UNDERSTANDING STEELS: WHAT IS A 4340 STEEL?

The AISI 4340 steel is a type of steel that has molybdenum, chromium, and nickel alloys.

Image of how AISI 4340 steels look like

You probably know them because of their ability and their high strengths. But as you may have noticed, alloys and steels are distinguished by numbers – do you know what these numbers mean?

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

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

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

WHY IS IT “4340?”

In the SAE and AISI numbering system, the first (1^st) digit of the steel represents the category where the metal belongs.

1 is for carbon steels, 2 is for nickel steels, and so on. The number four (4) indicates that a steel is a type of molybdenum steels.

Then, the second (2^nd) number represents the existence of major elements. These major elements would affect and modify the properties and the overall characteristics of the steel.

In the case of 4340, it means that three (3) elements are present, and they include nickel, chromium, and molybdenum.

Lastly, the ending digits or the final two (2) digits represent the carbon concentration level at 0.01%. Therefore, in the case of 4340, the carbon content in it is 0.40%.

That’s it! That’s what the AISI 4340 steel means and that is how it’s different from other steels!

SAE 4340 steel is a high-strength alloy steel that is frequently used in the aerospace industry. It is known for its excellent toughness and strength-to-weight ratio. In addition, SAE 4340 steel has good ductility, making it suitable for a wide range of applications. This type of steel is often used in the construction of aircraft parts and other critical components.

WHAT IS 4340 STEEL PROPERTIES?

4340 steel is a chromium-molybdenum alloy steel that provides excellent tensile and impact strength. The addition of molybdenum gives 4340 superior strength over other steel grades, while the chromium adds enhanced hardenability, abrasion resistance, and wear resistance.

4340 can be heat treated to achieve a wide range of mechanical properties, and is often used in applications that require high strength and toughness.

4340 is available in a variety of sizes and shapes, making it an excellent choice for a wide range of applications. Contact your local metal supplier for more information on 4340 steel properties and availability.

WHAT IS THE HARDNESS LEVEL OF 4340 STEEL?

Since 4340 steel is known for its toughness, you can expect to receive surface hardness levels that can go as high as HRC 62 or 600 to 650 HB.

4340 steels are hard, therefore you can use it for a wide range of applications

This level of hardness is already effective if you’re going to produce blades, knives, and other multi-purpose tools.

AT WHAT POINT OF TEMPERATURE DOES AISI 4340 MELT?

The melting point of the AISI 4340 steel is at 1,427 degrees Celsius or about 2,600 degrees Fahrenheit.

Therefore, if you’re requiring temperatures that go above these, 4340 steel might not be the best option for you as they can melt.

IS AISI 4340 STEEL A TYPE OF STAINLESS STEEL?

AISI 4340 is a type of molybdenum steel that contains a significant amount of Chromium.

You can consider 4340 steel as a type of stainless steel

And since Chromium is what makes steel stainless, then therefore, we can come up to a conclusion that AISI 4340 steel is stainless

WHAT IS THE DIFFERENCE BETWEEN 4140 AND 4340 STEELS?

4340 and 4140 steels are two (2) of the most common grades of steel. They’re used for varying types of applications and are applied to multiple businesses and industries across the globe.

But, how do they differ? What makes AISI 4340 and 4140 steels different? Now that we know what these numbers really mean, it’s easy for us to identify and separate 4340 from 4140.

Chemical Composition

While both steels have the same level of carbon, they differ on the composition of elements and chemicals.

For instance, 4140 does not contain nickel, while 4340 contains about 1.82% of nickel, which is already considered high.

Applications

Because of its flexibility and versatility, AISI 4140 steel is a type of steel that’s usually used in the aviation, space, and defense (ASD) industries. Not only that, you can also find use of it in the automotive, oil and gas industry, as well as the agriculture industry.

The 4340 steel, on the other hand, is mainly used in heavy-duty applications such as high stress and high impact situations, transmission parts, engines and rotors, and so on.

Properties

AISI 4340 steel is finished via quenching and tempering, therefore, you can consider it to belong on medium-quality carbon. 4140 steel, on the other hand, is famous for its ability to resist corrosion, considerate levels of strength, and its ability to resist wear and abrasion.

WHAT ARE THE APPLICATIONS OF 4340 STEEL?

The “almost” perfect balance of strength/toughness and malleability that AISI 4340 steel provides enables it to be one of the best types of steel you can use in creating engines, gun parts, gears, etc.

WHAT KIND OF STEEL IS 4340?

4340 is a steel type that has medium carbon and low alloy steel levels. This particular grade is popular due to the balance that it has in terms of strength and toughness.

You usually get supplied with 4340 steel in the tempered and the hardened condition. This makes the tensile strength range from 930 and 1,080 MPa.

INDUSTRIES THAT UTILIZE 4340 STEEL

There’s a bunch of business sectors and industries that find themselves the need to use 4340 alloy steels.

Here are the most common of these industries:

• Automotive or Aerospace Industry
• Machine or Equipment Building
• General Engineering Industry
• Transfer Systems
• Forging, Welding, and Machining
• Oil and Gas
• And Many More!

WHATS BETTER 4140 OR 4340?

4340 steel is an alloy steel that is often used in engineering applications. It is a high-strength material that can be heat treated to achieve a desired hardness. 4340 steel also has good toughness and ductility properties. 4140 steel is another alloy steel that lends itself well to engineering applications. It is also a high-strength material, but it has different microstructure compared to 4340 steel. As a result, 4140 steel typically has better wear resistance and abrasion resistance. It is important to choose the right steel for the application, and 4340 or 4140 may be the best choice depending on the specific needs.

IS 4340 A TOOL STEEL?

4340 is a tool steel that is prized for its toughness and high strength. It has excellent cutting and machining properties, making it well-suited for a wide range of applications. 4340 is often used in the aerospace, automotive, and construction industries. It can also be used for a variety of other purposes, such as injection molding and die casting. 4340 is an alloy steel that contains chromium, molybdenum, and nickel. These elements give 4340 its excellent strength and toughness. 4340 can be heat treated to various levels of hardness, making it suitable for a wide range of applications. 4340 is a versatile tool steel that can be used for a variety of purposes.

WHAT’S THE DIFFERENCE BETWEEN 4130 AND 4340 STEEL?

AISI grades of steel have differing levels of carbon, manganese and silicon to create different attributes in the metal. 4130 contains up 0.28% to 0 .33%, while 4140 has around 75 -100 % more Manganese which produces an alloy with greater hardenability as well as strength properties than its counterpart 11000 series versions at about 20-25%. The Romans were using this type back then but today you will find that most swords are made from softer Aisi 4005 or 42CrMo Steel because they can be easily welded together without having any issues later down match life due too rapid wear rates.

IS 4340 STEEL FORGED?

Yes, it’s a heat-treatable low iron carbon alloy. The purpose for adding elements to this type of metal is so that its properties will be improved over plain steels like chromium or molybdenum which also can improve penetration in some cases when making swords out of high quality steel blades but are not normally used alone because they both lack phosphorus content needed at certain points while melting down liners during forging processes either way there needs more than just one material before anything decent comes up with any meaningfully strong weaponized cutting edge what we’re talking about here involve combinations such as vanadium along side nitrogen and sulfur right.

IS 4340 STEEL GOOD FOR KNIVES?

4340 steel is a type of steel that is perfect for the application where hardness and strength are the most important factors.

WILL 4340 STEEL RUST?

4340 steel is an alloy steel that contains iron, chromium, nickel, and molybdenum. 4340 steel is known for its high strength and toughness. 4340 steel also has excellent weldability properties. 4340 steel can be heat treated to achieve a wide range of mechanical properties. 4340 steel is often used in the aerospace industry for applications such as shafts, gears, and bolts. 4340 steel has good resistance to corrosion. 4340 steel can be exposed to moist environments and still maintain its corrosion resistance. 4340 steel can be used in both salt water and fresh water applications.

CAN YOU WELD 4340 STEEL?

Yes! As a matter of fact, 4340, along with the other members of the Chromium-Nickel-Molybdenum alloy family are weldable in their heat treated stage.

HOW DO YOU HARDEN 4340 STEEL?

Just like different types of steels, the 4340 steel you will get can be hardened through a few different treatment processes and methods.

HOW STRONG IS 4340 STEEL?

Steel strength is the quantitative measurement of the stress that the steel is able to withstand. It can either be from breaking (tensile strength) or deformity (yield strength).

You can simply understand it that when a steel cracks easily, it simply means it has low strength.

WHAT IS THE STRESS RELIEVING PROCESS OF 4340 STEEL?

The stress relieving procedure of pre-hardened 4340 steel can be obtained by heating the steel to about 500 to 550 degrees Celsius.

WHAT HARDNESS CAN YOU ACHIEVE BY NITRIDING 4340 STEEL?

Should you be unaware of what nitriding is, it is the procedure of subjecting steel to heat with nitrogenous materials such as ammonia. What this does is it increases both the corrosion resistance and the hardness of the steel.

Nitriding 4340 steel can actually help you get 600 to about 650 HV in the hardness scale.

CAN YOU WELD STRESS PROOF STEEL?

Stress proof steel is a type of steel that has medium carbon levels and free-machining capabilities that have been subject into cold reduction.

FORGING OF 4340 STEEL

When it comes to the forging or the creation of 4340 steels, the base steel needs to be pre-heated at about 1,150 degrees Celsius up to 1,200 degrees Celsius.

That’s the temperature that’s the best for forging, and it has to be held until the temperature’s uniform across the entire part of the steel.

WARNING: Refrain from forging below 850 degrees Celsius because the characteristics and the traits need to always be taken care of.

SHOULD YOU COOL 4340 STEEL IN AIR?

The best and the most recommended cooling after the forging is to cool them in dry lime or in sand.

This is so that the steel wouldn’t be susceptible to cracking, being damaged, and the like.

IS 4340 STEEL CORROSION RESISTANT?

The corrosion resistance of steel is determined by the amount of chromium content present.

4340 steel boasts of chromium content that ranges from a minimum of 0.6 up to 1.40%. Its corrosion resistance capabilities are pretty decent, but, it’s not the best. What’s still the best are stainless steels since they have 10% and above levels of chromium.

That brings us to our next question, which is…

IS 4340 A STAINLESS STEEL?

No, 4340 is not a type or a classification of stainless steel. Instead, it is a type of alloy steel since it contains various alloying elements.

Stainless steels in different forms and shapes

A steel will only be known and classified as stainless steel if its chromium levels are 10.5% and above.

WHAT IS 300M STEEL?

300M steel is a type of vacuum melted, low alloy steel that contains high levels of strength.

Sample image of 300M steels

The reason it’s overly connected with 4340 steel is because of the fact that it’s a modification of the AISI 4340 steel.

300M is a steel type that contains added alloying elements of vanadium and silicon, with additional molybdenum and carbon content.

This particular steel boasts of the good strength combination it has that is within the ranges of 1,930 to 2,100 MPa.

HOW HARD CAN MILD STEEL GET?

Only Ferritic stainless steels are the types of steels that aren’t capable of being hardened by heat treatment.

Ideally, mild steels that have been carburized would have a soft core with a supremely hardened surface. What this basically means is that the low carbon content of the exterior would cover up the core that’s not that hard or tough.

Generally, though, mild steel can only go up to about 35 to 40 HRC at the maximum.

WHAT IS THE MACHINABILITY OF 4340 STEEL?

The rate or the level of machinability of the 4340 steel is actually one of the best. Because of the fact that it contains low carbon levels, it’s not as stiff as those steels that have higher carbon contents.

In almost all situations, though, machining or forming 4340 steels would have to be under certain adjustments. This is for the material to have an assured shape or form instead of having a “forced” look type of feel.

CAN YOU HEAT TREAT 4340?

4340 steel is a high-strength alloy that can be heat treated to provide superior toughness and strength. The alloy has excellent hardenability and can be quenched and tempered to achieve a wide range of mechanical properties. 4340 steel is often used in applications requiring high strength and toughness, such as gears, shafts, and connecting rods. The steel can also be welded, making it an ideal choice for fabrication and repairs. 4340 steel can be heat treated using a variety of methods, depending on the desired properties. For example, 4340 steel can be austenitized at 870-900°C followed by oil or water quenching. This will result in a microstructure of fine martensite with excellent strength and toughness. 4340 steel can also be carburized to achieve even higher levels of strength and hardness. When carburized, 4340 steel is typically heated to 900-940°C in the presence of carbon-bearing gases. This process diffuses carbon into the surface of the steel, increasing the hardness and strength of the alloy. Carburized 4340 steel is often used in applications that require extremely high levels of strength, such as gears and shafts for high-performance engines.

4340 STEEL EQUIVALENTS

Akin to other grade of steel, 4340 steels have equivalents in other standards. You have to take note, though, that just because they’re labeled as “equivalents,” they don’t contain the exact amounts or content levels of each alloying element.

The equivalents of 4340 steels include:

• 41NiCrMo7-3-2
• DIN 1.6563
• SNCM439
• 36CrNiMo4

4340 STEELS SUPPLY FORMS

You can purchase 4340 steels in round bars, plates, sheets, square bars, hexagonal bars, and the like.

However, you also have the option to have them customized depending on whatever your needs are!  

4340 STEEL BAR

4340 steel bar is a type of steel that contains chromium, molybdenum and manganese. It is a durable alloy that is often used in high-strength applications. 4340 steel bar has a high toughness and tensile strength, making it ideal for use in shafts, gears and other critical components. 4340 steel bar is also resistant to wear and corrosion, making it an ideal choice for use in industrial applications. 4340 steel bar is available in a wide range of sizes and shapes, making it easy to find the right option for your needs. 4340 steel bar is an excellent choice for applications requiring high strength and durability.

4340 STEEL ALLOY PLATE

4340 steel alloy plate is a high strength alloy that exhibits excellent toughness and ductility. It is used in a variety of industries due to its good balance of strength, toughness, and wear resistance. 4340 steel alloy plate can be heat treated to a wide range of properties, making it an ideal choice for many applications. The high strength and toughness of 4340 steel alloy plate make it an excellent choice for use in structural applications, such as in automotive and aerospace industries. 4340 steel alloy plate is also commonly used in applications where wear resistance is important, such as in the mining and oil and gas industries. 4340 steel alloy plate is available in a variety of sizes and thicknesses to meet the requirements of any application.

4340 STEEL ROD

4340 steel rod is a high-strength alloy that is often used in applications that require high levels of strength and toughness. The alloy is composed of iron, carbon, manganese, chromium, and molybdenum, and it offers excellent levels of strength and hardness. 4340 steel rod is often used in the construction of shafts, gears, and other parts that are subject to high levels of stress. In addition, 4340 steel rod can also be used for making fasteners and other types of components that need to resist wear and tear. Thanks to its combination of strength and toughness, 4340 steel rod is an essential material for many industries.

4340 STEEL FORGINGS

WALDUN/4340 steel forgings are a versatile and strong choice for use in a variety of applications. The forgings are made from 4340 steel, which is known for its strength and durability. 4340 steel is an excellent choice for parts that will be subject to wear and tear, as it is able to withstand high stress and heavy loads. The weldability properties of 4340 steel make it easy to join together with other materials, making it a versatile choice for use in a wide range of applications. WALDUN/4340 steel forgings are available in a variety of shapes and sizes, making them suitable for use in the automotive, aerospace, and defense industries.

DO MANUFACTURERS ANNEAL AND TEMPER 4340 STEELS?

Yes, AISI 4340 steels can be annealed and tempered; it can be your choice, too.

You can choose to anneal it so that the steel becomes more eligible and applicable for machining. The usual annealing temperature you can get with it is at 1,525 degrees Fahrenheit or 830 degrees Celsius to 1,350 degrees Fahrenheit or 730 degrees Celsius.

Tempering, on the other hand, is best if you want your 4340 steel free from all the stress. In addition to that, you can also choose to temper it so that it can achieve some mechanical properties.

WHO IS THE BEST 4340 STEEL MANUFACTURER IN THE MARKET?

If you’re looking to work with a Chinese 4340 steel manufacturer, don’t hesitate to give Waldun Steel a call. Across the entire country, we’re the best because of the certifications and the awards we’ve received.

As a matter of fact, you can trust us if you need pre-made or custom 4340 and 4140 steels! We have a Research and Development (R&D) team that’s always open and willing to help and to assist you with what you need!

CAN YOU GET A SAMPLE OF THE 4340 STEEL YOU’LL PURCHASE?

Absolutely! You can get a free sample of the AISI 4340 steel that you would purchase from us! It’s just one way of us proving to you that our goal and our mission is to provide quality products!