; 2% nital etch. Source: Ref 27 More

Fig. 86 Micrograph of AISI 4140 steel as quenched and tempered, showing bands of tempered martensite and tempered martensite/bainite. 50×; 2% nital etch. Source: Ref 27 More

Fig. 87 Micrograph of AISI 4140 steel as quenched and tempered. Microstructure shows banded martensite and tempered martensite/bainite. Subsurface cracking is illustrated. 100×; 2% nital etch. Source: Ref 27 More

Fig. 15 “Tire tracks” on a fatigue fracture surface of a 4140 steel quenched and tempered at 700 °C (1292 °F) More

Fig. 12 Hardness and notch toughness of 4140 steel tempered for 1 h at various temperatures More

Fig. 10 Bending fatigue S - N curves for AISI 4140 specimens having normal and inverse hardness distributions after quenching. All specimens were tempered for 2 h at 500 °C. Source: Ref 6 More

Fig. 15 Tempering curves for (a) 4140 and (b) 4340 steels. Source: Ref 17 More

Fig. 8 Continuous-cooling transformation diagrams for AISI (a) 4140 and (b) 4340 steels More

Fig. 5 Cooling curve measured at the centerline of an AISI 4140 cylindrical probe quenched in a fluidized bed (alumina plus air at room temperature) and with a fluidization number of 1.4. Source Ref 31 More

Fig. 3 Results of liquid pressure nitriding on SAE 4140 low-alloy steel (composition, 0.38C-0.89Mn-1.03Cr-0.18Mo; core hardness, 35 HRC) More

Fig. 13 Comparison of case depth vs. process time for ion and gas nitriding of 4140 steel. Source: Ref 18 More

Fig. 20 Compound layer on the ion-nitrided surface of quenched and tempered 4140 steel. The compound layer is supported by a diffused case, which is not observable in this micrograph. Nital etched. Original magnification: 500× More