What are Alloys? Why do we need them and which ones are the
ones that effect our wood carving tools? These questions provide
the basis of what to look for in steel. First, you need to understand
that steel is primarily iron. Most steels contain more than 90
percent iron and many carbon steels contain more than 99 percent
iron. But all steels contain a second element or alloy know as
carbon. Many other elements are contained in some steels, but
carbon and iron are the only elements that are in all steel. Carbon
is most important in relationship to hardness. Carbon in steel
ranges from just above .3 percent to approximately 2.0 percent,
with most steels falling between .80% and 1.2 %. Steels with the
least amount of carbon are more flexible and ductile and as the
carbon content increases, so does the strength, hardness and brittleness.
You must have .30 % carbon in order to harden steel, but if you
add too much carbon, steel takes on the properties of cast iron.
There are many different categories and types of steel. However, most steels are generally classified as either alloy steels or carbon steels. Alloy steels are usually more expensive and used primarily in special applications. For wood carving tools the simple steels or carbon steels are more advisable. Alloy steels contain other ingredients beside carbon and iron. Most of these are in small amounts, but they can have great effects on the characteristics of steel. There are three key mechanical properties that effect carving tools. These are; hardness, strength and brittleness. They are all linked and when you change one you change them all. This is why you always hear us talk about the compromises and what works best for carving tools. As you know strength and hardness are normally desirable traits whereas brittleness is generally a bad trait. For our purpose, hardness/brittleness is best modified with heat treating and not alloys, but for other specialty steels; this is where the alloys come in. There has been extensive metallurgical research into steels that increase their hardness and strength while not increasing their brittleness. Now keep in mind that strength can refer to many different types: tensile strength, compression strength, shear strength, fatigue strength or endurance, toughness and impact strength to name a few. With wood carving tools we usually refer to the toughness, which is the ability to withstand shock and hardness which refers to the tools ability to hold an edge. The harder the tool the longer it holds an edge. Brittleness is the trait you try to avoid, because it leads to edge chipping. So how do you come up with a happy medium? You need good steel and it must be treated properly. The Heat treating plays a big factor. However, since we are concentrating on alloys lets look at how different alloys effect the physical properties of steel. For wood carving tools you are mainly concerned with the high carbon steels and the alloy steels are usually not of concern. Some of the high carbon steels will have trace amounts of alloys and they do effect the properties, but it is not as crucial as one might think.
Here is a list of some of the more common steel alloys and the effects they have on steel.
|Alloy||Effect of steel|
|Carbon||hardness, strength and wear|
|Manganese||Strength, hardenablility, more response to heat treat|
|Nickel||toughness and strength|
|Tungsten||high temperature, strength|
|Vanadium||Fine grain, toughness|
|Copper||Corrosion resistance, strength|
What's found in our steel?
We use a W1 or W2 high carbon steel. The Carbon content is between .9 and 1.4 and the W-2 contains Vanadium. We have found these to be excellent simple high carbon steels, with proper heat treating you really can't beat the edge holding capabilities of these steels.
Do you know what happens if you add Chromium to your steel?
You get stainless steel- great for resisting rust, but a poor edge holder. It is all relative.....