Belonging to 400 family steel, 440A is Martensitic stainless steel characterized by its amazing corrosion resistance, hardness, machinability, and various other properties. While a high 17% chromium content gets it admirable corrosion resistance ability, its 0.7% carbon content contributes to the hardness of 400A steel(55-58 HRC).
The high carbon alloy steel combines a series of chemical compounds making its steel profile a popular choice to industries involved in manufacturing cutlery and pocket knives, surgical tools, scissors among others.
Being relatively affordable steel has earned a large footprint in the global marketplace and comes within the budget of all clases.
Example products made from it: Linder Stag Lock Back Hunting Folding Knife, MIKI Sharp Japanese Kitchen Chef Knife Pocket Folding Petty Knife for Outdoor Camping, SENBON Ultra sharp pocket foldable Japanese peeling knife.
440A Steel – Chemical Composition
0.75 % of Carbon: the high carbon content contributes to its hardness, corrosion/ wear resistance. However, the high amount of carbon conversely deteriorates strength.
18 % of Chromium: Chromium is another powerful contributor that noticeably increases its corrosion and wear resistance ability by preventing them from oxidizing. It also adds to tensile strength and helps retain the evenness of knife blades.
0.6% of Nickel: A unique element that enhances the toughness.
0.75% of Manganese: Again, the high amount of manganese content helps with increased hardness and brittleness.
0.1% of Silicon: Works similar to manganese to increase resistance.
0.04% of Phosphorus: increasing strength.
0.03% of Sulfur: Although the compound is excellent to increase machinability, however, its mix decreases strength.
0.09% of Molybdenum: While it works similar to sulfur to enhance machinability it differentiates in the term that it also adds to the strength of the target steel.
400A Steel – Properties
A special feature of 400A stainless steel is that combined with the vital elements including carbon, manganese, silicon, nickel, chromium, molybdenum, sulfur, etc in different measurements makes it a perfect alloy stainless steel. Added with nitrogen – the chemical blend of it works more effectively to add to the mechanical and corrosion properties of this Martensitic stainless steel.
Edge Retention
The high amount of carbon content is integral that boosts hardness and helps retain the edge. The moderate amount of sulfur and phosphorus reduces brittleness while adding to hardness. 440A has a unique steel profile with decent amounts of carbon mix which has the potential to increase hardness as high as 55-58 HRC if properly heat-treated.
Corrosion Resistance
Perhaps one of the tempting attributes that make 440A steel ideal for making kitchen knives and surgical tools is its high level of corrosion resistance. The higher amount of chromium content helps prevent steel from possible rusting, erosion, or deterioration caused by external factors.
Sharpening
The hardness and toughness both work in combination making the metal easy to sharpening. In addition to, the kind, quantity and grain size of the hard elements including chromium carbide, vanadium carbide, and Cementite aka iron carbide that generates during the heat treatment makes 440A rock solid and reasonably easy to sharpen whenever you are in need.
Tensile Strength
400A stainless steel combines 1% Manganese and 0.5% Nickel that improves the tensile strength of the steel. Tensile strength refers to the resisting power of steel to cracking against tensile stress or lateral pressure.
Hardness
Containing 0.75% Caron, 440A is fairly hard steel. Its carbon helps increasing hardness to 55-58 HRC if properly heat-treated.
Toughness
Again, with a high amount of chromium and nickel mix, 400A has a quite high toughness. The teamwork of toughness and hardness eventually contributes to the metal strength.
Machinability
For those who are not aware of this term should note that machinability is a specialty of metal that determines the easiness at which the substrate can be shaped, cut, or formed to provide the desired level of surface finish. With steady machinability, 400A steel demands minimum power to cut or shape while producing the end product with a smooth surface finish and minimizing breakage of the tool.
A Comparison with 400 B and 400 C
The high carbon alloy 400 series stainless steel is accessible in the market including 400A and its counterparts 400B, 440C, and less known 440F. While all of them are pretty well-known for their accurate stainlessness, 440A is often acknowledged as the best among the category due to its overall steel profile. Just look at this small comparison:
440A is more or less equivalent to 440B with dissimilarity in terms of the carbon content they process. While the carbon mix in 440A is found 0.75%, it varies between 0.75-0.95percent in 400B grade. Thus, although 400B has more hardiness, it has a low-grade metal strength.
Similarly, while 440c steel is known to possess a better edge retention capability, it’s fairly hard to sharpen it compared to 440A due to the difference in their chemical compounds.
It’s the properties of steel that influence the integrity, permanence, and overall functionality of cutlery knife blades.
Considering the overall chemical characteristics, it can be concluded that 440A is fairly a good standard of steel that buyers can rely on while buying kitchen knives or surgical tools, and other outdoor camping uses. Not only is it durable and sturdy though but also has admirable corrosion and wear resistance ability.
Carbon Steel used for Knife making:
1075
sk-5
k390
L6
ATS 34
52100
1055
Stainless steels used for knives:
N690
154CM
SG2
420HC
CPM 20CV
S30V
Victorinox
420j2
VG10
440A
CTS-XHP
AUS-10
9cr18MoV
14c28n
