440a stainless steel is a type of steel that has increased corrosion resistance. This blog post will explore the properties, uses, and production methods of 440a stainless steel.
What is 440a Stainless Steel?
440a Stainless steel is a medium carbon, martensitic stainless steel with a range of applications in knives, and surgical tools. High chromium resistance is expected from this grade because of its 17% chromium content.
440a Steel Composition
| Elements | Wt% |
|---|---|
| Carbon | 0.60-0.75 |
| Chromium | 16.0-18.0 |
| Molybdenum | 0.75 |
| Nickel | 0.5 |
| Manganese | 1 |
| Silicon | 1 |
| Phosphorus | 0.04 |
| Sulfur | 0.03 |
What is the hardness of 440a Steel?
440A stainless steel has a Rockwell hardness of 55-58 HRC.
This makes it easy to machine and sharpen, though less durable than 440B or 440C steels because they contain more caron.
440a Steel Properties
Mechanical Properties Chart
| 1080 Mech Properties | As Rolled |
|---|---|
| Hardness, Rockwell B | 95 |
| Tensile Strength, Ultimate | 725 - 1790 MPa |
| Tensile Strength, Yield | 415 - 1650 MPa |
| Elongation at Break | 5.0 - 20 % |
| Modulus of Elasticity | 204 - 215 GPa |
| Bulk Modulus | 166 GPa |
| Poissons Ratio | 0.283 |
| Shear Modulus | 83.9 GPa |
Thermal Properties Chart
| 1080 steel | Thermal Properties in Metric Unit |
|---|---|
| Coefficient of Thermal Expansion | 10.2 µm/m-°C |
| Specific Heat Capacity | 0.460 J/g-°C |
| Thermal Conductivity | 24.2 W/m-K |
Wear Resistance
This steel is a good option for people who are looking to have an everyday knife but don’t want it wearing down easily.
The wear resistance of this type of steel isn’t the best though; because 440A leans towards softer steels than harder ones, you shouldn’t use your knives in ways that might deform them over time.
Overall, this steel is great for camping purposes and its wear resistance is enough to handle your routine tasks with ease.
Edge Retention
The carbon in the 440A steel makes this knife moderately hard.
This quality enables it to keep its cutting edge for longer though less so than other steels due to their increased volume of carbon and hardness, such as the 440B or C knives which will offer better edge retention.
Edge retention is mainly linked to steel hardness and, with moderate hardness, edge retention is up to the level that It can be comfortably used for routine camping or kitchen tasks for a long time.
Check hardness of steel with Vicker, Rockwell or Brinell Hardness Tester.
Steel Toughness
A fair amount of toughness with 440a stainless steel makes it a great choice for knives that won’t chip or break easily under lateral pressure.
The Manganese and Nickel in this grade work together to provide you the desired level of resistance against chipping, breaking or bending while still giving your blade decent wear resistance.
This type is also referred as “stainless alloy cutlery steels” because they are perfect for high-quality kitchen utensils like steak knives which need only modestly levels on all types of durability features combined into one single product.
Toughness has a direct relationship with ductility. Normally steel which are tougher usually have great ductility. You can identify the ductility of materials with Erichsen Cupping Test.
This steel might not be the toughest grade available but you got to appreciate that it delivers a fair amount of toughness and won’t chip or break easily under lateral pressure.
Corrosion Resistance
440a steel is one of the most corrosion-resistant types. It even beats its siblings that rely on higher carbon content for their strength and resistance to rusting or staining. T
his type of knife will never be easily affected by dirt, grime, mud or other outdoor elements because it does not corrode as quickly due to lower carbon levels.
This stainless-steel knife is ideal for camping and outdoor activities compared to others grades in 400 series iron alloys where more carbon makes them harder but also easier prey for stains and unwanted oxidation.
Corrosion resistance plays a great role and that effect can be seen in 1095 steel and 1095 cro van steel. With little addition of chromium, 1095 cro van steel offers optimum properties as blade steel as compared to 1095.
Ease of Sharpening
When the hardness of steel goes below 55 HRC, it is called soft. 440A stainless which has a hardness rating of 54-58 HRC falls under this category and hence sharpening such knives do not require high-end diamond abrasives. This property makes them easier to sharpen as compared to other hard steels with ratings above 58HRC.
Resilience
Resilience has to do with the amount of non-permanent deformation an object can withstand without breaking. The material’s modulus of elasticity is a good indicator for its resilience, as well as low strain and high yield stress.
As given in the chart above, you can see 440a steel will have sufficient resilience and low fracture toughness.
Impact Resistance
440a stainless steel, which is low in impact resistance, has high hardness. This can be explained by factors such as how materials perform under extreme conditions like strain rate or pressure and the fact that most alloy steels with high hardness are also usually low in impact resistance.
High-Temperature Resistance
As 440a steel becomes softens during heating, it is always recommended for designers to consider this condition before deciding on manufacturing products out of it.
The reason for softening is in the tempering of steel. All alloy steel soften during the heating process and the same goes for 440a steel.
Heat Treatment of 440a Stainless Steel
The common heat treatment applied on 440a steels include annealing and hardening tempering and welding is also accompanied by post and pre weld heat treatments.
ANNEALING
To fully anneal 440a steel heat to 840/870˚C soak for required time according to the thickness and slowly cool slowly cool it to about 600°C in furnace then air cool.
For complete information on annealing, checkout detailed article on Annealing of Steel.
They can be process anneal or intermediate anneal by heating to 730/760˚C followed by air or furnace cool.
HARDENING
Preheat to 1400/1500ºF () – then heat to 1850/1950ºF () – soak and quench in warm oil, or air cool.
To achieve maximum hardness, hardening treatment can be performed on these allows. As they absorb heat slowly, so heat them gradually with a slow ramp rate and keep at that temperature to achieve uniform temperature along with the thickness. These alloys are hardened by slowly heating to a temperature 1010/1065˚C, soaked according to the thickness, and then quenched in oil to room temperature. Thin sections can be cooled in the air rather than oil. A preheating at 760/815˚C is recommended before hardening treatment.
TEMPERING
The hardening treatment is followed by tempering or stress relief treatment at 204-260°C. The maximum hardness of these alloys of around 56/57 HRC can be achieved by tempering at 150/175˚C for one hour.
MACHINABILITY
These alloys are machined in fully annealed conditions using a carbide or ceramic tool.
WELDABILITY
Welding of these alloys is not very common. But if welded, pre and post-welding heat treatment is mandatory. Typically, pre-weld heat treatment involves heating to 260˚C, then welded. An average six hours of annealing at 730/760˚C followed by furnace cool below 260˚C is performed after welding.
Is 440a Steel Good for knives?
A knife made of 440a steel is great for kitchen knives and camping knives because it has excellent corrosion resistance. It also boasts a high hardness, at 58hrc, which makes hunting less difficult as the blade won’t dull easily.
However, this alloy does not have good wear resistance or edge retention so your blades will need sharpening more often than those that are made from other steels on the market. So, hunting with a knife may become easier but regular sharpening will dull your hunting experience.
It is the best recommendation to avoid using 440a stainless steel knives for hunting.
Best 440a steel knives
PUMA Sergeant Pocket Folding Knife
The PUMA Sergeant knife is a great everyday carry pocket folding knife. Its hollow-ground style blade makes it ideal for camp chores, and the 3.1-inch length and 1/8 inch thick blade make it perfect for most cutting tasks.
The German-made 440A steel with a hardness of 55-57 HRC makes the knife durable enough to handle even tough jobs. Total weight of 4.2 ounces makes this an easy-to-carry tool in your pocket or backpack wherever you go!
Standard benefits
- The blade is made of 440A steel and has a hardness of 55-57 HRC, making it durable.
- It’s easy to carry at 4.2 ounces.
- Feel confident in your everyday life with this knife on hand.
- You’ll be able to take care of any task you need with ease when you have the PUMA Sergeant Knife
KnifeStyle Japanese Kitchen Folding Knife
The lifestyle Japanese Kitchen Folding Knife is a great camping knife that folds into its own handle. It has a blade made of Aisi 440a steel, which is super sharp and high quality.
The blade length is 5.5 inches when folded and 10 inches when opened up. This knife also comes with a wood handle for comfort and safety while cooking or cutting meats in the kitchen.
It has a lock bar feature so you don’t have to worry about it closing on your fingers!
Standard benefits
- Sharp blade for easy cutting and slicing
- Compact size, perfect for camping and backpacking trips
- Feel like a samurai warrior while cooking your meals
Camillus CamLite Folding Knife
Camillus CamLite Folding Knife is a perfect all-around knife. It’s suitable as a Tactical knife, hunting knife, camping knife, or survival knife.
The blade is made of 440a steel and bonded with carbonitride titanium. This gives ultra strength in comparison to a normal blade. Superior toughness, sharpness, and corrosion resistance.
Have a lock-back facility for safe use and carry it on your belt loop or pocket.
Standard benefits
- Won’t corrode or rust, even after prolonged contact with salt water.
- Extremely sharp and durable.
- You’ll be able to cut through anything with ease.
- Be prepared for any situation
MIKI Pocket Folding Kitchen Knife
The MIKI Pocket Folding Kitchen Knife is a multi-purpose knife that can be used for camping, fishing, hunting, or even in the kitchen.
It has a sharp blade made of 440A steel and comes with a liner lock to keep the blade safely locked when not in use.
The total length of this pocket folding knife is 10 inches with a 5.5-inch closed blade. It weighs only 3 ounces and it is easy to carry around due to its compact size. The handle has been designed ergonomically for comfort and grip while cutting.
Standard benefits
- Sharp blade made of 440A steel
- Liner lock to keep the blade safely locked when not in use.
440a Steel Comparison with other steels
440a Vs 420hc
440a and 420hc, the both, are stainless steels with good corrosion resistance and moderate wear resistance. In between 440a and 420hc, 420hc has a lower carbon and resultantly offers lower wear resistance and edge retention as compared to 440a steel. In the case of toughness and corrosion resistance, both are of the same level.
440a Vs 440c
440 family consists of three grades, i.e. 440a, 440b, and 440c steels. 440c has higher carbon content as compared to the other two grades and that is why this grade offers better hardness and hardenability. Wear resistance and edge retention offered by 440c is also higher as compared to 440a. 440c is the most commonly used grade for knife making out of all 3 grades.
440a Vs 440b
As discussed earlier, 440b has higher carbon content as compared to 440a so this grade offers slightly better hardness and edge retention as compared to 440a.
440a Vs 8cr13mov
8cr13mov steel is Chinese grade stainless steel offering a better package as blade steel as compared to 440a steel. 8cr13mov steel has lower Cr% but it is enough to keep steel corrosion resistance. However, on other hand, alloying elements in 8cr13mov steel offer better edge retention, sharpness, and better wear resistance.
440a Vs d2 steel
D2 steel and 440a steel are from different classes of steel. One is corrosion resistant while the other is not. In terms of hardness and wear resistance, d2 steel is superior to 440a steel.
On the other hand, the corrosion resistance of 440a steel is better than d2 steel. That is why both blade sheets of steel have a different set of applications.
440a Steel Applications
This knife is reliable for kitchen, cutlery, and surgical instruments because it has been made with steel quality that provides both durability and strength.
While 440a steel is excellent for machine shops because of its ease to work with, it also finds a number of other applications in industries that require high corrosion resistance and will not undergo high pressure.
Therefore, this alloy works well when used as components in those areas where good corrosion and moderate strength are required but the application does not need extreme wear resistance.
Following are components and tools where 440a steel finds application;
- Mold and dies
- Valve components
- Instruments/measurement devices
- Textile components
- Ball bearings
- Cutlery
- Bearings
- Gage blocks
- Molds and dies
- Valve components
- Turbine components
- Medical instruments
- Aircraft structural parts
- Knives and measuring instruments
FAQ
Which is better 440A VS 440C?
Due to higher carbon content, the hardness, and wear resistance of 440C is more than 440A, however, its toughness, edge stability, and longevity are compromised as compare to 440A.
What is the difference between 440A and 440C stainless steel?
The carbon content is the main difference between 440A and 440C as 440A has 0.6-0.75% of carbon while 440C has 0.95-1.20% carbon.
Is 440 a good steel?
Yes, 440 is good steel with high hardness accompanied by good toughness and corrosion resistance.
How strong is 440 steel?
440 steel has a Rockwell hardness of 58 and UTS of 1750 MPa, which makes it quite strong steel also considered as higher-end steel.
