Short answer: Yield strength is the stress at which a metal starts to deform permanently; tensile (ultimate) strength is the maximum stress it reaches before breaking. Design is normally based on yield, while tensile sets the safety margin against overload.
At a Glance
The Two Numbers
Yield (Re/Rp0.2) marks the end of elastic, reversible behaviour; tensile (Rm, UTS) is the peak load before necking. Both appear on every mill certificate — see our Mill Test Certificate Guide. The concepts underpin Low Carbon Vs High Carbon Steel and alloy selection.
Yield Ratio & Design
The yield-to-tensile ratio (Re/Rm, often 0.5-0.9) hints at ductility and cold-forming ability; a low ratio means more reserve before failure. Structural grades are compared on yield in S355 Vs S275 Steel e En 10025 Structural Steel.
Why It Matters
Engineers size parts so working stress stays below yield (with a safety factor), using tensile as the overload ceiling. Fatigue life is a separate concern, covered in Metal Fatigue Endurance Limit.
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Perguntas frequentes
Yield is the stress where permanent deformation begins; tensile (UTS) is the maximum stress before fracture. Design uses yield; tensile gives the overload margin.
Yield is the primary design limit — parts are sized to stay below it; tensile strength indicates reserve capacity before breaking.
It depends on use: around 0.5-0.7 for ductile, cold-formable steels; higher ratios indicate stronger-but-less-ductile, higher-strength grades.
Every HXSCO lot ships with a mill test certificate showing yield, tensile, elongation and other mechanical properties per the ordered grade.
Specify Strength with HXSCO
HXSCO supplies steels with full mechanical data on the mill certificate — yield, tensile and elongation to your design spec. Send your grade and requirement for a quote.