Ultimate tensile strength chart
Ultimate tensile strength (UTS) for common engineering materials, the maximum stress a material carries before it breaks. Read it alongside yield strength to see how much margin a material has between first yielding and final fracture.
Ultimate tensile strength
| Material | UTS (ksi) | UTS (MPa) |
|---|---|---|
| Structural steel (A36) | 58 | 400 |
| Steel 1045 | 91 | 627 |
| Alloy steel 4140 (Q&T) | 156 | 1075 |
| Stainless steel 304 | 73 | 505 |
| Stainless steel 316 | 75 | 515 |
| Aluminum 6061-T6 | 45 | 310 |
| Aluminum 7075-T6 | 83 | 572 |
| Titanium Grade 5 | 138 | 950 |
| Copper | 32 | 220 |
| Brass | 50 | 345 |
| Bronze | 55 | 380 |
| Cast iron (gray) | 30 | 207 |
| Magnesium (AZ31) | 37 | 255 |
| Nylon 6/6 | 12 | 83 |
| ABS | 6 | 41 |
UTS is the peak of the stress-strain curve. Ductile metals stretch and neck down well past yield before reaching it, while brittle materials like cast iron break near their tensile limit with little warning. Design normally keeps working stress below yield, using UTS to judge the safety margin to fracture.
Want yield strength or the full comparison?
See the Yield Strength Chart and the Material Properties Comparison.
UTS vs yield strength
Yield strength is where a material starts to deform permanently; ultimate tensile strength is where it finally breaks. The gap between them is a measure of ductility and reserve: a wide gap, as in mild steel, means the part visibly deforms and gives warning before failure, while a narrow gap, as in hardened or brittle materials, means failure is sudden.
How UTS is measured
A sample is pulled in a tensile test until it fractures, and the highest load divided by the original cross-section gives the UTS. Past this point a ductile sample necks and the load falls until it snaps. Because it is a single repeatable number, UTS is widely used to rank and specify materials.
FAQ
What is the difference between tensile strength and yield strength?
Yield strength is the stress at which permanent deformation begins; tensile strength is the maximum stress before the material breaks. Tensile is always higher.
What is the tensile strength of mild steel?
Structural mild steel such as A36 has an ultimate tensile strength around 58 ksi (400 MPa), with yield near 36 ksi.
Should I design to yield or tensile strength?
Usually to yield, so the part never permanently deforms. Tensile strength sets the ultimate margin to fracture, applied through a factor of safety.