ASTM steel grade reference.
Common ASTM steel grades — yield strength, tensile strength, and typical applications. The quick reference for picking the right steel for structural, pressure, machining, and corrosion-resistant applications.
The chart
| Designation | Type | Yield (ksi) | Tensile (ksi) | Typical use |
|---|---|---|---|---|
| A36 | Carbon structural | 36 | 58-80 | General construction — beams, plate, angle iron. Most common low-strength structural steel. |
| A572 Gr 50 | HSLA structural | 50 | 65 min | Bridges, buildings — higher strength than A36 at similar cost. |
| A992 | Wide-flange beams | 50-65 | 65 min | W-shape structural beams (replaced A36/A572 for W-shapes since 1998). |
| A500 Gr B | HSS structural tube | 46 (rect.) / 42 (round) | 58 min | Square / rectangular structural tubing. Common in modern construction. |
| A572 Gr 65 | HSLA high-strength | 65 | 80 min | High-strength bridges, heavy industrial. |
| A1011 / A1018 | Carbon sheet/plate | 30-50 | 49-65 | Commercial-quality steel sheet — cold or hot rolled. |
| A283 Gr C | Low-carbon plate | 30 | 55-75 | Storage tanks, general structural plate. |
| A53 Gr B | Pipe (structural + flow) | 35 | 60 min | Standard pipe — Type E (electric welded), Type F (furnace butt-welded). |
| A106 Gr B | Seamless pipe (high temp) | 35 | 60 min | Pressure / high-temperature steam service. |
| A516 Gr 70 | Pressure vessel plate | 38 | 70 min | Boilers, pressure vessels — moderate / low temperature. |
| A537 Cl 1 | Pressure vessel (Q&T) | 50 | 70-90 | Higher-strength pressure vessels, quenched and tempered. |
| 1018 | Low carbon (cold rolled) | 54 | 64 | Machine shafts, general purpose, weldable. Easy to machine. |
| 1045 | Medium carbon | 45-60 | 82-91 | Higher-strength shafts, axles. Flame / induction hardenable. |
| 1144 | Free-machining stressproof | 100 | 115 | Resulfurized, prehardened. Better machinability than 1045. |
| 4140 | Alloy (Cr-Mo) | 60-200 | 90-220 | Heat-treatable. Shafts, gears, high-strength fasteners. Hardenable to 50+ HRC. |
| 4340 | Alloy (Ni-Cr-Mo) | 60-220 | 100-260 | Aircraft, high-strength shafts. Superior toughness vs 4140. |
| 8620 | Low-alloy carburizing | 40-90 | 55-180 | Gears, camshafts. Surface-hardened by carburizing. |
| 304 / 304L | Austenitic stainless | 30 | 75 | Food, chemical, kitchen. Non-magnetic, weldable. The default stainless. |
| 316 / 316L | Austenitic stainless (Mo) | 30 | 75 | Marine, chemical. Better corrosion (chloride) resistance than 304. |
| 17-4 PH | Precipitation-hardened | 170 | 190 | Aerospace shafts, valves. Heat-treatable to high strength. |
| 410 | Martensitic stainless | 35-85 | 70-110 | Hardenable. Valve stems, fasteners, cutlery. |
| 416 | Martensitic (free-machining) | 40-85 | 75-110 | Free-machining version of 410. Valve parts. |
| A588 (Cor-Ten) | Weathering steel | 50 | 70 | Forms a protective rust patina — used in bridges, architecture. |
| A572 Gr 60 | HSLA | 60 | 75 min | Bridges (between Gr 50 and Gr 65 use cases). |
| A656 Gr 80 | Microalloyed HSLA | 80 | 90 min | Heavy-equipment frames, where high strength matters. |
About these designations. ASTM (American Society for Testing and Materials) designations begin with 'A' for ferrous metals; the number is the standard number, not a property. Yield and tensile values shown are minimum spec — actual material typically tests 10-20% higher. For heat-treatable alloys (4140, 4340, etc.), the strength range reflects different heat-treat conditions.
Common applications
| Application | Recommended grade | Reason |
|---|---|---|
| Residential beams, columns | A36 or A992 | Cheap, weldable, code-accepted |
| Commercial steel framing | A992 (W-shapes), A500 (HSS) | Modern standards |
| Bridges | A572 Gr 50, A588 | Higher strength + weatherproof |
| Pressure vessels (moderate T) | A516 Gr 70 | Standard ASME pressure vessel grade |
| Hydraulic cylinder shaft | 1045 or 4140 (hardened) | Wear resistance, strength |
| Bolts (Grade 5 equivalent) | Medium carbon, SAE J429 | SAE 4140 for high-grade variants |
| Gear teeth | 8620 (carburized) or 4140 | Surface hardness + tough core |
| Marine hardware | 316 stainless | Chloride corrosion resistance |
| Food / kitchen contact | 304 stainless | Easy to clean, non-reactive |
| Architectural exposed | A588 (Cor-Ten) or 316 stainless | Weather resistance |
| Machine shop general stock | 1018 | Easy to machine, weld; cheap |
Common pitfalls
- 'Steel' alone is ambiguous. A36 and 4340 are both 'steel' but differ by 5× in strength. Always specify a grade.
- Stainless isn't immune to corrosion. 304 corrodes in saltwater; 316 is better but still pits eventually. For severe chloride or acid environments, use duplex, super duplex, or specialized alloys.
- Yield ≠ working strength. Allowable stress for structural design is typically 60-66% of yield (ASD method) — never the full yield value. Code-mandated safety factors apply.
- Hardness ≠ strength directly. A 50 HRC tool steel can be very strong AND very brittle. Working strength requires both strength AND toughness. Quenched-and-tempered 4140 at 30 HRC may be more useful than untempered 4140 at 60 HRC for many applications.
- Welding considerations vary widely. A36 welds easily with no preheat. 4140 needs preheat and post-weld stress relief to avoid cracking. High-strength steels (above ~80 ksi yield) often have welding restrictions.
- Tensile vs yield: don't confuse. Yield is where the steel permanently deforms. Tensile is where it breaks. The ratio (yield/tensile) tells you ductility — higher ratios mean more brittle. 4340 quenched and tempered has yield close to tensile; A36 has wide gap (high ductility).
Common questions
What's the difference between A36 and A572?
A36 is structural carbon steel with a yield strength of 36 ksi (250 MPa) — the most common, cheapest, easiest to weld. A572 Grade 50 is a high-strength low-alloy steel with 50 ksi (345 MPa) yield, used when you need more strength-to-weight in beams and columns. A572 is harder to weld and slightly more expensive but lets you use smaller sections for the same load.
Is A992 the same as A572 Grade 50?
They're close but not identical. A992 is the modern standard for W-shape (wide-flange) structural beams and has a tighter yield-strength range (50-65 ksi) than A572 Grade 50 (50 ksi minimum). A992 also limits carbon content for better weldability. If a drawing calls for A572 Grade 50 beams, A992 will satisfy it; the reverse isn't always true.
Can I substitute A53 for A500 HSS?
Not interchangeably. A53 is a pipe spec — round only, lower yield (35 ksi for Grade B). A500 is hollow structural section for round, square, or rectangular tubing with higher yield (46 ksi for Gr B rectangular, 42 ksi for round). Round A53 looks similar to round A500 but has different mechanical properties; always verify the drawing's exact callout.
Why are some grades measured in ksi and others in MPa?
It's a regional convention, not a material difference. ASTM uses ksi (kips per square inch) because it's the US/customary standard; European EN standards use MPa (megapascals). 1 ksi ≈ 6.895 MPa, so 36 ksi = 248 MPa, 50 ksi = 345 MPa. Material data sheets often list both for international use.
Which grade should I use for a residential project?
For most residential and light-commercial construction, A36 (plates and angles) and A992 (W-shape beams) cover the vast majority of uses. A36 is forgiving, weldable, and inexpensive. Use higher grades like A572 or A913 only when the structural engineer specifies them for span or load reasons — they cost more and offer no benefit unless the design uses the extra strength.
Sources
- Structural: AISC Steel Construction Manual; ASTM A6 (general requirements for rolled structural steel).
- Pipe: ASTM A53, A106, A312 (stainless pipe).
- Pressure vessel: ASTM A516, A537; design per ASME BPVC Section VIII.
- Alloy steels: AISI/SAE designations; ASTM grade tables in ASM Metals Handbook.
Disclaimer. Steel grade selection depends on application, service environment, fabrication method, and applicable code. For structural, pressure-rated, or safety-critical work, consult the relevant code (AISC, ASME, AWS) and a qualified materials engineer.