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Monday, October 10, 2011

What a Steel! - What do those ingredients mean to me?

In "What a Steel! Part 1" and in future "What a Steel!" posts, I will do my best to accurately list what each steel contains, giving them their characteristics.  In doing so, I won't be listing what each ingredient does each time it is listed, instead I will use this post as a reference and will point each "What a Steel!" post back to this one for reference.  This will allow you, my readers and customers, the ability to better determine how each of the ingredients affect the steel performance, both in a positive and negative manner. 

The one component that remains consistent amongst all steels is iron.  However, iron is not sourced from one or two locations, but multiple locations and from multiple sources.  Iron is inherently a soft metal and is hardened and made usable as a knife blade by the addition of other ingredients, each of which adds and/or detracts a quality or qualities, such a corrosion resistance.
Please feel free to comment on this post as well as any other post.

This post will be updated often as new information becomes available and does not contain all elements used in the production of various types of steel. 

Carbon - C
  • Most common element added to iron.
  • Increases hardness.
  • Increased edge retention.
  • High carbon steels tend to be a bit more resistant to corrosion.
  • According to the American Iron and Steel Institute (AISI), a for a steel to be considered high carbon, it must contain at least 0.3% carbon.  Many high carbon steels used in knife manufacturing hover in the 1.00% area.
Chromium - Cr
  • Added to create stainless steel.
  • A minimum of 10% chromium is required for a steel to be considered stainless according to AISI.
  • When exposed to oxygen, chromium forms a protective barrier to aid in corrosion resistance.
  • Corrosion resistance (rust resistance) is not the same as corrosion proof (rust proof) and most stainless steels will oxidize (corrode) given the ideal conditions.
  • Hardness and toughness also benefit from the addition of chromium.
Copper - Cu
  • Aides in corrosion resistance
Hydrogen - H
  • Used in place of carbon to make H1 stainless steel.
  • Used to partially replace carbon to make X15 stainless steel.
  • H1 stainless steel has shown strong evidence to be the closest to a true "rust proof" stainless steel.
Manganese - Mn
  • Aides in ability to harden and overall hardness
  • Aides in overall toughness.
  • Adds to corrosion resistance
  • Aides in the ability to machine.
Molybdenum - Mo
  • Aides in the ability to harden and in overall hardness.
  • Aides in toughness and corrosion resistance.
  • Helps with the ability to machine.
Nickel - Ni
  • Aides in overall toughness.
  • May aide in corrosion resistance.
  • Necessary ingredient in austenitic (chromium/nickel) stainless steel, which is the most common variety. According to the AISI, this type of stainless steel accounts for approximately 70% of all stainless steel production.
Niobium - Nb
  • Aides in grain production
  • Aides in corrosion resistance
Phosphorous - P
  • Aides in the ability to machine.
  • Aides in the ability to harden.
Silicon - Si
  • Added to metal in the molten state to aide in the removal of gases and oxidation.
  • Aides in overall strength.
Sulfur - S
  • Aides in the ability to machine.
Tungsten - W
  • Aides in toughness and wear resistance.
  • Aides in the ability harden.
Vanadium - V
  • Added to aide in wear resistance and strength.
  • Allows for fine grain production during heat treatment attributing to the overall hardness (HRc) of the finished blade, edge retention and overall sharpness.
  • Toughness also benefits from the addition of vanadium.