Carbon steel is a misleading term -- all steel has carbon in it. Likewise, it’s hard not only to keep track of what’s considered carbon steel, but also which grades possess the qualities your project needs. That’s why we’ve compiled a carbon steel grades chart or two for you.
Use the information below to get the best use out of carbon steel. Despite its shortcomings, it’s got a lot to offer your component!
Carbon steel is an alloy of iron and carbon (shocking, we know). This steel type may also include traces of other elements, like manganese, up to a 1.65% maximum; silicon, with a 0.6% maximum; and copper, up to 0.6%.
Most folks divide this steel type into three levels of carbon content:
Here are the most common carbon steel grades, in chart form. If you don’t want to put a lot of effort into your material picking, stick with these common types of tubular steel -- your steel tube manufacturer will know all about them.
| GRADE | TRAITS | USES |
| 12L14 | Free machining. Lead added to enhance machinability. Addition of lead does, however, reduce tensile strength, although it’s still generally stronger than 1018. Magnetic in all conditions. | Brake hose ends, pulleys, gear box components, wheel nuts and inserts, disc brake pistons, padlock shackles, control linkages, garbage bin axles, concrete anchors, hydraulic fittings, vice jaws |
| 8620 | Hard outer surface, combined with a ductile interior for higher strength. | Gears, crankshafts, gear rings |
| A36 | Chemically similar to 1018 but has inferior properties and rougher finish. Most commonly available of the hot-rolled steels. Yield strength also significantly less than 1018 | Automotive components, cams, fixtures, tanks, forgings and structural applications such as buildings or bridges |
| A513 (alloy 1020-1026) | Its higher carbon content means higher strength, but lower weldability and machinability. | Drawn over mandrel tubing |
| 1008 | Highest thermal conductivity among wrought plain carbon steels. Can have the lowest tensile strength and moderately high ductility. Excellent weldability. | Machinery parts, tie rods, relatively low-strength structural applications, mounting plates and brackets |
| C1010 | Relatively low strength, but can be quenched and tempered to increase strength at a high cost. Fairly good machinability; good formability and ductility. | Machinery parts, tie rods, relatively low-strength structural applications, mounting plates and brackets |
| C1018 | Most commonly available cold-rolled steel. Has strength, some ductility, and comparative ease of machining. | Machinery parts, tie rods, relatively low strength structural applications, mounting plates and brackets |
| C1045 | For applications in which more strength or higher hardness than that of 1008 or 1010 is required. | Bolts, gears, crank shafts, cylinder shafts, die forges |
| C1141 | For applications similar to those of 1045, but machinability is very important. | Pins, studs, bolts, shafts, tie rods |
| C1144 | Higher strength than 1018 or A36, but in addition has improved ductility. Very low distortion or warping after machining due to a combination of its chemistry, method of manufacture, and heat treatment. Relatively easy to machine. | Pins, studs, bolts, shafts, tie rods, applications similar to those of 1045 when machinability is very important |
You’re probably wondering what all these intimidating numbers mean.
In general, the first number of each grade depicts a general category of steels. They are:
The second number indicates the presence of elements that affect the steel’s traits.
For example, the zero in a 10XX grade indicates there are no major secondary elements, such as sulfur, inside. Why would this matter? Sulfur, lead, and other elements in steel can increase machinability. Yet they can also cause pockets or other faults that can hamper some applications.
The last two characters represent the steel’s carbon content.
A piece of 1018 steel contains 0.18% carbon. Note that standards will actually show an allowable carbon range of 0.15-0.20% for this grade. That’s because it’s impossible for steel makers to control carbon and alloy contents with flawless precision.
The most important and desired changes in alloy steel are:
| 301, 301L, 301LN | High strength for roll formed structural components |
| 302HQ | Low work hardening rate grade for cold heading fasteners |
| 303, 303Se | Free-machining bar grades |
| 304, 304L, 304H | Standard 18/8 grades |
| 310, 310S, 310H | High temperature resistant grades |
| 316, 316L, 316H | Improved resistance to pitting corrosion in chloride environments |
| 321, 321H, 347 | Stabilised grades for heavy section welding and high temperature applications |
| 253MA | High temperature resistant grade |
| 904L | High resistance to general corrosion, pitting and stress corrosion cracking |
| AtlasCR12 | Utility steel resistant to wet abrasion and mild corrosion |
| AtlasCR12Ti | Utility steel resistant to wet abrasion and mild corrosion - weld stabilised |
| 409 | Automotive exhaust grade - weld stabilised |
| 430, 430F | Resistant to mildly corrosive environments |
| 3F18S | Resistant to mildly corrosive environments - weld stabilised |
| F18MS / 444 | A ferritic alternative to grade 316 / 316 L - Weld stabilised |
| F20S | A ferritic alternative to grade 304 / 304L - Weld stabilised |
| 2101 | Lean duplex for tanks and structural applications |
| 2304 | Duplex alternative to grade 316 |
| 2205 | Standard duplex stainless steel - high resistance to pitting and stress corrosion |
| 2507 | Super duplex with very high resistance to pitting and stress corrosion |
| 2507Cu | Super duplex with very high resistance to pitting and stress corrosion |
| 410 | Standard martensitic grade for low-duty hardened applications |
| 416 | Free-machining bar grade |
| 420 | Higher hardness martensitic grade for cutlery, cutting tools and dies |
| 431 | High hardness and toughness grade, primarily for shafting |
| 440A, 440B, 440C | Very high hardness grades used in cutting tools |
| 630 | (17-4PH) High strength shafting grade |
Stainless steels have traditionally been divided into types depending on their microstructure at room temperature, which gives a rough indication of their composition and properties.
stainless steels can be divided into four main types: ferritic, martensitic and precipitation hardening, duplex, and austenitic – the best steel for you depends on the application.
The standard ferritic grades are alloyed with chromium (11.2–19%), but with no, or a very small, addition of nickel. As nickel is one of the most expensive alloying elements, and experiences high price volatility, the low nickel content of the ferritic grades makes them more price stable compared to grades with high nickel content. Molybdenum is added to some grades to improve corrosion resistance, while alloying with niobium and/or titanium improves weldability. The ferritic grades are magnetic due to their ferritic microstructure. There are also ferritic grades with increased resistance to high temperatures (800–1,150 °C). These grades are typically alloyed with more carbon than standard ferritic grades to increase creep strength, and with silicon and aluminum to improve resistance to oxidation.
The martensitic grades are the smallest group of stainless steels. For improved strength and hardenability they have a higher carbon content compared to other grades, and nitrogen is sometimes added to further improve strength.
These grades contain no, or small, amounts of nickel, and molybdenum is seldom added. Adding some nickel and reducing the carbon content improves the poor weldability of martensitic grades. Sometimes sulfur is added to improve the machinability.
The precipitation hardening grades are hardened by a special mechanism involving the formation of precipitates within the microstructure. Both martensitic and precipitation hardening stainless steels are magnetic.
Duplex grades have a ferritic-austenitic microstructure that combines many of the beneficial properties of ferritic and austenitic stainless steels. The duplex microstructure also contributes to high strength and high resistance to stress corrosion cracking.
Duplex stainless steels are characterized by high chromium content (20.1–25.4%) and low nickel content (1.4–7%) compared to austenitic grades. The low nickel content makes duplex grades more price stable.
Molybdenum (0.3–4%) and nitrogen are added to improve corrosion resistance, while nitrogen also increases strength. The duplex grades LDX 2101 and 2304 are sometimes referred to as lean duplex grades, while the duplex grades 2507 and 4501 are also called 25Cr superduplex grades. Due to their ferrite content the duplex grades are magnetic.
he austenitic grades are the largest type of stainless steels, and can be divided into five sub-groups:
The austenitic grades have good to excellent corrosion resistance, as well as good formability and weldability. Their high impact strength at low temperatures is often exploited in cryogenic applications. The austenitic grades are non-magnetic in the solution-annealed condition. Cold working increases their strength and certain grades are therefore supplied in the temper rolled condition and may then be magnetic due to the presence of some martensite.
The 6000 grades of aluminium are also known as the magnesium and silicon grades. Magnesium and silicon are the two main alloying constituents in all 6000 grades and specifications of aluminium.
Grade 6082 is the most common grade of commercial aluminium sections & plates, whilst T6 is the most common temper.
Grade 6063 is a medium strength alloy, it is the most common grade of aluminium for extruding. As far as commercial aluminium sections are concerned, T6 is the most common temper available.
Grade 6061 aluminium is a medium strength aluminium alloy that is predominantly produced for the American market. Grade 6082 is the nearest equivalent grade to this that is readily available in the UK, with very slight differences between the two.
The 1000 series grades of aluminium are the purest out of all the commercial aluminium grades. Each and every grade in the 1000 series contains a minimum of 99% pure aluminium within it. This high aluminium content gives the 1000 series grades exceptional resistance strength.
Grade 1050 is the most common grade of aluminium sheet available in the UK. Grade 1050 aluminium has the lowest strength of all the commercial grades of aluminium. It is most commonly available in H14 temper, which in technical terms is classed as half hard.
1050H14 is an extremely ductile grade of aluminium, and therefore it is most commonly used by fabricators and sheet metal workers who will bend and form the sheet into a requested shape.
Magnesium is the main element used in the composition of the 5000 series grades of aluminium. The 5000 series grades of aluminium are non heat-treatable alloys. The 5000 series grades also have excellent resistance to corrosion caused by saltwater, for this reason they are often referred to as the Marine Grades of aluminium.
Grade 5083 has the highest strength of all of the non heat treatable alloys, although it is not as strong or as hard as the more common grade 6082. Grade 5083 is primarily available in plate form, and is most commonly available in O condition.
Grade 5754 is a medium strength alloy. For comparison it is not a strong as grades 6082 or 5083, but 5754 is stronger than grade 5251. Grade 5754 is most commonly used to produce aluminium 5 bar treadplate (often referred to as aluminium chequer plate).
Grade 5251 is a medium strength alloy, usually supplied in sheet form, and is most commonly supplied in temper H22. Previously known as NS4, grade 5251 has many similar attributes to grade 1050 aluminium sheet and is probably the 2nd most popular grade of aluminium sheet used in the UK today.
Known as the zinc grades – zinc being the largest alloying element, the 7000 series grades are the hardest and strongest commercial grades of aluminium.
Grade 7075 is the most common of the 7000 series grades. It is an extremely high strength alloy; the strongest of all commercial grades of aluminium. In fact, grade 7075 aluminium is stronger than many types of mild steel.
The 2000 series grades are known as the copper grades of aluminium, copper being the main alloying element. The addition of copper increases the alloys strength and hardness, which in turn improves its machinability.
Grade 2011 is a high performance, high strength aluminium alloy. Grade 2011 is usually supplied in round bars.
Grade 2014 is a high strength aluminium alloy, supplied in bar and plate form. It has excellent machinability and is often interchanged with grade 2011.
A common misconception is that there is an “Aerospace grade” or “Aircraft spec” of aluminium. Various grades of aluminium from (but not limited to) the 1000 series, 2000 series, 5000 series, 6000 series and 7000 series grades of aluminium are routinely used in the aerospace industry. The aerospace industry does have a greater demand for harder grades, such as 7075, 2011, 2014, 6061 & 6082 than many other industries do, however the exact grade or specification used is very much dependant on the application. Today phrases such as “Aircraft aluminium”, “Aerospace aluminium”, “Aerospace grade aluminium” and “Aircraft spec aluminium” are generic terms used by the masses to describe a hard, machinable aluminium alloy.
Dural is an obsolete trade name for a heat treatable aluminium copper alloy. Also known as Duralumin, Duraluminium, Duralum & Duralium, the original Dural contained around 4 – 5% copper, 0.5 – 1% Manganese and 0.5 – 1.5% Magnesium which makes it very close in composition to grades 2014 & 2024. Today the term “Dural” is often used as a generic term to describe any type of aluminium that has good strength and is suitable for machining.
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