Material Properties Reference
Common Steels
| Material | Grade | Hardness | Tensile (ksi) | Machinability % | Notes |
|---|
| Low Carbon | 1018 | 126 BHN | 64 | 70 | General purpose, easy to weld |
| Medium Carbon | 1045 | 170–210 BHN | 82 | 57 | Heat treatable, shafts & gears |
| Alloy | 4130 | 197 BHN | 97 | 70 | Chrome-moly, aerospace tubing |
| Alloy | 4140 | 197–235 BHN | 95 | 66 | Versatile alloy, heat treatable |
| Alloy | 4340 | 217–255 BHN | 108 | 50 | High strength, aircraft landing gear |
| Case Hardening | 8620 | 149–197 BHN | 77 | 66 | Carburizing grade, gears & pinions |
| Tool Steel | A2 | 57–62 HRC | — | 36 | Air hardening, dies & punches |
| Tool Steel | D2 | 58–64 HRC | — | 27 | High chrome, wear resistant |
| Tool Steel | O1 | 57–62 HRC | — | 65 | Oil hardening, gauges & jigs |
| Tool Steel | M2 | 60–65 HRC | — | 30 | HSS, drill bits & taps |
| Tool Steel | S7 | 54–58 HRC | — | 40 | Shock resistant, chisels & punches |
| Tool Steel | H13 | 44–52 HRC | — | 40 | Hot work, die casting dies |
| Structural | A36 | 119–159 BHN | 58–80 | 72 | Structural, weldable |
| Free Machining | 12L14 | 163 BHN | 78 | 170 | Leaded, best machinability |
Stainless Steels
| Grade | Type | Hardness | Machinability % | Notes |
|---|
| 303 | Austenitic | 160–200 BHN | 78 | Free machining stainless, sulfur added |
| 304 | Austenitic | 170–200 BHN | 45 | Most common, 18-8, food grade |
| 316 | Austenitic | 170–200 BHN | 36 | Marine grade, molybdenum added |
| 410 | Martensitic | 180–220 BHN | 54 | Heat treatable, moderate corrosion resistance |
| 420 | Martensitic | 50–55 HRC | 45 | Cutlery & surgical, higher carbon |
| 440C | Martensitic | 58–60 HRC | 25 | Highest hardness stainless, bearings |
| 17-4 PH | Precipitation Hardening | 35–44 HRC | 48 | Aerospace, high strength with good corrosion resistance |
Aluminum Alloys
| Alloy | Temper | Tensile (ksi) | Machinability | Notes |
|---|
| 6061 | T6 | 45 | Excellent | Most common, good all-around |
| 7075 | T6 | 83 | Good | Aerospace, very high strength |
| 2024 | T3 | 70 | Good | Aircraft skins, fatigue resistant |
| 5052 | H32 | 33 | Fair | Marine, good weldability & corrosion resistance |
| 6063 | T6 | 35 | Good | Extrusions, architectural |
| MIC-6 | Cast | 25 | Excellent | Cast plate, very stable, fixture plates |
Other Metals
| Material | Hardness | Machinability | Notes |
|---|
| Brass C360 | 78 HRB | Excellent (100) | Free cutting brass, the machinability baseline |
| Bronze C932 (SAE 660) | 65 HRB | Good (50) | Bearing bronze, self-lubricating |
| Copper C110 | 40–50 HRB | Fair (20) | ETP copper, gummy — use sharp tools |
| Titanium 6Al-4V (Grade 5) | 36 HRC | Poor (22) | Most common Ti alloy, aerospace, low speed & rigid setup |
| Inconel 718 | 36–44 HRC | Very Poor (12) | Nickel superalloy, work hardens, ceramic inserts recommended |
| Monel 400 | 110–185 BHN | Poor (18) | Nickel-copper, marine & chemical, work hardens |
Plastics
| Material | Tensile (ksi) | Machinability Notes |
|---|
| Delrin / Acetal (POM) | 10 | Excellent machining, very stable, sharp tools, high speed |
| Nylon 6/6 | 12 | Good machining, absorbs moisture — may swell |
| UHMW-PE | 5.8 | Flexible, tends to deflect — use light cuts, sharp tools |
| PTFE (Teflon) | 3.9 | Very soft, cold flow under load, use very sharp tools |
| Polycarbonate | 9.5 | Chips well, can crack if stressed — avoid coolant on edges |
| ABS | 6.5 | Good machining, melts at low temperatures — moderate speed |
| G10 / FR4 | 45 | Fiberglass, extremely abrasive — use carbide or diamond tooling, dust hazard |
Material Hardness Conversion
| HRC | HB (Brinell) | HV (Vickers) | Tensile (approx ksi) |
|---|
| 20 | 226 | 238 | 106 |
| 25 | 253 | 266 | 120 |
| 30 | 286 | 302 | 138 |
| 35 | 331 | 350 | 160 |
| 40 | 371 | 392 | 180 |
| 45 | 421 | 446 | 208 |
| 50 | 481 | 513 | 242 |
| 55 | 546 | 587 | 280 |
| 60 | 613 | 697 | 320 |
| 65 | — | 832 | — |
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