AISI 5140 alloy steel is a structural alloyed carbon steel accding to AISI/ASTM standard which is widely used in Low and moderately stressed parts for vehicles, engines and machines where hard, wear resisting surface is needed. The hardness as surface hardened is about 54 HRC.

CHEMICAL COMPOSITION

HEAT TREATMENT OPTION

• +A: Annealed (full/soft/spheroidizing)
• +N: Normalized
• +NT: Normalized and tempered
• +QT: Quenched and tempered (water/oil)

FABRICATION AND HEAT TREATMENT

Machinability
Long, gummy chips characterize this alloys machinability. It can be machined in the annealed condition, however condition H1150M will yield best results. Post machining solution treatment of parts will be required prior to final hardening if machining in this condition.

Successfully welded by common fusion and resistance methods, this alloy should not be joined by oxyacetylene welding. AWS E/ER630 filler metal is recommended if required.

Heat Treatment
CONDITION A--Soak at 1900 F (1038 C) for 30 minutes and cool below 60 F (16 C) for complete martensite transformation. CONDITION H 950- Treat Condition A material at 900 F(482 C) for 1 hour, air cool.. CONDITION H925, H1025, H1075, H1100, H1150- Soak solution treated material for 4 hours at specified temperature, air cool, CONDITION H1150M- Soak solution treated material at 1400 F (760 C) for 2 hours, air cool, then re-heat to 1150 F (620 C) for 4 hours and air cool.

Forging
Soak for 1 hour at 2150 F (1177 C) prior to forging. Do not work below 1850 F (1010 C). Post-work solution treatment is required prior to final hardening.

Soft Annealing
Heat to 680-720℃, cool slowly. This will produce a maximum 5140 hardness of 241HB (Brinell hardness).

Tempering
Tempering temperature: 540-680℃.

Noramlizing of steel grade 5140

Temperature: 840-880℃

Hardening
Harden from a temperature of 820-850, 830-860℃ followed by water or oil quenching.