A4-70 vs A4-80: Strength, Cold Working and Marine Service Limits
For marine stainless steel fasteners, the property classes A4-70 and A4-80 are defined in ISO 3506-1, covering corrosion-resistant stainless steels. Choosing between them is not simply "80 is stronger is better" — it depends on cold working, chloride exposure, and how the fastener is manufactured. This article explains what each class actually guarantees and when one is preferred for marine service.