SHANGHAI UNITE STEEL
One-stop Brand Service Provider For Globle Machinery And Petrochemical Enterprise And Special Steel Distributor.
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INTRODUCTION
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.
APPLICATIONS
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:
-Delivery Conditions:
Cold drawn: 4-100 mm
Peeled: 30-160 mm
Grinded: 4- 600 mm
Turned: 130-1200 mm
Hot rolled: 12-320 mm
Hot forged: 130-1600 mm
-EAF+(ESR) or EAF+LF+VD+(ESR)
-HOT rolled; Cold rolled; Forged; Cold Drawn
-Heat Treatment: Untreated, Annealing, N+T, Q+T
-Smelting: EAF+LF+VD (+ESR)
-Surface Finish: Black, Rough Machined, Peeled, Turned or upon request
-UT 100% passed
-Cutting service provided
-Third Party inspection is acceptable (SGS, BV etc.)
COMMON 4340 STEEL EQUIVALENCY
| Country | USA | Britain | Britain | Japan |
| Standard | ASTM A29 | EN 10250 | BS 970 | JIS G4103 |
| Grades | 4340 | 36CrNiMo4/ 1.6511 | EN24/817M40 | SNCM 439/SNCM8 |
4340 STEEL BAR 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 OF AISI ALLOY 4340 STEEL BAR
| Normalized 4340 | Annealed 4340 | |
| Tensile Strength | 185,500 psi | 108,000 psi |
| Yield Strength | 125,000 psi | 68,500 psi |
| Elongation (2") | 12.2% | 22% |
| Reduction in Area | 36.3% | 49.9% |
| Brinell Hardness | 363 | 217 |
PROCESSING
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.
AISI 4340 Steel Grade Heat Treatment
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.
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.
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.
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.
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.
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.
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.
What we can offer?
-We offer a wide range of steel products in a wide variety of dimensions and executions, according to the common international specifications or customize.
-Machining and heat treatment are available.
-Also, we advise you in choosing the right materials.
Shape Available
Our Advantages
OUR MAIN PRODUCTS ARE LISTED AS BELOW
Notes:
Available Size:
-Round: Dia. 4-1600 mm
-Flat: T. 10-120 mm x W. 60-810 mm
-Block: T. 80-1200 mm x W. 100-1600 mm
PAYMENT AND SHIPPING
1. Both T/T and L/C will be acceptable
2. Trade Terms: FOB, CIF, CFR
3. The delivery will be in 10-15 days if have stock; For customized items, the delivery will be negotiated by both parties
4. Shipping by sea freight from Shanghai Port (PRC) for Bulk orders, by airfreight or express for samples
COMPANY INFORMATION
Shanghai Unite Steel Trading Co., Ltd
We are committed to integrate engineering steel resources in china and serve the global engineering steel market. Our company has more than 15 years of experience in steel researching, production, managing and sales. And our team mostly are based on and worked in national famous steel enterprise.
In the aspect of resources and information, we have established cooperative and stronger relationship with nearly hundred enterprises, either state-owned or private owned in china.
What’s more, we have built long, deep and close business relationship with dozens of steel company, Sharing and holding equities with several steel enterprises. Because of the close cooperation with steel companies and our pioneering spirit, which can ensure us stay at the top competition, and ensure our customers get what they really want!
FAQ
Q: Are you a manufacturer or merely a trader?
A: We are group of companies and owned manufacturer bases and trading company. We specialized in special steel which include alloy structural steel and carbon steel and stainless steel, etc. All material are with high quality and competitive price.
Q: How do you guarantee the quality of your product?
A: Firstly, we can provide the certificates from the third party, such as TUV, CE, if you need. Secondly, we have a complete set of inspection system and every process is checked by QC. Quality is the lifeline of enterprise survival.
Q: Delivery time?
A: We have ready stock for most of material grades in our warehouse. If the material doesn't have stock, the delivery lead time is about 5-30 days after receiving your prepayment or firm order.
Q: What is the payment term?
A: T/T or L/C.
Q: Can we visit your company and factory?
A: Yes, warmly welcome! We can book the hotel for you before you come to China and arrange our driver to our airport to pick you up when you come.