Do Higher Grade Bolts Have Lower Stretching Ability?
Myth: The higher the bolt grade, the lower the stretching ability of the bolt.
Truth: whatever their grade, bolts made from the same material have the same modulus of elasticity E:
- For carbon steel bolts (ISO 898-1): E=210 kN/mm2.
- For stainless steel bolts (ISO 3506-1): E=170 kN/mm2.
According to the law of Hooke, the stretching ability of a material depends on its modulus E while its stress σ and elongation ε are linked as follows: σ=E x ε. Therefore, the higher grade means the same elongation under the same force for the same bolt sizes, but a greater load can be supported before yielding or breaking.
Like this article and want more?
Get engineering and bolting insights delivered straight to your inbox. Subscribe to our insights newsletter now!