Identifying The Tensile Strength of Grade 5 VS Grade 8

Have you an Automotive, Industrial Machinery, Valves, Motors, or any heavy applications? But won’t reach the final decision and have confusion on which grade bolts need to be used. In which matter do you need to be more concerned? Here you get a clear concept of which bolts you should use for your applications.

Grade 5 bolts are commonly used in automotive applications or require medium tensile strength and offer 105,000 and 120,000 psi with three radial lines. Grade 8 Bolt is generally used in Industrial Machinery, Valves, Motors, or any heavy applications or requires high tensile strength and offers 150,000 psi with six radial lines.

When you distinguish Grade 5 and Grade 8 with their specific manner, you become sure they perform better in the sector. So here, I try to discuss their exclusive character and use the area.

Comparison Table of Grade 5 & Grade 8

CategoryGrade 5Grade 8
MaterialMedium Carbon SteelMedium Carbon Alloy Steel
RustProtective Protective 
Tensile Strength105,000 to 120,000 PSIUp to 150,000 PSI

Details Comparison: Grade 5 VS Grade 8

Here I try to compare the two grades in detail. You would be able to get a deep thought and quickly identify the best one. According to your needs, choose the best one following these specific criteria.


Almost grade 5 bolt is made from carbon steel which ensures the durability of the screw. Carbon makes the screw structure strong and increases stability for long-lasting. So for the rough use and durable frame, Grade 5 is a more reliable fastener with torque.

Grade 8 bolts are used the more pure carbon steel and make the body structure strong. So for the material issues, Grade 8 has sufficient value to compare with any grade bolts. Using carbon steel ensures the sustainability and yield strength of the screw.


In grade marking 5 there not use pure steel; instead used a mix of carbon. That’s why it wouldn’t play in a challenging position.

As a result, increase the structural flexibility and reliability of your application. Grade 5 is used more in local shops to repair bolt grade for flexible content.

The Grade 8 flexibility is not good as other grades. Because here emphasis on the tensile strength. So for the flexibility, here have a little gap in Grade 8. Otherwise, it would be ok. It depends on your application’s demands.


In any weather, the carbon steel helps you get rid of rust problems for a long time. Generally, in the rainy season, rust increases and loss of the temper of the screw. Grade 5 fastener uses carbon and is galvanized with Zinc, which protects your fastener from rust.

Grade 8 is coated with Zinc Platting or hot-dip galvanizing. That’s why it would be safe from the rust. Even in the rainy season, the bolts would secure and survive for a long time. So here have no tension on rust to use in external applications closely related to water.


Grade 5 offer in yield stretch about 92,000 lbs / in2 x .03349 in2, minimum 3081 lbs and tension failure about 120,000 lbs / in2 x .03349 in2, minimum 4019 lbs.

Grade 8 offers a huge yield stretch about 130,000 lbs / in2 x .03349 in2, minimum 4354 lbs and also offer a massive tension failure about 150,000 lbs / in2 x .03349 in2, minimum 5024 lbs.


Here the price is under control. So for your medium applications, you can easily afford the higher Grade 5. If their light applications, then keep in mind the Grade 8 price.

Generally, Grade 8 offers more strength and use for heavy industrial machinery assessment. That’s why the price is high than the others. So it’s a fundamental matter to keep in mind when wanting to use Grade 8.

Comparison Result

After a lengthy discussion, I try to compare the two Grades, 5 & 8. It would be easy to understand the Pros and Cons and have an overview of the specific features.

In their position, they bear their best value. They compare the features of the two, then easy to judge our introduction questions. Let’s look at the comparison session Grade 5 VS grade 8.

Material: Both are passed. So you can choose your needs.

Flexibility: Here, Grade 5 is in a good position than Grade 8.

Rust: Both played equally. So it’s up to you.

Capacity: Certainly, Grade an 8 is better than Grade 5

Price: Generally, the Grade 5 price is lower than the Grade 8

NOTE: It’s just a contradictory fact to explore the central theme of Grade 5& 8. According to your application demand, you can choose the best one. Because no one would complement each other, and it’s not right to abuse.

Grade 5 Bolts

Grade 5 is made with medium Carbon Steel hardened for strength and flexibility with corrosion resistance. Three radial lines distinguish it with durability.

Even it promises tensile strength of 105,000 to 120,000 PSI. In automotive applications offering medium strength, use the grade 5 bolts more. ¼ to 1 ½ is a more familiar Grade 5 bolt head figure.

Grade 5 bears the medium strength and maintains an excellent value for your medium-range metal connector. Also, Grade 5 fasteners use a vast amount per day and quickly find any local material shop.

Moreover, it is made from steel, Titanium, Plastic or Exotic metal. Today it is available with a different coating. Here I use some parameters to measure the strength of Grade 5 and why it has become a reliable fastener.


  • Easy to adjustable anywhere
  • Affordable 
  • Powerful backup
  • Water resistance


  • Only designed for medium strength

Grade 8 Bolts

High strength bolts with six raised dashes in Grade 8 fastener. Tempered with medium carbon steel which would increase the sustainability of bolts. An impressive tensile strength offer about 150,000 PSI which is the highest range of all grade. 

Even we can say it would be enough to support two medium-grade bolts. In Industrial Machinery, Valves, Motors, or any heavy applications permit the Grade 8.

So, Grade 8 generates more tensile strength and a more reliable fastener than ever. Generally, it would make from solid materials and used in heavy industries.

That’s why its strength recovery can get any grade bolts. Here I also use some parameters to judge the Grade 8 as a reliable fastener.


  • Have a strong material structure
  • Adjust at any weather 
  • Offer a massive tensile strength
  • Usable in heavy machinery


  • Flexibility is not good at all
  • More expensive

Why Need to Know About 5 & 8 Grade?

For our daily needs, we use these two bolts more. But we fall in confusion about where to use the perfect grade bolts. Grade bolts are used in different spheres of life to connect two objects strongly.

In that case, use the grade bolts according to actual need. You can use higher-grade bolts where you need heavy or the most powerful bolt. But in lower conditions, it does not need to use. Here you can use low-grade bolts.

So, first, you must know what bolts you need to use. Then it would be easy to use the suitable grade of bolts. As a result, you can use the bolts in the right place. It will also save your money and energy and increase the item’s sustainability.

To reduce the abuse of 8 & 5-grade bolts, you must know about your need. Then use the perfect grade bolts. Otherwise, it would waste money and be unsuitable for your mother’s item. I influence you not always to use high-grade bolts but rather use various grade bolts for more strength.

Bolts Tensile Strength With American Sae Grades

Here are different types of bolts in SAE, which determine the tensile strength of the bolts. You can choose the bolts with maximum tensile strength according to your appliance. So I try to focus on some related grade bolts with their tensile stress range.

Grade 2: These bolts lack marking and are generally used in lower applications. That offers the range between 60,000 to 74,000psi.

It can be partially or entirely coarse thread. These bolts employ in no-critical joints, OEM and maintenance, etc. The standard size is ½ to 4 inches described by mechanical properties and automotive engineers.

Grade S: This grade is specially made for high strength and durability. Withstand stresses ranging between 45 to 49.9 MT per 6.45cm3. Ultimately for heavy metal joints, these markings metric bolt use more.

Determine Bolts Grade

If you know how to determine the different grades of bolts, it would be easy to buy. So to increase your bolts concept, the bellows technique will be more helpful. Carefully focus on the points.

Grade 2: In Grade 2, there are no marks on the head, and made with the most common steel fastener.

Grade 5/F: In Grade 5 or F, three evenly spaced radial lines in the head can use as their complement.

Grade 8/G: In Grade 8or G, there has five evenly spaced radial lines in the head and replaced by one another.

People Often Ask More

Is Shear Easier of Grade 5 & Grade 8?

There are myth that grade 5 is share easier than grade 8. But it’s not right. Actually the shear strength of the carbon steel about 60% of its ultimate tensile strength and not minimum tensile strength.

Can I Use Grade 8 Anywhere?

No. Grade 5 offers a massive tensile strength but is not suitable for light applications. Otherwise, it would cost because of damage and won’t earn the accountability.

Is Grade 5 best for uses?

It depends on your application need. If there need light or medium support, you can use Grade 5 easily. But when you need massive tensile strength, you should not use it by square inch.

How Stronger Is Grade 8 Than Grade 5?

Grade 8 is the highest range of SAE bolts. ASTM- A325 is equivalent to Grade 5, but on the other hand, Grade 8 is equal to ASTM- A490. So, it’s clear how strong Grade 8 is.

Is Grade 5 Stronger than Stainless Steel?

Of Course, the stainless steel is simply weaker than Grade 5. But if you compare with Grade 2 then it will be ok. So, for the stronger question, Medium Alloy Carbon Steel is better than Stainless steel fasteners.

Final Thought: Who Will Win The Race?

Hopefully you have got a clear concept on Grade 5 VS Grade 8. It would be easy to justify them both according to their features. 

Even also, get a brief overview of the pros and cons. So, we can say. Grade 8 is better than the Grade 5 quickly. If you judge the contribution of two with their level playing field, you can understand both perform equally and bear their value with alloy steel.

So no one can take another’s place and won’t fulfill the essential demand. So, make your decision according to your application need. If you have medium strength, use Grade 5, but for heavy power, use Grade 8. If face any unexpected issue, you can conduct an expert.

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