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AISI 4340 Steel Round Bar - High Tensile Strength, Shock and Impact Resistant, Wear and Abrasion Resistant

Minimum Order Quantity	1 Ton
Price	US $720-1,430 / Ton

Product Details

Diameter Range	6-630mm	Carbon Content	0.38-0.43%
Manganese Content	0.60-0.80%	Phosphorus Content	0.035%
Sulfur Content	0.040%	Silicon Content	0.15-0.35%
Nickel Content	1.65-2.00%	Chromium Content	0.70-0.90%
Molybdenum Content	0.20-0.30%	Tensile Strength	930-1080 MPa
Yield Strength	740 MPa	Elongation	12%
Impact Resistance	47 J	Brinell Hardness	269-331 HB
Thermal Conductivity	44.5 W/mK
Highlight	High Tensile Strength AISI 4340 Steel Round Bar , Shock and Impact Resistant 40CrNiMoA Round Bar , Wear and Abrasion Resistant SNCM439 Alloy Steel Bar

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Product Description

40CrNiMoA BS S535/AMS 6350 AISI 4340 Round Bar JIS Sncm439

AISI 4340 steel is a medium carbon, low alloy steel known for its exceptional toughness and strength in relatively large sections. As a nickel chromium molybdenum steel, 4340 alloy steel is typically supplied hardened and tempered in the tensile range of 930-1080 Mpa. This material offers excellent shock and impact resistance along with superior wear and abrasion resistance in the hardened condition.

Specifications and Standards

Country	USA	Britain	Britain	Japan
Standard	ASTM A29	EN 10250	BS 970	JIS G4103
Grades	4340	36CrNiMo4/1.6511	EN24/817M40	SNCM 439/SNCM8

Chemical Composition

Standard	Grade	C	Mn	P	S	Si	Ni	Cr	Mo
ASTM A29	4340	0.38-0.43	0.60-0.80	0.035	0.040	0.15-0.35	1.65-2.00	0.70-0.90	0.20-0.30
EN 10250	36CrNiMo4/1.6511	0.32-0.40	0.50-0.80	0.035	0.035	<=0.40	0.90-1.20	0.90-1.2	0.15-0.30
BS 970	EN24/817M40	0.36-0.44	0.45-0.70	0.035	0.040	0.1-0.40	1.3-1.7	1.00-1.40	0.20-0.35
JIS G4103	SNCM 439/SNCM8	0.36-0.43	0.60-0.90	0.030	0.030	0.15-0.35	1.60-2.00	0.60-1.00	0.15-0.30

Mechanical Properties

Condition	Ruling Section (mm)	Tensile Strength (MPa)	Yield Strength (MPa)	Elongation (%)	Izod Impact (J)	Brinell Hardness
T	250	850-1000	635	13	40	248-302
T	150	850-1000	665	13	54	248-302
U	100	930-1080	740	12	47	269-331
V	63	1000-1150	835	12	47	293-352
W	30	1080-1230	925	11	41	311-375
X	30	1150-1300	1005	10	34	341-401
Y	30	1230-1380	1080	10	24	363-429
Z	30	1555-	1125	5	10	444-

Thermal Properties

Properties	Metric	Imperial
Thermal expansion co-efficient	12.3 µm/m°C	6.83 µin/in°F
Thermal conductivity	44.5 W/mK	309 BTU in/hr.ft².°F

Heat Treatment Processes

Forging

Preheat 4340 steel to 1150°C - 1200°C maximum for forging, holding until temperature is uniform throughout the section. Do not forge below 850°C. Following forging, cool the workpiece as slowly as possible in sand or dry lime to prevent cracking.

Stress Relieving

Heat to 600°C - 650°C, hold until uniform temperature, soak for 1 hour per 25mm section, and cool in still air.

Annealing

Full anneal at 844°C (1550°F) followed by controlled furnace cooling at a rate not faster than 10°C (50°F) per hour down to 315°C (600°F), then air cool.

Tempering

Temper at 232°C (450°F) for 260-280 ksi strength range, or at 510°C (950°F) for 125-200 ksi strength range. Avoid tempering between 250°C - 450°C due to temper brittleness.

Surface Hardening

Pre-hardened 4340 steel can be surface hardened by flame or induction hardening, achieving case hardness exceeding Rc 50. Heat quickly to 830°C - 860°C followed by oil or water quenching.

Nitriding

Hardened and tempered 4340 can be nitrided at 500°C - 530°C for 10-60 hours, achieving surface hardness of 600-650HV with minimal effect on core tensile strength.

Machining and Welding

Machining is best performed in the annealed or normalized and tempered condition. In high strength conditions (200 ksi or greater), machinability decreases to 25-10% of the annealed condition. Welding in hardened and tempered condition is not recommended. If necessary, pre-heat to 200-300°C and stress relieve at 550-650°C after welding.

Applications

Aircraft Landing Gear
Automotive Components
Oil and Gas Drilling Equipment
Forging Applications
Machine Building
Power Transmission Gears and Shafts
Heavy Duty Shafts, Axles, Spindles
Couplings, Pins, Chucks, Molds

Available Sizes and Conditions

Round Bar Diameter: 12-380mm
Available in round bars, flat bars, plates, and blocks in various conditions including pre-hardened, hot rolled, annealed, quenched and tempered, with surface conditions from black to pre-machined, grinding, and polish.

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Why Choose Our 4340 Steel

Quality Assurance
Materials sourced directly from government-owned steel mills with ISO 9001 certified quality management system.

Timely Delivery
Speedy processing and delivery for both raw materials and finished products with machining or heat treatment.

Comprehensive Services
Value-adding services including metal cutting, sizing, machining, heat treatment, and sawing for any quantity.

Extensive Inventory
Unique inventory of specialty steel with orders of any size or length accommodated.

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AISI 4340 Steel Round Bar - High Tensile Strength, Shock and Impact Resistant, Wear and Abrasion Resistant

High Tensile Strength AISI 4340 Steel Round Bar

Shock and Impact Resistant 40CrNiMoA Round Bar

Wear and Abrasion Resistant SNCM439 Alloy Steel Bar