Steel types and how to use them
Introduction
There are three main types of steel we work with as blacksmiths and knifemakers: mild steel, carbon steel, and stainless steel. Mild steel is generally available in two grades, A36 and 1018, with 1018 being the purest of the two. Mild steel is readily available in stores and steel suppliers, but it does not contain enough carbon to harden, making it unsuitable for knife steel. Carbon steel is the term we use for steel with a carbon content between 0.4% and 1.5% carbon, with most knife steels being between 0.7% and 1.2%. The third type is stainless steel, which contains at least 10.5% chromium. It is available in martensitic and austenitic, as well as in hardenable and non-hardenable forms. Since we want to talk about steel forging and knife forging that are commonly used, we will focus on carbon steel.
1080
1080 is a "simple" high carbon steel, one of our favorites for its ease of use and high performance. We use 1080 in our Damascus steel as the dark layers in the pattern. Because of its forgiving nature, the 1080 is a favorite of novice knife makers and bladesmiths; however, it offers a level of performance high enough to still be commonly used by master blacksmiths. The carbon content of steel is 0.8%, which is just right for many different applications. It has a fairly generous window of malleable temperatures; it does not mind going to a high yellow color during welding and there is no stress from breaking easily in the 1500°F (816°C) range.
Heat treatment
- Heat to 816°C (1500°F), just above critical temperature, and quench in hot oil. Tempers twice, in 2-hour cycles, allowing cooling to room temperature between cycles. Use 204°C (400°F) for high hardness or 218°C (425°F) for high toughness/flexibility.
Element: Content %
- Iron: 98.0 - 99.0
- Carbon: 0.75 - 0.88
- Manganese: 0.60-0.90
User
- Knives of all sizes, swords, woodworking tools, axes, Damascus stock.
15n20
15n20 is an alloy steel with high carbon content and high nickel content; it is extremely strong and versatile. We choose 15n20 in combination with 1080 for our Damascus steel. This forms the light layers in the pattern because the nickel in the steel resists the ferric chloride we use to etch knives. It has a carbon content of 0.75% and moves similar to 1080, while having a different heat treatment and final hardness. The alloy of nickel in 15n20 provides a little extra toughness and allows it to get a sharper edge than many other types of carbon steel.
Heat treatment
- Heat to 816°C (1500°F), just above critical temperature, and quench in hot oil. Tempers twice, in 2-hour cycles, allowing cooling to room temperature between cycles. Use 350°F (177°C) for high hardness or 400°F (204°C) for high toughness/flexibility.
Element: Content %
- Nickel: 1.4-2
- Carbon: 0.75-80
- Iron: .40-.45
- Phosphorus: ,10-,15
User
- Knives of all sizes, swords, woodworking tools, axes, Damascus stock.
L-6
L-6 is a high nickel steel that is ideal for tools that require extreme toughness, such as swords, large knives, axes and other tools that must withstand high stress situations. It has a more specific forging temperature range than other steels such as 1080 and 15n20. It cannot be forged as hot or as cold as the more forgiving steels.
Heat treatment
- Heat to 816°C-843°C (1500°F-1550°F) and hold for 10-30 minutes, cool in hot oil. Tempers twice at 350°F (177°C), in 2 hour cycles for high hardness and at 450°F (232°C) for high strength/durability in knives or at 500°F-600°F (260°C ) -316°C) for cold working tools.
Element: Content %
- Nickel: 1.25-2.00
- Except: 0.60-1.20
- Carbon: 0.65-0.75
- Silicon: 0.5
- Molybdenum: 0.5
- Manganese: 0.25-0.80
- Vanadium: 0,20-0,30
- Copper: 0.25
- Phosphorus: 0.03
- Sulfur: 0.03
User
- Large knives, swords, axes and other sharp tools.
4140
4140 is a type of chrome-molybdenum medium carbon steel often used in industry for anything that requires more strength than mild steel. It is preferred for industrial applications such as axes, shafts, tools, etc. For forging, it is usually for heavy duty tools that do not require fine edge retention.
Heat treatment
- Heat to 843°C (1550°F), just above critical temperature, and quench in hot oil. Tempers twice, in two-hour cycles, allowing cooling to room temperature between cycles. Use 204°C (400°F) for high hardness or 232°C (450°F) for high toughness/durability.
Element: Content %
- Except: 0.80 - 1.10
- Manganese: 0.75 - 1.0
- Carbon: 0.380 - 0.430
- Silicon: 0.15 - 0.30
- Molybdenum: 0.15 - 0.25
- Sulfur: 0.040
- Phosphorus: 0.035
User
- Axes, Power Hammer Dies, Punches, Drivers, Hammers, Top Tools, Bottom Tools.
4340
4340 is a strengthened version of 4140, with a higher nickel content than 4140; it has improved edge retention and performs better under high temperatures. 4340 is the steel from which we make our hammer eye drive, and it is an excellent choice for similar tools in forging/blade forging.
Heat treatment
- Heat to 843°C (1550°F), just above critical temperature, and quench in hot oil. Temper twice, in 2-hour cycles, and allow to cool to room temperature between cycles. Use 204°C (400°F) for high hardness or 260°C (500°F) for high toughness/durability.
Element: Content %
- Iron: 95.195 - 96.33
- Nickel: 1.65 - 2.00
- Except: 0.700 - 0.900
- Manganese: 0.600 - 0.800
- Carbon: 0.370 - 0.430
- Molybdenum: 0.200 - 0.300
- Silicon: 0.150 - 0.300
- Sulfur: 0.0400
- Phosphorus: 0.0350
User
- Axes, Power Hammer Dies, Punches, Drifts, Hammers, Top Tools, Bottom Tools.
1045
1045 is a simple medium carbon alloy and is our choice for hammer steel because it has the right mix of hardness and toughness. It's a bit soft to make a good axe, knife or sword, but for non-sharp tools that require simple and consistent forging and heat treatment, it's often a good option.
Heat treatment
- Heat to 843°C-871°C (1550°F-1600°F), just above critical temperature, and deglaze in hot oil for thin pieces, or water for pieces over 1 inch thick. Temper twice within 2 hour cycles, cooling to room temperature between cycles. Use 316°C (600°F) for high hardness or 482°C (900°F) for high toughness/durability.
Element: Content %
- Carbon: 0.420 - 0.50
- Iron: 98.51 - 98.98
- Manganese: 0.60 - 0.90
- Phosphorus: ≤ 0.040
- Sulfur: ≤ 0.050
User
- Hammers, splitting hammers.
H-13
H13 is a hot tool steel, meaning it resists deformation when subjected to high temperatures, such as punching or forming hot steel in various operations. It is the industry standard for hot punches, drifts and dies. H13 is considerably more robust than other forging steels, and care must be taken when heat treating as it is an air-hardening steel. Improper use of this steel can cause the tool you make to break or damage other tools and possibly cause injury.
Heat treatment
- Heat to 1010°C (1850°F), hold for 15-40 minutes and cool in room air. Temper twice, in 2-hour cycles, and allow to cool to room temperature between cycles. Use 1000°F (538°C) for high hardness or 1125°F (607°C) for high toughness/durability.
Element: Content %
- Except: 4.75-5.50
- Molybdenum: 1.10-1.75
- Silicon: 0.80-1.20
- Vanadium: 0,80-1,20
- Carbon: 0.32-0.45
- Nickel: 0.3
- Copper: 0.25
- Manganese: 0.20-0.50
- Phosphorus: 0.03
- Sulfur: 0.03
User
- Punching, drifting, Power Hammer dies, hot blades.
