--- title: "Steel CNC Machining & Fabrication | 1018, 4140, A36, 12L14 | OpenSpindle" description: "Get quotes for custom carbon and alloy steel parts from independent machine shops. 1018, 1045, 4140, 4130, A36, 12L14, and tool steels, machined, turned, cut, and coated. Upload a drawing." canonical: https://openspindle.com/materials/carbon-steel --- # Custom steel parts from independent machine shops Carbon and alloy steel are the strongest, stiffest, and lowest-cost-per-pound metals shops run. Upload a drawing and hear back from shops that machine 1018, 4140, A36, and tool steels every day. ## Carbon steel shops on OpenSpindle Real shops that machine and fabricate carbon and alloy steel. See their equipment and talk to the person making your part. [Browse all carbon steel shops](https://openspindle.com/manufacturers?material=1018%20cold%20rolled%2C4140%2CA36%2C12L14) ## Steel grades shops run most The grade sets strength, machinability, and whether the part can be hardened. These are the ones you will see quoted; if yours is not here, ask when you request a quote. ### 1018 cold rolled The default low-carbon steel. Good machinability and weldability, a clean cold-drawn surface, and low cost. Not hardenable by heat treat, but case-hardens well for wear surfaces. **Best for:** Shafts, pins, spacers, brackets, and general parts ### 12L14 A leaded free-machining steel that cuts faster and cleaner than any other carbon grade. Low strength and poor weldability, so it is used where speed and finish matter more than load. **Best for:** Screw-machine parts, fittings, bushings, high-volume turned parts ### 1045 Medium-carbon steel with higher strength than 1018 and the carbon to through-harden or flame/induction harden. Machines and welds reasonably, a common step up when 1018 is not strong enough. **Best for:** Shafts, axles, gears, studs, and stressed parts ### A36 hot rolled The structural plate and bar standard. Low cost, welds easily, and readily available, but comes with mill scale and looser tolerances than cold-rolled stock. **Best for:** Weldments, frames, base plates, brackets, structural parts ### 4140 pre-hardened A chromium-molybdenum alloy supplied pre-hardened to about 28-32 HRC with high strength and toughness. Machinable in the pre-hard condition, no heat treat needed for most parts, though preheat helps when welding. **Best for:** Shafts, gears, high-strength fixtures, tooling, mold bases ### 4130 chromoly A weldable chromium-molybdenum alloy with a strong strength-to-weight ratio. Welds far better than 4140 and is common in tube and plate for frames and structures that see high load. **Best for:** Roll cages, aircraft and motorsport structure, welded assemblies ### Tool steels (D2 / A2 / O1 / S7) Hardenable high-carbon, high-alloy grades machined soft then heat treated to 55-62 HRC. D2 and A2 hold an edge for cutting and forming, O1 is easy to harden for one-offs, and S7 resists shock. **Best for:** Dies, punches, cutting and forming tools, wear parts ## Material Properties Representative values for 1018 cold rolled, the most common machining grade. Exact numbers vary by grade and heat treat. | Property | Value | | --- | --- | | Density | 7.87 g/cm³ (0.284 lb/in³) | | Tensile strength (1018 CR) | ~64 ksi (440 MPa) | | Yield strength (1018 CR) | ~54 ksi (370 MPa) | | Hardness (1018 CR) | ~126 HB | | Hardness (4140 pre-hard) | ~28-32 HRC | | Machinability | Good; 12L14 excellent (free-machining benchmark ~160%) | | Corrosion resistance | Poor. Rusts; must be coated or oiled | | Weldability | 1018/A36/4130 good; 4140 and up need preheat | Steel is roughly three times the weight of aluminum and cuts slower, but delivers the highest strength and stiffness per dollar, which is why it dominates structural, high-load, and tooling parts. ## Stock Forms - **Plate & block** -- Milled and machined parts, weldment plate, and mold bases from solid. - **Round bar** -- Turned shafts, pins, axles, and cylindrical parts. - **Sheet** -- Laser, plasma, and press-brake sheet metal and weldments. ## Processes That Run This Material - [CNC Machining](https://openspindle.com/capabilities/cnc-machining.md) -- Milled brackets, plates, and prismatic parts from plate and block. - [CNC Turning](https://openspindle.com/capabilities/cnc-turning.md) -- Turned shafts, pins, and fittings from round bar, ideal for 12L14 and 1018. - [Sheet Metal & Press Brake](https://openspindle.com/capabilities/sheet-metal-fabrication.md) -- Cut, bent, and welded brackets, frames, and enclosures from steel sheet and plate. - [Welding](https://openspindle.com/manufacturers?capability=Welding) -- MIG and TIG weldments in A36, 1018, and 4130 chromoly. - [Laser Cutting](https://openspindle.com/manufacturers?capability=Laser%20cutting) -- Fast, precise flat cuts in steel sheet and thin plate. - [Waterjet Cutting](https://openspindle.com/manufacturers?capability=Waterjet%20cutting) -- Cold cutting for thick steel plate with no heat-affected edge. - [Grinding](https://openspindle.com/manufacturers?capability=Grinding) -- Precision ground surfaces and tight tolerances on hardened tool steel. - [EDM](https://openspindle.com/manufacturers?capability=EDM) -- Wire and sinker EDM for hardened tool steel and fine detail. ## Finishes Steel rusts, so nearly every part gets a finish, plating, or oil. The right one depends on the environment and whether the surface is cosmetic. - **Black oxide** -- A thin conversion coating that turns the surface black and adds mild corrosion resistance. Dimensionally negligible, so it is common on toleranced parts, followed by oil for real protection. - **Zinc plating** -- An electroplated sacrificial layer, clear or yellow, that protects steel in indoor and mild outdoor use. The go-to low-cost corrosion finish for hardware and brackets. - **Nickel plating** -- A harder, brighter plated layer with better corrosion and wear resistance than zinc. Used where appearance and durability both matter. - **Powder coat** -- Durable colored coating over a broad range of textures. Thicker than plating, so mask threads and mating faces and account for the added thickness. - **Bluing** -- A controlled black oxide finish traditional on firearms and tooling. Cosmetic and mildly protective, and needs oil to prevent rust. - **Oil / rust-preventive** -- A light oil or wax film that ships with bare or black-oxide parts. The minimum protection; bare steel begins to rust within hours of machining without it. - **As-machined** -- No finish. Only for internal or short-lived parts, and it must be oiled immediately or it will rust. Unlike aluminum or stainless, carbon steel has no natural corrosion protection. Specify a coating or oil with your drawing, or the part will rust before it reaches you. ## Applications - Automotive - Agriculture & heavy equipment - Structural & construction - Tooling & dies - Firearms - Industrial machinery - Shafts & gears - Industrial / OEM Steel shows up wherever strength, stiffness, hardness, or cost matter more than weight or corrosion resistance. ## How It Compares How carbon steel stacks up against the other metals shops quote most. ### [Aluminum](https://openspindle.com/materials/aluminum.md) - Steel is stronger and stiffer for the same volume, and costs less per pound - Aluminum is about one-third the weight and machines several times faster - Aluminum does not rust; steel must be coated or oiled to survive **Verdict:** Choose carbon steel for maximum strength, stiffness, and hardness at low cost. Choose aluminum for light, fast, corrosion-free parts. ### [Stainless steel](https://openspindle.com/materials/stainless-steel.md) - Stainless resists corrosion with no coating; carbon steel rusts without a finish - Carbon steel is cheaper, machines more easily, and can hit higher hardness in tool grades - Stainless holds up better in food, medical, marine, and chemical environments **Verdict:** Choose carbon steel for strength and cost when the part is coated or lives indoors. Choose stainless when corrosion resistance or hygiene is required. ### [Titanium](https://openspindle.com/materials/titanium.md) - Titanium has a far better strength-to-weight ratio and does not corrode - Carbon steel is several times cheaper, easier to machine, and stiffer for the same volume - Titanium is biocompatible and handles heat and chemicals carbon steel cannot **Verdict:** Choose carbon steel for cost, stiffness, and hardness. Choose titanium when strength-to-weight, corrosion, or biocompatibility justify the premium. ## Frequently Asked Questions ### What is the difference between carbon steel and alloy steel? Carbon steels like 1018, 1045, and A36 get their properties mainly from carbon content and are the low-cost workhorses. Alloy steels like 4140 and 4130 add elements such as chromium and molybdenum for higher strength, toughness, and hardenability. Use carbon grades for general parts and alloy grades when you need more strength or the ability to heat treat. ### What is the difference between 1018 and 12L14? 1018 is a general-purpose low-carbon steel with good strength, weldability, and a clean cold-rolled surface. 12L14 adds lead for free machining, so it cuts faster and to a finer finish, but it is weaker and does not weld well. Choose 1018 for structural or welded parts and 12L14 for high-volume turned or screw-machine parts. ### Does carbon steel rust? Yes. Carbon and alloy steels have no natural corrosion protection and begin to rust within hours of machining. Almost every steel part gets a finish such as black oxide, zinc or nickel plating, powder coat, or at minimum a rust-preventive oil. Specify the finish with your drawing, and if you need corrosion resistance with no coating, consider stainless steel. ### What steel should I use for a hardened or wear part? 4140 pre-hardened comes ready at about 28-32 HRC and needs no heat treat for most high-strength parts. For higher hardness, tool steels like D2, A2, O1, and S7 are machined soft then hardened to 55-62 HRC for dies, punches, and cutting tools. Medium-carbon 1045 can also be flame or induction hardened on wear surfaces. ### Can carbon steel be welded? Low-carbon grades weld well: 1018, A36, and 4130 chromoly are common in weldments. Higher-carbon and alloy grades like 1045 and 4140 need preheat and often post-weld stress relief to avoid cracking. Note the grade and any weld requirements on your drawing so the shop can plan the process. ### Is carbon steel cheaper than stainless or aluminum? Per pound, carbon steel is the cheapest of the three, and grades like A36 and 1018 are stocked everywhere. It also delivers the most strength and stiffness per dollar. The tradeoff is weight (about three times aluminum) and that it must be coated or oiled to prevent rust, which adds a finishing step. ### What file formats should I send for a steel part? STEP, IGES, X_T, DWG, DXF, or a dimensioned PDF. Include the grade (for example 1018, 4140, or A36), critical dimensions and tolerances, quantity, any heat treat or hardness target, and the finish such as black oxide or zinc plating. ## Related Materials - [Aluminum](https://openspindle.com/materials/aluminum.md) - [Stainless Steel](https://openspindle.com/materials/stainless-steel.md) - [Titanium](https://openspindle.com/materials/titanium.md) - [Brass](https://openspindle.com/materials/brass.md) - [Copper](https://openspindle.com/materials/copper.md) - [Delrin](https://openspindle.com/materials/delrin.md) ## Get carbon steel part quotes Upload a drawing once and compare quotes from independent shops that machine, cut, and finish carbon and alloy steel.