Steel Quality

I've taken this article from a newspaper because it gives a fairly accurate but still straight-forward discussion of steel quality. The critical point that I would like to emphasize from this article is that 440C steel is not an alloy designed for sword blades however well it may hold an edge. As a mass produced and readily available material it is a less expensive choice than some alternatives designed for sword construction while having many benefits over lesser alloys. Many manufacturers use this alloy for their swords, so this article just provides a simple perspective to some of the possibilities.

The article is published in unedited form until I'm able to get permission from Mr. Lipinski to extract the pieces of immediate interest to swordsmen.

By Edward R. Lipinski

In order to understand tool quality, one should have some understanding of steel. Steel is basically an alloy of iron and carbon. More specifically, it is iron that has a carbon content of 1.7 percent or less. The addition of carbon makes the metal harder, but also more brittle, less malleable and less able to withstand stress and shock.

Manufacturers recognize that different tools are subjected to different amounts of stress and shock, so they match steel with a suitable carbon content for each tool. Too-quality steel must have at least 0.6 percent carbon content. This relatively small amount of carbon insures that the steel can be heat treated.

The traditional method of heat treating involves heating the metal to a temperature of about 1,350 degrees Farenheit then plunging it in to cool water. This abrupt cooling techinique, called quenching, changes the carbon particles in the metal into hard carbide crystals. Heat treating produces a hard edge on tools. Unfortunately, however, it only penetrates about 1/8" into the metal and thick tools retain a soft center. This happens because the outside edge of the metal comes in contact with the water while the core remains relatively insulated. It cools at a much slower rate and the carbon is not able to crystallize.

Ancient metal smiths realized that tools or weapons would be more durable if the hard shell could somehow be inserted in the core of the metal. In Damascus they hit upon the technique of folding the metal again and again, then hammering it into a solid piece of laminated steel. This technique was so successful that Damascus steel became prized throughout the ancient world.

The lamination technique was also perfected in Japan; artisans used it to manufacture samurai swords. This method of tool making continues today in Japan. In the United States, it is used by artisans who specialize in creating custom-made knives.

The Damascus process took time. Each piece had to be tested for quality and there were many rejects. The process was eventually abandoned for a less complicated technique. The Smith shaped the tool, heated it in the forge, then quenched it. By carefully limiting the thickness of the tool, the blacksmith could fashion a tool with the right combination of toughness and hardness.

Obviously, the quality of each tooll varied with the skill of the smith, but many blacksmiths were able to make quality tools that are still in use today. They were made from carbon steel and were called "water-hardened steel" tools. The were, and still are, prized for their ability to hold a keen edge. These tools have two serious drawbacks, however. They tend to rust easily, and they can lose their temper and edge when subjected to high temperatures.

These are not serious problems for hand tools created for normal woodworking tasks, but in power situations the tools do not hold up. For example, carbon-steel drill bits will dull quickly when used in an electric drill, and a carbon-steel turning chisel, for use on a lathe, will lose its edge when subjected to the friction of the rotating wood.

In an effort to make better steel, metallurgists experimented by adding other ingredients to make superiour alloys. For example, they added tungsten or molybdenum to create high-speed steel. These tools can withstand the heat buildup created in power jogs. When buying drill bits, be sure to look for ones made of high-speed steel.

Chromium and nickel are added to make stainless steel. Stainless steel is virtually rust-proof. Early stainless steel knives had one major drawback however, they could not hold a sharp edge the way carbon steel knives could. Chefs and serious cooks preferred carbon steel knives (even though they were prone to rusting) for this reason. Metallurgists gradually improved the quality of stainless steel and they developed a grade for cutlery (called 440C) that is rust resistant and can hold a keen edge.

In addition to creating alloys, manufactuerers also improved the techniques of steel making. They developed special heat-treating ovens and slow-quenching methods so that temper and hardness could be accurately controlled.

Are modern tools superior to those of past generations? In general yes, but there are exceptions. Many hardware stores and home centers offer cheam, bargain-basement tools for only a few dollars. Other cheap tools are case-hardened so that the hard exterior is only a fraction of an inch thick. When the tool is charpened, the hard exterior is ground off; the tool cannot hold an edge. Some of these tools look like stainless steel, but they are only nickel-plated. As soon as the plating wears off, the tool begins to rust.

You get what you pay for. When it comes to tools, it pays to buy good quality produects made by a reputable manufacterer


For more information email the Ring of Steel at rosteel@umich.edu	Web space provided by Deathstar.org