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AISI 4340 Steel 36CrNiMo4 1.6511 EN24 817M40 SNCM439

AISI 4340 steel is a medium carbon, low alloy steel known for its toughness and strength in relatively large sections. AISI 4340 is also one kind of nickel chromium molybdenum steels. 4340 alloy steel is generally supplied hardened and tempered in the tensile range of 930 – 1080 Mpa.

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AISI 4340 steel is a medium carbon, low alloy steel known for its toughness and strength in relatively large sections. AISI 4340 is also one kind of nickel chromium molybdenum steels. 4340 alloy steel is generally supplied hardened and tempered in the tensile range of 930 – 1080 Mpa. Pre hardened and tempered 4340 steels can be further surface hardened by flame or induction hardening and by nitriding. The 4340 steel has good shock and impact resistance as well as wear and abrasion resistance in the hardened condition. AISI 4340 steel properties offer good ductility in the annealed condition, allowing it to be bent or formed. Fusion and resistance welding is also possible with our 4340 alloy steel. ASTM 4340 material is often utilized where other alloy steels do not have the hardenability to give the strength required. For highly stressed parts it is excellent choice. AISI 4340 alloy steel can also be machined by all customary methods.

Due to availability the ASTM 4340 grade steel is often substituted with European based standards 817M40/EN24 and 1.6511/36CrNiMo4 or Japan based SNCM439 steel. You have the detailed data of 4340 steel below.

1. AISI Alloy 4340 Steel Supply Range

4340 Steel Round Bar: diameter 8mm – 3000mm (*Dia30-240mm in stock in annealed condition, immediate shipment)

4340 Steel Plate: thickness 10mm – 1500mm x width 200mm – 3000mm

4340 Steel Grade Square: 20mm – 500mm

Surface Finish: Black, Rough Machined, Turned or as per given requirements.

Technical data

2. AISI 4340 Steel Specification and Relevant 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

3. ASTM 4340 Steels And Equilvalents 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

4. AISI Alloy 4340 Steel Mechanical Properties

Mechannical Properties (Heat Treated Condition )	Condition	Ruling section mm	Tensile Strength MPa	Yield Strength MPa	Elong. %	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 (20°C/68°F, specimen oil hardened, 600°C (1110°F) temper	12.3 µm/m°C	6.83 µin/in°F
Thermal conductivity (typical steel)	44.5 W/mK	309 BTU in/hr.ft².°F

5. Forging of 4340 Alloy Steel

Preheat the steel 4340 first, heat up to 1150°C – 1200°C maximum for forging, hold until temperature is uniform throughout the section.

Do not forge below 850 °C. 4340 has good forging characteristics but care must be taken when cooling as the steel shows susceptibility to cracking. Following forging operation the work piece should be cooled as slowly as possible. And cooling in in sand or dry lime is recommended etc.

6. AISI 4340 Steel Grade Heat Treatment

Stress Relieving

For pre-hardened steel stress relieving is achieved by heating steel 4340 to between 500 to 550°C. Heat to 600 °C – 650 °C, hold until temperature is uniform throughout the section, soak for 1 hour per 25 mm section, and cool in still air.

Annealing

A full anneal may be done 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). From 315°C 600 F it may be air cooled.

Tempering

AISI 4340 alloy steel should be in the heat treated or normalized and heat treated condition before tempering. The tempering temperature for depends upon the strength level desired. For strength levels in the 260 – 280 ksi range temper at 232°C (450 F). For strength in the 125 – 200 ksi range temper at 510°C (950 F). And don’t temper the 4340 steels if it is in the 220 – 260 ksi strength range as tempering can result in degradation of impact resistance for this level of strength.

Tempering should be avoided if possible within the range 250 °C – 450 °C due to temper brittleness.

Flame or Induction Hardening

As mentioned above, pre-hardened and tempered 4340 steel bars or plates can be further surface hardened by either the flame or induction hardening methods resulting in a case hardness in excess of Rc 50. AISI 4340 steel parts should be heated as quickly as possible to the austenitic temperature range (830 °C – 860 °C) and required case depth followed by an immediate oil or water quenching, depending upon hardness required, workpiece size/shape and quenching arrangements.

Following quenching to hand warm, tempering at 150°C – 200°C will reduce stresses in the case with minimal effect on its hardness.

All de-carburised surface material must first be removed to ensure best results.

Nitriding

Hardened and tempered 4340 alloy steel can also be nitrided, giving a surface hardness of up to Rc 60. Heat to 500°C – 530°C and hold for sufficient time (from 10 to 60 hours) to develop the depth of case. Nitriding should be followed by slow cooling (no quench) reducing the problem of distortion. The nitrided grade 4340 materials can therefore be machined to near final size, leaving a small grinding allowance only. The tensile strength of the 4340 steel material core is usually not affected since the nitriding temperature range is generally below the original tempering temperature employed.

Surface hardness achievable is 600 to 650HV.

7. Machinability

Machining is best done with the alloy steel 4340 in the annealed or normalized and tempered condition. It can be readily machined by all conventional methods such as sawing, turning, drilling etc. However in the high strength conditions of 200 ksi or greater the machinability is only from 25% to 10% that of the alloy in the annealed condition.

8. Welding

Welding of steel 4340 in the hardened and tempered condition (as normally supplied), is not recommended and should be avoided if at all possible, because of the danger of quench cracking, as the mechanical properties will be altered within the weld heat affected zone.

If welding must be carried out, pre-heat to 200 to 300°C and maintain this while welding. Immediately after welding stress relieve at 550 to 650°C, prior to hardening and tempering.

If welding in the hardened and tempered condition is really necessary, then the work piece, immediately on cooling to hand warm, should be if possible stress relieved at 15 °C below the original tempering temperature.

9. Application of 4340 Steel

AISI 4340 steel is used in most industry sectors for applications requiring higher tensile/yield strength than 4140 steel can provide.

Some typical applications such as:

Aircraft Landing Gear
Automotive,
Oil and Gas Drilling,
Forging,
Warm and Cold Forming,
Machine Building,
Transfer Systems, like power transmission gears and shafts.
General engineering industries and structural use applications, such as: heavy duty shafts, gears, axles, spindles, couplings, pins, chucks, molds etc.

is one of leading supplier of AISI 4340 steel for your different application as above. And we supply 4140 steel, 4130 steels as well. Contact me and let me know your requests anytime.

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The group company and factory cover an area of more than 800 mu, with more than 1,500 employees, and its business covers more than 20 countries and regions around the world. Xinghan Group is committed to developing new types of steel products and building a first-class coated sheet and steel manufacturing enterprise with international competitiveness. Xinghan Group hopes to grow into a widely respected and sustainable global resource-based enterprise through continuous pursuit of excellence, create better social, economic and environmental benefits, and bring more competitive value returns to employees and customers.

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The company has major production lines such as pickling, cold rolling, hot dip galvanizing, hot dip galvanizing, thick plate galvanizing and color coating, forming an annual production capacity of 1 million tons of pickling coil, 1 million tons of cold rolled sheet and 900,000 tons of hot dip galvanized sheet. Galvanized and hot-dip galvanized aluminum zinc silicon steel sheet scale 450,000 tons thick galvanized steel plate scale 300,000 tons color coated steel plate scale is one of the largest steel and non-ferrous metal smelting and processing suppliers in Shandong Province.

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The company adheres to the development strategy of "seeking development by science and technology, seeking efficiency by management", adheres to the core values of "people-oriented, integrity, responsibility and excellence", adheres to the development system of "green products and green industry", "promotes high-quality beyond development in an all-round way", and realizes the vision of "building a first-class aluminum processing service enterprise with international competitiveness".

Application field

The main supply fields are: aerospace, national defense equipment, military weapons, chemical industry, shipbuilding, nuclear energy, trains, containers, environmental protection, precision machining, auto parts, machinery, electronic products, molds, medical treatment Equipment, construction, decoration, etc.

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FAQ

Q:How long is your delivery time?

A:Within 5 days for stock size, 15-30 days for customized size.

Q:How can I get an accurate quote?

A:Please provide the information of prodcuts standard, material, size and quantity.

Q:When can I get your reply after the inquiry.

A:Within 15 minutes during working time, whthin 12 hours during non-working time.

Q:What product information do I need to provide?

A:You need to provide the grade, width, thickness,coating and the number of tons you need to purchase.

Q:Can you provide sample ?

A: We can provide the samll samples in stock for free, as long as you contact us. Customized samples will take about 5-7days.

Q:How many coutries you already exported ?

A: Exported to more than 50 countries mainly from America, Russia, UK, Kuwait, Egypt, Turkey, Jordan,India, etc.

Q: Can we visit your factory?

A: Sure, we welcome you to visit our factory , check our production lines and know more about our strength and quality.

Q:Can you send samples?

A:Of course, we can send samples to all parts of the world, our samples are free, but customers need to bear the courier costs.

Steel Round Bars