Material Properties Database

This table compares typical room-temperature properties for the metals most often specified in CNC machining, sheet metal fabrication, and additive work: aluminum, steel, stainless steel, titanium, brass, and copper. Use density to compare weight, tensile and yield strength to compare strength, and elongation to compare ductility and formability. The values are typical ranges that shift with temper, form (bar versus sheet), and supplier lot, so treat them as a starting point for material selection rather than a substitute for the certified results on a material test report.

How to use this table

• Density (g/cm3) estimates part weight. Aluminum sits near 2.7, titanium near 4.4, and steels near 7.8 to 8.0, so an aluminum part of the same volume is roughly one third the weight of a steel one.
• Tensile strength (MPa) is the stress at which a metal breaks; yield strength (MPa) is the stress at which it stops springing back to shape and bends permanently. For most machined and formed parts, yield is the more useful limit, because staying below it keeps the part from taking a permanent set.
• Elongation (%) is the stretch before break, and it tracks ductility and formability. Higher elongation means the metal bends and draws more before cracking; lower elongation means it is stiffer but more likely to crack under forming.
• Where a standard sets a floor, the table lists that minimum and labels it. The 304 and 316 rows show ASTM A240 minimums for tensile, yield, and elongation; the A36 row shows the specification minimum yield. Everywhere else the entry is a typical range, because real properties move with temper and lot.

Comparing metals by property

Weight and strength-to-weight

• Lightest: aluminum (about 2.7 g/cm3) and titanium (4.43 g/cm3) are far lighter than steel (about 7.85 g/cm3) or stainless (8.00 g/cm3). When weight is the constraint, aluminum or titanium wins.
• Strongest by weight: titanium Ti-6Al-4V (Grade 5) has the best strength-to-density ratio here, with tensile up to 1105 MPa at 4.43 g/cm3. Among aluminum alloys, 7075-T6 reaches 572 MPa tensile at 2.81 g/cm3.

Absolute strength, ductility, and machinability

• Strongest in absolute terms: titanium and 7075-T6 also lead on raw tensile and yield. Medium-carbon 1045 (550 to 690 MPa tensile) is the strongest common carbon steel listed.
• Most ductile and formable: stainless 304 and 316 (40 percent or more elongation), brass C260 (40 to 65 percent), and copper C110 (up to 55 percent) stretch the most before breaking, which is why they bend, draw, and spin so well.
• Most machinable: brass C360 is the free-machining benchmark (rated 100% machinability, the reference against which the others are rated), followed by the aluminum alloys. Stainless work-hardens and machines slowly; titanium and copper build heat at the tool and call for slower cuts and sharp tooling.

Choosing a metal for a part

Match the metal to the process and the load, not just to a single property number.

Forming and machining choices

• Sheet metal bending: aluminum 5052-H32 is the formable choice (12 to 20 percent elongation, low springback), while 6061-T6 needs overbending to offset 5 to 10 degrees of springback. Avoid bending 7075-T6, which tends to crack at the bend line. Stainless 304 and 316 bend well but spring back more than mild steel.
• CNC machining: 6061-T6 machines cleanly and holds tolerance, 1018 is the common low-carbon steel for shafts and pins, and 1045 suits higher-strength parts that take hardening.

Structural, weight-critical, and conductive choices

• Structural and plate: A36 is the standard structural carbon steel (250 MPa minimum yield) for baseplates, brackets, and frames.
• Weight-critical or corrosion-critical: titanium brings strength plus corrosion resistance at low weight; choose 316 over 304 only where chlorides or marine exposure justify the roughly 15 to 30 percent cost premium.
• Conductive: copper C110 carries current for busbars and conductors (the highest conductivity of common coppers), and brass C360 suits connectors and hardware that machine easily.

Limitations and how to verify

Every value here is a typical figure, not a certified result for a specific lot. The same alloy changes with temper (T6 versus O, H32 versus H34), with form (bar versus sheet versus plate), and from one supplier lot to the next. For a real part, request the material test report for the specific heat, which lists chemistry and mechanical results traceable to the lot number. Do not treat any single table value as a design limit; confirm against the governing standard (such as ASTM A240 for stainless plate) before finalizing a specification.