Class 10.9 Bolts That Must Pass Salt Spray: Test the Samples You Already Have

Short answer: Class 10.9 strength plus a salt spray requirement is an unusual combination, and it costs more than either one alone. If you already have cheaper samples from other suppliers, test them against the same requirement before you decide on price. In this case, neither of the two samples we tested passed.

The case: 10.9 with a salt spray test

A customer messaged us asking for parts in property class 10.9 that also had to pass a salt spray test. We told them plainly: very few parts of this kind are made in 10.9 with a salt spray requirement. We could do it, but it would cost more.

Then we asked them to send us the samples they had from their other suppliers, so we could test them for them.

The result

The customer sent samples from two other suppliers. We tested them against the requirement, and neither met it. The customer then visited our factory and placed an order within a week.

The test did the persuading. A sample that does not meet the requirement is not a cheaper version of the same part.

Why the combination is hard

• Class 10.9 is a high-strength steel. Electroplating it brings a hydrogen embrittlement risk that has to be handled in the process and on the drawing.
• Salt spray resistance depends on the coating and its thickness. The hours are set by your requirement, and the supplier confirms what the chosen coating can reach.
• Both have to pass on the same part. Hardness and salt spray are tested separately, but the part has to meet both.

What to send with the inquiry

1. Property class, and the hardness range if your drawing gives one.
2. Coating type and thickness.
3. Salt spray hours, the test method and the acceptance criterion, such as no white rust or no red rust.
4. Any samples you already have, so they can be tested against the same requirement.

If you need high-strength fasteners with a corrosion requirement, send the requirement and any samples through our RFQ form. We will test the samples before we talk about price.

Related: plating high-strength bolts and hydrogen embrittlement · pre-shipment inspection for custom fasteners

How this was written: the case comes from an interview with our general manager about past orders. The salt spray hours in this case are not given, because they depend on the coating chosen. The customer is not named.