AISI 4140 steel manufacturing ASTM AISI 4140 steel manufacturing supplier

What is AISI 4140 Steel?

AISI 4140 alloy steel round bar sheet plate belongs to medium hardenability
steel.AISI 4140 steel has high fatigue strength and low notch sensitivity. Low-
temperature impact toughness is also very high, no obvious temper brittleness.
AISI 4140 steel round bar is mainly used after quenching and tempering state.
it is used to manufacture high-strength parts under impact loads and the
fittings with large cross-sections and other stressed members. Such as the
horizontal eccentric shaft of the horizontal forging machine, the crankshaft of
the forging press, and etc.
Its equivalent grade is JIS SCM440 and DIN 1.7225. The properties and
composition of 4140 steel round bar sheet plate as below.

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.



AISI 4140/DIN 1.7225 Introduction:

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.



Fabrication and Heat Treatment:

1. Forging

Preheat the steel carefully, then raise the temperature to 1150-1200°C for
forging. Do not forge below 850°C.

2. Annealing

Heat the AISI 4140 slowly to 800-850°C and allow enough time for the steel to
be thoroughly heated. Cool slowly in the furnace to 480°C followed by air
cooling.

3. Stress Relieving

When parts are heavily machined, ground or otherwise subject to cold work,
stress relieving will be beneficial prior to hardening.

4. Hardening

AISI 4140 steel is usually supplied ready heat treated to 18-22HRC. If further
heat treatment is required annealed AISI 4140 should be heated slowly to 840-
875°C and after adequate soaking at this temperature quench in oil. Temper as
soon as the tools reach room temperature.

5. Tempering

Heat the AISI 4140 carefully to a suitable temperature selected by reference to
a tempering chart or table (usually between 550-700°C, soak at the temperature
for 2 hours per 25mm of ruling section, then allow to cool in air. Tempering
between 250-375°C is not advised as tempering within this range will seriously
reduce the impact value.

6. Surface Treatment

Plate: Origin Black, Orign cold rolled bright, Machined, Grinded

Bar: Origin Black, Orign cold rolled(drawn) bright, Turned, Peeled, Grinded

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Minimum Order: 1 tons

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