1.AISI 4140/DIN 1.7225/JIS SCM440 Introduction:
Alloy steels are designated by AISI four-digit numbers. They comprise different kinds of steels having composition exceeding the limitations of B, C, Mn, Mo, Ni, Si, Cr, and Va set for carbon steels.
AISI 4140 alloy steel is chromium, molybdenum, manganese containing low alloy steel. It has high fatigue strength, abrasion and impact resistance, toughness, and torsional strength.

2.Fabrication and Heat Treatment:

Machinability:
AISI 4140 alloy steel has good machinability in the annealed condition.

Forming:
AISI 4140 alloy steel has high ductility. It can be formed using conventional techniques in the annealed condition. It requires more pressure or force for forming because it is tougher than plain carbon steels.
Welding:
AISI 4140 alloy steel can be welded using all conventional techniques. However, the mechanical properties of this steel will be affected if it is welded in the heat treated condition, and post weld heat treatment should be performed.
Heat Treatment:
AISI 4140 alloy steel is heated at 845°C (1550°F) followed by quenching in oil. Before hardening, it can be normalized by heating at 913°C (1675°F) for a long period of time followed by air cooling.
Forging:
AISI 4140 alloy steel is forged at 926 to 1205°C (1700 to 2200°F)
Hot Working:
AISI 4140 alloy steel can be hot worked at 816 to 1038°C (1500 to 1900°F)
Cold Working:
AISI 4140 alloy steel can be cold worked using conventional methods in the annealed condition.
Annealing:
AISI 4140 alloy steel is annealed at 872°C (1600°F) followed by slowly cooling in the furnace.
Tempering:
AISI 4140 alloy steel can be tempered at 205 to 649°C (400 to 1200°F) depending upon the desired hardness level. The hardness of the steel can be increased if it has lower tempering temperature. For example, tensile strength of 225 ksi cab be achieved by tempering at 316°C (600°F), and a tensile strength of 130 ksi can be achieved by tempering at 538°C (1000°F).
Hardening:
AISI 4140 alloy steel can be hardened by cold working, or heating and quenching.

3.AVAILABLE SIZE:
Round bar: Diameter(mm) Max 800mm; Length(mm) Max 12000mm.
Plate: Thickness(mm) Max 800mm; Width(mm) Max 2300mm; Length(mm) Max 12000mm.
Condition: Cold rolled(drawn)≤50mm, Hot rolled≤12-250mm, Hot forged≥50mm.(Thickness/Diameter)

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