High Tensile ASTM 4140 Carbon Alloy Solid Round Bar Round Steel 20mm Carbon Steel Bar for Structure

Oct 29, 2025

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Product Description

1. AISI 4140 Steel Introduction
AISI 4140 is defined as a low alloy steel which has 1% Cr-Mo as strengthening alloy elements.Compared with AISI 4130, it has a higher carbon content with good balance of strength, toughness ,abrasion and impact resistance and heat treatment capabilities,but poor in weldability characteristics.AISI 4140 is generally supplied in quenched and tempered condition with hardness 28-32HRC

2. AISI 4140 Steel Equivalent

Country China Japan Germany USA British
Standard GB/T 3077 JIS G4105 DIN (W-Nr.)
EN 10250
AISI/ASTM
ASTM A29
BS 970
Grade 42CrMo SCM440 42crmo4/1.7225 4140 EN19/709M40


3. AISI 4140 Steel Chemical Composition

Grade C Si Mn P S Cr Mo Ni
42CrMo 0.38-0.45 0.17-0.37 0.5-0.80 ≤0.035 ≤0.035 0.9-1.2 0.15-0.25 -
SCM440 0.38-0.43 0.15-0.35 0.6-0.85 ≤0.035 ≤0.04 0.9-1.2 0.15-0.30 -
42crmo4/1.7225 0.38-0.45 ≤ 0.4 0.6-0.9 ≤0.025 ≤0.035 0.9-1.2 0.15-0.30 -
4140 0.38-0.43 0.15-0.35 0.75-1.00 ≤0.035 ≤0.04 0.8-1.1 0.15-0.25 -
EN19/709M40 0.35-0.45 0.15-0.35 0.5-0.80 ≤0.035 ≤0.035 0.9-1.5 0.2-0.40 -


4. AISI 4140 Steel Mechanical Properties(for guidance only)

Grade Tensile strength
σb(MPa)
Yield strength
σs (MPa)
Elongation
δ5 (%)
Reduction
ψ (%)
Impact Value
Akv (J)
Hardness
4140 ≥1080 ≥930 ≥12 ≥45 ≥63 28-32HRC


5. AISI 4140 Steel Overviews

Size Round Dia 6-1200mm
Plate/Flat/Block Thickness
6mm-500mm
Width
20mm-1000mm
Heat treatment Normalized ; Annealed ; Quenched ; Tempered
Surface condition Black; Peeled; Polished; Machined; Grinded; Turned; Milled
Delivery condition Forged; Hot rolled; Cold drawn
Test Tensile strength, Yield strength, elongation, area of reduction, impact value, hardness, grain size, ultrasonic test, US inspection, magnetic particle testing, etc.
Payment terms T/T;L/C;/Money gram/ Paypal
Trade terms FOB; CIF; C&F; etc..
Delivery time 30-45 days
Application AISI 4140 steel finds many applications as forgings for the aerospace,oil and gas,automotive, agricultural and defense industries etc.
Typical applications for 4140 steel uses include:forged gears,spindles,fixtures,jigs,collars,Axles,conveyor parts,crow bars,logging parts,shafts,sprockets,studs,pinions,pump shafts, rams, and ring gears etc


6. Delivery Condition
For hot forged or hot rolled bar, usually the delivery condition is hot forged or rolled, annealed, rough turned.
For hot forged plate, usually the delivery condition is hot forged, annealed, milled surface.
For hot rolled plate, usually the delivery condition is hot rolled, annealed, black surface

Main Products

Alloy Steel 4140,4142,42CrMo4,1.7225,SCM440,4130,SCM430,25CrMo4,1.7218,34CrNiMo6,
1.6582,4340,SNCM439,36CrNiMo4,1.6511,SACN645,1340,SMn438,SNC236,
Tool Steel H13,1.2344,SKD61,D2,SKD11,1.2379,1.2510,01,SKS3,95MnWCr5,D3,SKD1,1.2419,
SKS31,H21,SKD5,1.2581,P20,35CrMo7,1.2738,1.2316,M2
Bearing Steel GCr15,52100,SUJ1,SUJ2,100Cr6,1.2067,55C,8620,4320,9310,440C,M50
Spring Steel 9260,SUP6,SUP7,1.7108,54SiCr6,1.7102,5155,SUP9,1.7176,5160,1.7177,6150,
SUP10,51CrV4,1.8159
Stainless Steel 321,sus321,1.4541,304,SUS304,1.4301,410,SUS410,1.4006,420,1.4021,1.4028,
434,1.4113,316L,SUS316L,1.4435,630,1.4542,431,1.4057

 

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1.What alloy is structural steel?

Common Alloys for Structural Steel

Some of the most common include: Cold-rolled ASTM-A1008: This is a low-carbon steel that can be created in multiple different formed shapes, such as channel and angle. This makes it excellent for many foundational structural applications.

 

2.Which is better, SS or MS?

Fabrication. As chrome is a hard alloy, stainless steels are much more impact resistant compared to mild steel and (although relatively easy to fabricate) are not as easy to fabricate as mild steel. Mild steel is much more malleable compared to stainless and so is used a lot in general fabrication.

 

3.What is structural alloy?

Structural-alloys is a term used in the construction and building industry to refer to metals that are specifically designed and engineered for use in load-bearing structures.

 

4.What is alloy steel?

Alloy steel is steel that is alloyed with a variety of elements in amounts between 1.0% and 50% by weight, typically to improve its mechanical properties.

 

5.Is MS stronger than SS?

Stainless steels is designed with a higher content of chromium with other constituent alloys like copper, nitrogen, nickel, molybdenum, and a few others. SS is stronger than alloys of mild steel.