ASTM A325 and SAE J429 grade 8 are not the same fastener. As a matter of fact, they couldn’t be more different. SAE (Society of Automotive Engineers) establishes specifications covering fasteners intended for use in automotive, OEM, and equipment applications, while ASTM (American Society for Testing and Materials) provides specifications for construction fasteners. There are several differences between these two bolts, including chemistry, strength, application, and dimensional tolerances.
Strength Differences
A325 bolts are typically manufactured from a medium carbon steel (although they can be made from an alloy) while SAE grade 8 bolts are made from a medium carbon alloy steel. Grade 8 bolts are significantly stronger than an A325. An ASTM specification with similar strength properties to grade 8 is ASTM A490.
| Grade | Nominal Size | Proof Load Min (ksi) | Yield Strength Min (ksi) | Tensile Strength Min (ksi) | Rockwell Hardness Min | Rockwell Hardness Max |
|---|---|---|---|---|---|---|
| ASTM A325-1 | 1/2" - 1" | 85 | 92 | 120 | C24 | C35 |
| 1-1/8" - 1-1/2" | 74 | 81 | 105 | C19 | C31 | |
| SAE J429 Grade 8 | 1/4" - 1-1/2" | 120 | 130 | 150 | C33 | C39 |
Compare more strengths with our strength by grade chart.
Configuration Differences
ASTM A325 bolts are heavy hex structural bolts and used in structural steel connections, while SAE grade 8 bolts are finished hex bolts and typically used in automotive and equipment applications. By nature, an SAE bolt is also a more precision fastener with tighter tolerances than an ASTM bolt.
Mechanical properties for A325 bolts under the new F3125 specification are the same for all diameters. Under the original A325 specification, mechanical requirements change for diameters above 1″.
Could you please advice if i can use Grade 8 washer for A 193 B7 grade bolts
@Deniz- A193 does not specify a washer, but the industry typically supplies an ASTM F436 washer. We are not familiar with any grade 8 washers.
Could you please advice what is the diffrence between Grade 8 and 8.8.
@Deniz- The cost difference will depend entirely on the specifics of what you are looking for. There are too many variables to get you a generic price difference.
IS it typical to zinc electroplate Grade 7 Bolts that are head stamped Special BB. I am a plater and have been requested to strip and re-plate this material in a ROHS approved zinc and passivate coating and am concerned on whether or not it requires a bake for embrittlement relief. The new ASTM F1941-15 standard for fasteners does not require a bake for anything under Rc39 however if > than Rc 39 then a 14 hour bake is required between 375 and 400 deg. Fahr.
@Alepi- ASTM F1941 does not require baking of A193 B7 bolts. However, both F1941 and B633 are referenced within A193, and B633 does require baking. I would confirm the plating specification with your customer.
I’m just a farmer in NC who found some steel C channel (8″, 12″) on Craigslist and building a tractor shed 50 x 100 and saw on Ebay all these bargain A325 bolts I can get. Just giving some additional info here.
Are those bargan A325 type 1 galvanized bolts you see on Ebay any good? You see some sellers selling generic A325 bolts made in Taiwan in quantities of 50 to 100 to 300 pcs at good cheap prices. Tool Outlet is one seller comes to mind on Ebay and sells alot of these bolts in these quanities. More quantities, the better the price.
@Danny- There are millions of imported A325s in the marketplace, not only on Ebay and the like, but also at reputable fastener distributors. Just because they are imported does not mean they are not of high quality. That said, I can’t say where the ones you are finding were made, and there are likely some bad ones out there as well. If quality is a concern, I’d make sure that the bolts come with test reports, that way you can be reasonably sure that they are manufactured and tested per ASTM standards.
If in bolt description is indicated GRADE 8 only, does it mean that this bolt related to SAE J429 and not to any other standards?
@Kairat- Yes, if grade 8 is the only call out or marking, then I’d assume J429 is the only standard being referenced.