With more and more companies and individuals manufacturing steel targets, the water has become increasingly muddy where accurate information is concerned. With technical data provided by the American Iron and Steel Institute in Washington D.C., this report is designed to cut through the recent hype and establish a basis of fact for accurate evaluation and comparison.
What Is Steel?
Steel is an metal composed of iron plus varying amounts of carbon and/or other alloy elements such as chromium, nickel, tungsten, manganese, and so on. Different types of steel - that is, steel with different properties and characteristics - are produced by adjusting the chemical composition and adapting any of the different stages of the steel making process, such as rolling, finishing and heat treatment.
As each of these factors can be modified, there is potentially no limit to the number of different steel recipes that can be created. Currently there are over 3,000 catalogued grades or chemical compositions of steel available.
Carbon steel (the most common) depends on carbon and manganese in conjunction with proper processing to improve mechanical properties. Steel can utilize a wide variety of alloying elements and heat treatments to develop the most desirable combination of properties.
Steel Hardness
Truth - There are only 2 factors that affect the hardness of steel
The first is the amount of carbon in its chemical composition, and the second is the manner in which the heating and cooling of the steel is manipulated. These factors are determined at the most fundamental level, and affect the finished steel as a whole. There is no surface treatment or chemical application that can affect the steel’'s hardness.
Steel Manufacturing Terms
- High-Carbon Steel - Steel with more than 0.3% carbon. The more carbon that is dissolved in the iron, the tougher and less formable the steel becomes. High-carbon steel’'s hardness makes it suitable for severe, high-wear applications. “AR” or “Abrasion Resistant” steel is such a high-carbon steel.
- Low-Carbon Steel - Steel with less than 0.005% carbon is more ductile (malleable). It is capable of being drawn out or rolled thin for use in automotive body applications. Carbon is removed from the steel bath through vacuum degassing.
- Quench and Temper Cooling - Steel is rapidly cooled from above its critical temperature range (austenitizing) to a temperature far below this range. Water or oil is used to accelerate the cooling. In the quenched condition, the product is not suitable for most commercial applications because of its lower ductility and extreme hardness.
- The steel must, therefore, be tempered in order to improve its ductility and toughness and to relieve internal stresses. Left untempered, the extreme hardness and internal stresses would cause the steel to crack and even shatter under heavy strain or impact. Tempering is a reheating treatment performed at temperatures usually in the range between 400°F and 1300°F.
- Hardenability - One of the principal functions of alloying elements in steel is to increase hardenability, which is the property that determines the depth to which the steel will harden. Hardenability should not be confused with hardness. The maximum attainable hardness of any steel depends on carbon content. Alloying elements do not make the steel inherently any harder, but rather increase the depth of hardening to improve mechanical properties throughout the full cross section of the part.
- Brinell Hardness Number (BHN) - The Brinell hardness test depends upon the resistance offered to the penetration of a carbide steel ball (1.6 mm diameter) when subjected to a weight of 12.6 kg. The resulting hardness value is computed as the ratio of the applied load to the area of the indentation produced. This test is accepted as a worldwide standard for measuring the hardness of steel.
Steel Properties And Uses
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Who Uses The Best Steel?
When it comes to steel targets, important and ironic truths exist on both sides of this common question. It is important to understand these truths in order to make an educated decision when purchasing steel targets.
Truth - There is a significant difference in the quality of steel being used
Undoubtedly, there are steel targets out there that are poorly designed and are made of inferior steel. Homemade targets put together in local welding shops are usually the culprits, but some manufacturers have used inferior steel in the past as well. Because these targets are vulnerable to cratering, pocking, and general deformation, they are very dangerous and should be avoided. Any steel with a “Brinell” hardness rating much under 400 falls into this category, including standard “T-1" steel with an hardness rating near the 300 range.
Truth - There is NOT a significant difference in the quality of steel being used
This is not as big a contradiction as it may seem. After many years of experimenting to find the best solution, most major manufacturers of dependable, high quality steel targets now use what is known as “AR” or “Abrasion Resistant” steel with a Brinell hardness rating of at least 400. A few manufacturers use only AR500 steel, which is the same “AR” steel with a higher Brinell hardness rating of 500. There are only a few plants that make this kind of heavy-duty steel, and all the target manufacturers must get their supply from one of these plants. Steel of this quality and reputation is always certified by the plant that created it, regardless of which target manufacturer the steel is shipped to. Other certifications are merely cosmetic.
When all the rhetoric is boiled away, there are manufacturers who use steel that is not appropriate for targets, and there are manufacturers who use steel that is. Among the major manufacturers producing dependable, high quality steel targets, the quality of the steel itself is practically the same.
Proper Design Is Critical
Even the best steel can’'t compensate for poorly designed targets. There are several unavoidable truths that must be followed to create targets that are as safe and durable as possible.
Truth - Smooth and totally flat shooting surfaces are essential
There are 2 things manufacturers can do to ruin the smoothness and flatness of a steel target. First, they can use inferior steel that will crater, pock, and deform. Second, they can put brackets, clamps, or bolts in the way. Remember, anything that can be shot, will be shot. Why is this an issue? Because you can do a reasonable job of predicting and protecting against a bullet’'s splatter pattern when it hits a flat, uniform surface. If the steel is damaged or if anything else is in the way, all bets are off. Bullet fragmentation and ricochet are inherent and acknowledged issues when shooting on steel targets. Proper target design helps you address those issues with the highest degree of safety possible.
Truth - Dissipating a bullet’'s energy is safer and will help your targets last longer
When a bullet strikes a steel target that is completely stationary at a 90-degree angle, all the bullet’'s energy goes directly to weakening that point on the steel. If the target is completely stationary but is positioned at slightly less than a 90-degree angle, a portion of the bullet’'s energy at impact is deflected rather than absorbed. If the target is positioned at slightly less than a 90-degree angle AND the target is able to move on impact, a much larger portion of the bullet’'s energy is deflected rather than absorbed. Bottom line? Steel targets should be positioned at an angle, and they should be free to move when they are hit.
No Steel Target Is Indestructible
Without exception, every steel target out there today can be damaged. Steel hardness and proper design can both be defeated by misuse and/or abuse of the target.
Truth - The basic destructive force generated by bullets striking steel targets is heat
Excessive concentrated heat alters the steel’'s hardness properties and results in damage to the target’'s face. The amount of heat generated is proportional to the speed of the bullet, which is why rifles cause more damage to steel targets than handguns.
Truth - Rifle distance on steel targets means 75 yards minimum
No matter what anyone tells you, shooting on bare steel with a rifle at less than 25 yards can damage your target. Even at 25 yards, the target absolutely must be mounted at a significant angle, and the steel must be extremely hard (AR500).
Truth - Shotgun slug distance on steel targets also means 75 yards minimum
Shotgun slugs have the greatest potential for bodily harm to the shooter due to the sheer volume of lead that can be returned from damaged or poorly designed steel targets. Stay back!
Truth - Frangible ammunition requires the same quality steel as regular ammunition
Many types of frangible ammunition, particularly for rifles, are lighter than regular lead ammunition. Remember that lighter bullets can mean greater speed, which means more heat, which can mean damage to your steel target.
Article submitted by Action Target