For example, 4140 is a common chromium-molybdenum steel with 0.40% carbon, which is what the 40 in 4140 indicates.Ĭhromium-vanadium specifically means a family of steel alloys that, when used for hand tools, have a moderate amount of carbon (often around 0.4% to 0.5%), around 1% chromium, around 0.15% - 0.20% vanadium, and a range of other alloying elements. The name given by the Society of Automotive Engineers (SAE) usually follows the pattern 4XXX. Alloys like chromium-molybdenum and chromium-vanadium are more effective than high-carbon steel in achieving these combined properties.Ĭhromium-molybdenum specifically means a family of steel alloys that, when used for hand tools, have a moderate amount of carbon (often around 0.4% to 0.5%), around 1% chromium, around 0.15% to 0.20% molybdenum, and a range of other alloying elements. WHAT STEEL SHOULD HAND TOOLS BE MADE OUT OF?Īlthough high-carbon steel may be appropriate for hand tools whose main requirement is a hard surface like some blades, most hand tools benefit from a combination of hardness, toughness, and corrosion resistance. Vanadium: increases toughness at high strength reduces grain sizes. Nickel: increases toughness at high strength. Molybdenum: makes steel stronger, harder, and easier to harden. Manganese: improves steel processing by limiting oxidation. In high concentrations, it produces “stainless steel,” which highly resists corrosion. Here are some properties affected by these elements:Ĭhromium: makes steel stronger, harder, and easier to harden increases corrosion resistance. Common alloying elements include boron, chromium, manganese, molybdenum, nickel, and vanadium. High-carbon steel also starts out weak but can be converted to a strong, brittle steel through heat treating.Īlloying elements can be added to iron and carbon to produce steel with desirable combinations of mechanical properties for specific applications. Low-carbon steel, which has very little carbon, is weak and doesn’t respond well to heat treating. Steel made of just iron and carbon is called “carbon steel.” It is not considered an alloy steel. Scientists have given names to different geometric arrangements, such as “austenite,” “ferrite,” and “martensite.” The same steel alloy has different properties depending on how the atoms are arranged. Heat treating can also change the arrangement of the atoms. For example, larger grains slip past each other more easily, and this makes the steel softer than it would be with more small grains to resist movement better. Different grain sizes and arrangements react differently to stress. Heat treating can alter both the grain sizes and the geometric arrangement of the atoms in the steel. At a microscopic level, steel is made of small grains, which are groups of metal atoms arranged in crystals. Heat treating means raising the temperature of steel and cooling it in precise, controlled steps to change its internal structure. Strength: a material’s ability to be stressed without becoming permanently deformed.ĭuctility: a material's ability to become permanently deformed under stress before it breaks.Ī material’s combination of strength and ductility that allows it to absorb energy without breaking. Hardness: a material’s resistance to wear and scratching. Some common steel properties include the following: Instead of deforming elastically and then bouncing back when the stress is removed, hard steel will tend to break under high stress. For example, extremely hard steel will be strong, but also brittle. By mixing in alloying elements and subjecting the mixture to high heat to change its hardness, we can modify mechanical properties like hardness, strength, toughness, and ductility.Įven in the best circumstances, however, some of these properties involve tradeoffs. Without heat treating and without alloying elements, steel is too soft for use in the best hand tools. Steel is, by weight, mostly iron (often 90% or more) with small amounts of carbon (usually 0.1% to 2%) and sometimes alloying elements mixed in. Which one is better? When properly manufactured and heat treated, they are chemically almost identical and perform similarly. WHICH IS BETTER FOR HAND TOOLS? Chromium-Molybdenum or Chromium-Vanadium Steel?Ĭhromium-molybdenum (also called chrome molybdenum, chrome moly, or Cr-Mo) and chromium-vanadium (also called chrome vanadium or Cr-V) are names for two families of steel alloys used in hand tool manufacturing.
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