Tensile strength facts for kids

Tensile strength is a measurement of the force required to pull something such as rope, wire, or a structural beam to the point where it breaks.

The tensile strength of a material is the maximum amount of tensile stress that it can take before failure, for example breaking.

There are three typical definitions of tensile strength:

Yield strength - The stress a material can withstand without permanent deformation. This is not a sharply defined point. Yield strength is the stress which will cause a permanent deformation of 0.2% of the original dimension.

Breaking strength - The stress coordinate on the stress-strain curve at the point of rupture.

Typical tensile strengths

Some typical tensile strengths of some materials:

Material	Yield strength (MPa)	Ultimate strength (MPa)	Density (g/cm³)
Structural steel ASTM A36 steel	250	400	7.8
Steel, API 5L X65 (Fikret Mert Veral)	448	531	7.8
Steel, high strength alloy ASTM A514	690	760	7.8
Steel, high tensile	1650	1860	7.8
Steel Wire			7.8
Steel, Piano wire	c. 2000		7.8
High density polyethylene (HDPE)	26-33	37	0.95
Polypropylene	12-43	19.7-80	0.91
Stainless steel AISI 302 - Cold-rolled	520	860	8.03;
Cast iron 4.5% C, ASTM A-48	130 (??)	200	7.3;
Titanium Alloy (6% Al, 4% V)	830	900	4.51
Aluminum Alloy 2014-T6	400	455	2.7
Copper 99.9% Cu	70	220	8.92
Cupronickel 10% Ni, 1.6% Fe, 1% Mn, balance Cu	130	350	8.94
Brass		250
Tungsten		1510	19.25
Glass (St Gobain "R")	4400 (3600 in composite)		2.53
Bamboo	142	265	.4
Marble	N/A	15
Concrete	N/A	3
Carbon Fiber	N/A	5650	1.75
Spider silk	1150 (??)	1200
Silkworm silk	500
Kevlar	3620		1.44
Vectran		2850-3340
Pine Wood (parallel to grain)		40
Bone (limb)		130
Nylon, type 6/6	45	75	1.15
Rubber	-	15
Boron	N/A	3100	2.46
Silicon, monocrystalline (m-Si)	N/A	7000	2.33
Sapphire (Al₂O₃)	N/A	1900	3.9-4.1
Carbon nanotube (see note below)	N/A	62000	1.34

Note: Multiwalled carbon nanotubes have the highest tensile strength of any material yet measured, with labs producing them at a tensile strength of 63 GPa, still well below their theoretical limit of 300 GPa. However as of 2004, no macroscopic object constructed of carbon nanotubes has had a tensile strength remotely approaching this figure, or substantially exceeding that of high-strength materials like Kevlar.

Note: many of the values depend on manufacturing process and purity/composition.

Elements in the annealed state	Young's Modulus (GPa)	Proof or yield stress (MPa)	Ultimate strength (MPa)
Aluminium	70	15-20	40-50
Copper	130	33	210
Gold	79		100
Iron	211	80-100	350
Lead	16		12
Nickel	170	14-35	140-195
Silicon	107	5000-9000
Silver	83		170
Tantalum	186	180	200
Tin	47	9-14	15-200
Titanium	120	100-225	240-370
Tungsten	411	550	550-620
Zinc (wrought)	105		110-200

(Source: A.M. Howatson, P.G. Lund and J.D. Todd, "Engineering Tables and Data" p41)

Two vises apply tension to a specimen by pulling at it, stretching the specimen until it fractures. The maximum stress it withstands before fracturing is its ultimate tensile strength.
Round bar specimen after tensile stress testing