ISO 3506 Stainless Steel Fastener Grades Explained: A2 vs A4 Guide
At Webber Crimpex we meet many customers who get confused when they see labels like A2 50 or A4 70 on stainless steel fasteners. They usually ask us one simple question. Which one should I use. So we decided to break down the ISO 3506 stainless steel fastener grades in a way that anyone can follow. So in this complete guide our Webber Crimpex team explains everything in simple words. We work with stainless steel every day so we want you to understand which grade suits your job. Because of this, we will explain where each grade performs well how the material behaves and how you can choose the right fastener without guesswork.
What ISO 3506 Stainless Steel Fastener Grades Mean
The ISO 3506 stainless steel fastener grades system helps users understand stainless steel types and strength values. Many buyers know the names A2 and A4 but they do not fully understand the difference. So we break the entire system into two parts. First is the material type. Second is the strength level. These grades help you select the right fasteners for machines construction work outdoor fittings and marine jobs. As a result you avoid corrosion issues and joint failures.
Material Types in ISO 3506 Stainless Steel Fastener Grades
The first part of ISO 3506 stainless steel fastener grades focuses on the material. When you see A2 or A4 you are looking at the chemical composition. A2 is similar to 304 stainless steel. It works well in many indoor and outdoor projects where the environment is not very harsh. A4 is similar to 316 stainless steel. It has molybdenum added. This makes it stronger against rust saltwater and chemicals. Because of this A4 performs well in coastal areas and chemical industries.
A2 Stainless Steel
A2 stainless steel for most general jobs because it works well in buildings simple machines outdoor fittings and many factory setups. It is reliable strong enough for daily use and easy for teams to work with. Although A2 is not the strongest material it offers good corrosion resistance. It holds up well in humid or rainy areas. It also gives stable performance with general loads. So when you work on anything that requires clean looks moderate strength and stable quality A2 is a safe choice.
A4 Stainless Steel
A4 stainless steel stands at a higher performance level within ISO 3506 stainless steel fastener grades. It contains molybdenum that improves corrosion resistance in salty and chemical environments. Because of this A4 is used in marine sites chemical plants and food processing systems. A4 does not react easily with acids. It also handles moisture heat and cleaning chemicals better than A2. So whenever you need long life durability and tough protection you select A4 stainless steel.
Strength Classes in ISO 3506 Stainless Steel Fastener Grades
After understanding material types you need to look at the numbers in ISO 3506 stainless steel fastener grades. You will find grades like 50 70 and 80. These numbers show the tensile strength. Higher numbers mean higher strength. So A4 80 is stronger than A4 70. Similarly A2 70 is stronger than A2 50. This simple numbering system helps you match fasteners with load conditions machine pressure and joint requirements.
A2 50 Strength Level
A2 50 sits at the lower strength side in ISO 3506 stainless steel fastener grades. It works well in light applications. You can use it for small brackets electrical panels normal machine parts and household fittings. Although it is not suitable for heavy loads it works reliably when the weight or vibration is low. Because of this many installers use A2 50 for basic assembly tasks that need stainless steel but not high strength.
A2 70 Strength Level
A2 70 is one of the most used grades in ISO 3506 stainless steel fastener grades. It gives higher strength compared to A2 50. It also keeps the same corrosion resistance of A2 material. As a result you can use A2 70 in machines structures conveyor systems and outdoor units. It stays stable under moderate vibration. It handles more stress compared to A2 50. So this grade fits many mid load jobs in industries.
A4 70 Strength Level
A4 70 gives both strength and corrosion resistance in ISO 3506 stainless steel fastener grades. Because of the molybdenum A4 70 withstands salty air chemical splashes and constant moisture. It works well in coastal buildings marine pumps chemical units and pharma equipment. It also fits food machinery that undergoes water cleaning. So A4 70 is a safe choice for long life stable performance and strong joints.
A4 80 Strength Level
A4 80 sits at the top strength level within ISO 3506 stainless steel fastener grades. It offers the best combination of corrosion resistance and strength. Because of this factories use A4 80 for heavy load joints metal structures marine engineering and high pressure systems. Although it costs more it delivers the longest life. It also handles vibration heat and pressure better than all other stainless steel grades in this system.
How to Choose the Right Fastener Grades
Choosing between ISO 3506 stainless steel fastener grades becomes easy when you know the environment and the load. First check if the area has saltwater chemicals or moisture. If yes choose A4. If the area is normal choose A2. Second check the load level. If the load is light choose 50. If the load is medium choose 70. If the load is heavy choose 80. Because of these simple steps you can avoid premature failure and repair costs.
| Grade | Material | Strength | Best Use |
|---|---|---|---|
| A2 50 | 304 steel | Low | Light loads indoor outdoor general work |
| A2 70 | 304 steel | Medium | Machines structures conveyors |
| A4 70 | 316 steel with molybdenum | Medium | Marine chemical food units |
| A4 80 | 316 steel with molybdenum | High | Heavy loads marine engineering |
Why ISO 3506 Stainless Steel Fastener Grades Matter for Industry
Industries trust ISO 3506 stainless steel fastener grades because they offer predictable performance. A factory needs strong joints that do not loosen or rust. A construction project needs fasteners that handle weather and load. A marine company needs hardware that stays solid in saltwater. These grades support safe operations efficient assembly and long product life. Because every grade has a clear purpose industries avoid mismatches.
How Webber Crimpex Delivers ISO 3506 Stainless Steel Fastener Grades
At Webber Crimpex we manufacture nuts bolts and washers that strictly follow ISO 3506 stainless steel fastener grades. We use high quality raw materials and strong testing methods. We also check hardness tensile values and corrosion behavior. Our team supports custom sized fasteners. We help customers choose the right grade for their load environment and budget. Because of this many industries trust our components for long lasting performance.
FAQs
1. What is the meaning of ISO 3506 stainless steel fastener grades?
These grades show the material type and strength level. A2 and A4 show the material and numbers like 50 70 and 80 show strength.
2. Is A4 better than A2?
Yes. A4 has better corrosion resistance. It performs well in marine and chemical areas.
3. Can A2 50 handle vibration?
It handles small vibration but not heavy vibration. For more vibration use A2 70 or A4 70.
4. Where should I use A4 80?
Use it in heavy load marine jobs chemical plants and high pressure systems.
5. Does Webber Crimpex make custom ISO 3506 fasteners?
Yes. We make custom sizes based on drawings and requirements.
