Stainless steel is an alloy of Iron with a minimum of 10.5% Chromium. Chromium produces a thin layer of oxide on the surface of the steel known as the “passive layer”. This prevents any further corrosion of the surface. Increasing the amount of Chromium gives an increased resistance to corrosion.
Additions of molybdenum also increase corrosion resistance in reducing acids and against pitting attack in chloride solutions. Thus, there are numerous grades of stainless steel with varying chromium and molybdenum contents to suit the environment the alloy must endure. Stainless steel’s resistance to corrosion and staining, low maintenance, and gorgeous lustre make it an ideal material for many applications where both the strength of steel and corrosion resistance are required.
Yes, stainless steel is “stain-less” not “stain-impossible”. Stainless steel knives can in some circumstances rust but they are much more resistant to corrosion than ordinary carbon or alloy steels.
The Rockwell scale (aka HRC) is a standard to compare the hardness of steels. It measures hardness based on the depth of penetration of a diamond cone pressed into the material at a constant pressure. In short, the higher the number, the harder the steel.
In general, SHAN ZU GYO Series and SHAN ZU PRO Series made of premium Japanese steel with 60-62HRC, SHAN ZU Elite Series made of 9Cr18MoV steel with 57-59HRC, and SHAN ZU Classic Series made of X50CrMoV15 with 55-57HRC. An increase of 1 degree Rockwell equates to an increase in hardness of about 10% as well as an increase in edge-holding ability. These degrees of hardness enable SHAN ZU knives to be thin and sharp without being overly brittle.
9Cr18MoV and X50CrMoV15 are two different types of premium steels that SHAN ZU uses to make our blades. They differ in the compositions like C, Cr, Mo, V.
9Cr18MoV is highly refined high carbon stainless steels with excellent hardness, edge retention and durability.
X50CrMoV15 contains less carbon than the other two so it has better weldability and rust resistance.