Carriage Bolts manufactured in A2 Stainless Steel (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70) are dimensioned to DIN 603. The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.
Why Choose A2 Stainless Steel for Carriage Bolts
The most common stainless group for indoor and general outdoor fasteners. For carriage bolts, this matters when good general corrosion resistance is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70 |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| Corrosion characteristic | Good general corrosion resistance |
Corrosion Behavior in Service
A2 (304) gives excellent atmospheric and most-water corrosion resistance and is the most common stainless for Carriage Bolts in indoor and general outdoor service. In chloride-bearing environments (marine air, road salt, swimming pools) consider stepping up to A4 (316).
Comparable Grades
For Carriage Bolts, the alternative stainless grade is A4 (316). The practical dividing line is chlorides: A2 (304) is fine until salt is involved, and A4 (316) exists for the cases where it is — coastal, marine and road-salt service. Neither reaches the strength of a plated class 8.8 or 10.9 fastener.
Using Stainless Fasteners in Aluminum
Stainless steel is more noble than aluminum, so with an electrolyte present — rain, condensation, salt spray — the aluminum becomes the anode and corrodes at the joint. Area ratio decides how bad it gets: a small stainless fastener in a large aluminum section is normally acceptable, a large stainless fastener in thin aluminum is not. Where the joint gets wet, isolate the metals with a coated or nylon washer and a sealant, or specify an aluminum or coated fastener instead.
Sizes of Carriage Bolts Available in A2 Stainless Steel
| Size | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Square neck width (mm) | Square neck depth (mm) | Common length range (mm) | Reference standard |
|---|---|---|---|---|---|---|---|
| M5 | 0.8 | 13.0 | 3.0 | 5.0 | 2.5 | 16~80 | DIN 603 / ISO 8677 |
| M6 | 1.0 | 16.0 | 3.5 | 6.0 | 3.0 | 16~120 | DIN 603 / ISO 8677 |
| M8 | 1.25 | 20.0 | 4.5 | 8.0 | 4.0 | 20~160 | DIN 603 / ISO 8677 |
| M10 | 1.5 | 25.0 | 5.5 | 10.0 | 5.0 | 25~200 | DIN 603 / ISO 8677 |
| M12 | 1.75 | 30.0 | 7.0 | 12.0 | 6.0 | 30~240 | DIN 603 / ISO 8677 |
| M14 | 2.0 | 35.0 | 8.0 | 14.0 | 7.0 | 40~260 | DIN 603 / ISO 8677 |
| M16 | 2.0 | 40.0 | 9.0 | 16.0 | 8.0 | 40~300 | DIN 603 / ISO 8677 |
| M20 | 2.5 | 50.0 | 11.0 | 20.0 | 10.0 | 50~300 | DIN 603 / ISO 8677 |
Dimensions are independent of the material: every size above is available in A2 Stainless Steel.
Custom manufacturing · Made to drawing
Need this bolt in a grade that is not listed?
A2 Stainless Steel is one of the grades the catalog describes. A non-standard bolt is quoted from the drawing; where one already exists in the catalog, the special is usually a variation on its tooling. Made by cold heading or hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
