AISI 4340 Alloy Steel Bar


Standards: ASTM A29



Length: 5.8-12m or random length

Type: Round bar, Hexagonal rods

Heat treatment: Unpolished, Bright

4340 is a low alloy, nickel-chromium-molybdenum Machinery steel capable of being heat-treated to high strength levels. The alloy has a good combination of ductility, toughness and strength along with high hardenability. It has been used for where high strength and heavy-duty are required in heavy sections such as turbine shafts with a diameter greater than 250mm, rotor shafts of helicopters, turboshafts and blades of turbojet engines, high-load transmission parts, crankshaft fasteners, gears, etc.It can also be used for rotor shaft and blade with operating temperature over 400℃; can be used for ultra high strength steel or special purpose after nitriding treatment, low temperature after tempering, or isothermal quenching.


4340 Chemical Composition

C Cr Mn Mo Ni P S Si Co
0.38 – 0.43 0.70 – 0.90 0.65 – 0.85 0.20 – 0.30 1.65 – 2.00 0.04 Max. 0.04 Max. 0.15 – 0.30 /


4340 Equivalent Steel Grade

G43400 36CrNiMo4 816M40 SNCM439 40CrNiMoA


4340 Mechanical Property

Tensile Strength, Mpa Yield Strength, Mpa Elongation Hardness,HB
≥980(100) ≥835(85) ≥12 ≤217HB


Wiho Steel is a fully stocked and leading manufacturer, supplier, exporters, distributors of gear steel in the forms such as plate, sheet, bar and rod. The steel products provide by us shall be fabricated from prime quality raw materials and is fully certifiable to industrial specifications like ASTM and ASME or other relevant standards. Wiho can supply and stock a large inventory of 4340(G43400 /36CrNiMo4/SNCM439)steel round bar, hexagonal bars used for shafts, gears and other mechanical and machining parts. For more information on our extensive steel alloys inventory, please contact us or fill in the form below.

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