Strain-Hardened Stainless Fasteners
Nickel Systems has few strain-hardened hex bolts and hex nuts in stock. Most strain-hardened fasteners are supplied on a made to order basis.
The advantage of strain-hardened stainless fasteners is greater strength with equivalent corrosion resistance. Strain-hardened parts have the same chemistry as their non-strain-hardened counter parts. Generally, a strain-hardened stainless bolt has the same strength as a Grade 5 steel bolt. Cold working a larger diameter bar into a smaller diameter bar is the usual method used to obtain the strain-hardened properties. Excessive heat will destroy the strain-hardening. 304 and 316 Stainless are the two most common materials that are available, which have undergone this process. Other austenitic stainlesses can be subjected to strain hardening, however, the raw material is subject to limited availability.
ASTM A193 Grade B8 Class 2 (304 Stainless Bolts)
ASTM A193 B8M Class 2 (316 Stainless Bolts)
ASTM A194 Grade 8 Class 2 (304 Stainless Nuts)
ASTM A194 Grade 8M Class 2 (316 Stainless Nuts)
Typical Tensile Strength (at room temperature in KSI)
Typical Chemistry (% by weight)
304: C .02, Cr 18, Fe 71, Mn 1, Ni 8, S .01, Si .5, P .02
316: C .02, Cr 17.5, Fe 68, Mn 1, Mo 1.5, Ni 10.5, S .01, Si.5, P .02
This video provides a very basic explanation of strain-hardening.