Threaded 101: Materials

EDUCATIONAL SERIES

Materials

Welcome to the third installment of our Threaded Rod 101 series. This post provides an overview of the materials used to produce threaded rod as well as which materials work best for certain applications. Read our previous post to get a synopsis of our threaded rod educational series.

Materials

The most common material for threaded rod is steel, spanning a variety of alloys, strengths, and hardness. Steel threaded rods can be coated or uncoated, with zinc being a common coating for electro-plated and hot-dip galvanized threaded rod. Other common metallic materials used to make threaded rod include aluminum, brass, copper, and silicon bronze. Additionally, non-metallic materials such as plastic, nylon, and synthetic rubber can be used to make threaded rod. This post will only go into details for metallic materials.

Threaded rod materials are classified according to “tensile strength”—the degree of resistance to breaking under tension. Additionally, there are various specifications for steel grades, including ASTM, AISI, and SAE International.

"Not all threaded rod is created equal."

Depending on the application and industry, certain materials are preferred. For high-temperature applications, Grade B7 steel is in high demand because of its tensile strength, excellent heat resistance and resistance to corrosion.

Throughout the industry, there are several different materials and grades to choose from. All America Threaded Products only carries threaded rod produced from metallic materials. Materials for threaded rod are listed below, starting with steel rod types and finishing with other metals.

Steel Threaded Rod Grades

Low Carbon Steel

Low carbon steel is the most common material throughout the threaded rod industry due to its versatility. There are different grades of low carbon steel to meet the minimum tensile and yield strength requirements of ASTM A307 including 1008, 1018, & 1022. Our mild steel certificate shows the varying chemical composition limits of each grade. Low carbon steel is easy to shape because of the malleability of the metal. This makes it the ideal material for bending and manufacturing products such as U-bolts. The material is also used across a variety of industries because of its weldability.

F1554

F1554 is a specification covering bolts designed to anchor structural supports into concrete foundations. There are three grades of F1554, each with increasing yield strengths correlating to their grade names. These grades include Grade 36 with a yield strength of 36 ksi, Grade 55 with a yield strength of 55 ksi, and Grade 105, which is a high-strength alloy with a yield strength of 105 ksi. F1554 bolts can be headed bolts, straight anchor rod bolts, or bent L-anchor bolts.

ASTM A193/B7

Due to its high tensile strength, B7 is one of the strongest materials in the industry. It is a grade of the spec A193 (Chromium Molybdenum). B7 achieves its strength through a heat-treating process where it is quenched and tempered at 1150 degrees F. It is preferred in industries and jobs where high temperatures and high pressures are reached such as in pressure vessels and valves in the oil and gas industry. B7 is one of the strongest materials that AATP carries for threaded rod.Hot-dip galvanizing is the process of dipping steel products into a kettle or vat of molten zinc. This finish provides excellent protection against corrosion and rust when used in outdoor applications such as street lights, signs, and on offshore drilling rigs or projects where salt spray is present. Considerations about hole sizes, over-tapping and thread recesses, and dissimilar metals in contact must be taken when using hot-dip galvanized threaded parts.

SAE J429- Grades 2, 5, & 8

SAE J429 comes in three grades: Grades 2, 5, and 8. Grade 2 is the most common and includes low or medium carbon steel bolts.  Grade 5 is made of medium carbon steel which is quenched and tempered at 800 degrees Fahrenheit (F). This is one of the stronger materials and is more heat resistant than low carbon steel; though it is still not as strong as B7 or Grade 8. This material is typically used for headed bolts and is primarily used in the automotive industry. The ASTM equivalent to Grade 5 would be ASTM A449.

Grade 8 is a medium carbon or alloy steel, and has one of the highest tensile strengths available, even higher than B7. It is also quenched and tempered at 800 F leading to its strength. The preload, or thread tension in a fastener is higher when the type of steel being used is grade 8 in quality. Grade 8 is typically used for threaded bolts in demanding applications such as automotive suspensions for large trucks and tractors.

ASTM A449

A449 is manufactured from a medium carbon or alloy steel that develops its mechanical values through a heat-treating process. ASTM A449 is medium strength and is typically used in engineering applications. Anchor bolts are a common product made with this material and are often used in the construction industry.

Stainless Steel Threaded Rod Grades

304 SS

Stainless Steel 304 is a type of stainless steel consisting of at least 18% chromium and 8% nickel, as well as up to 0.08% carbon. This is the most common of the 300 series stainless steels.  Thanks to the chromium content, it is resistant to oxidation and corrosion. Due to the high corrosion-resistant properties, it is used in the appliance industry for its aesthetically pleasing appearance.

316 SS

Stainless Steel 316 is a highly corrosion-resistant stainless steel similar to 304SS. This is one of the highest grades of “common” stainless steel. In addition to chromium and nickel, 316 SS also contains molybdenum which helps in the resistance of chlorides (for example: salts). Stainless Steel 316 is commonly used for projects in the marine environment where salt water is involved.

18-8

18-8 is a term that gets its name from the 18% chromium and 8% nickel content. 18-8 is not a grade that is typically used to call out fasteners made from 300 series stainless steel, which have varying levels of this mixture. 18-8 series fasteners are used to prevent rust in applications where moisture is constant, like breweries.

ASTM A193/B8

B8 bolts are manufactured from 304 SS. This material is non-magnetic and offers good corrosion resistance. There are two classes within this material. Class 1 carries a tensile rating of 75,000 PSI, and Class 2 is strain-hardened and has an increased tensile strength of up to 125,000 PSI.

ASTM A193/B8M

B8M is comparable to B8. The difference between B8M and B8 is that B8M has added Molybdenum. B8M is manufactured from 316 SS making it more corrosion resistant than A193 B8. There is a class 1 and class 2 B8M. Class 2 is strain-hardened, increasing the tensile strength to 90,000-125,000 PSI depending on the diameter.

Other Metal Threaded Rod Grades

Brass

Brass is a metal alloy made up of copper and zinc. More importantly, brass is easy to manufacture and corrosion-resistant. Brass typically has a bright, gold-like appearance that makes it desirable for certain projects like plumbing and electrical applications that are visible.

Aluminum

Aluminum is a lightweight, chemically stable metal that is naturally corrosion-resistant. Aluminum is known for being a soft, non-magnetic, metal that is easily formed. Due to its light weight, it is commonly used for threaded products in the aviation industry.

Silicon Bronze

Silicon Bronze is composed of roughly 96% copper and is a low-lead brass alloy. Surface finish, high strength, and superior corrosion-resistant properties make it attractive to the electrical, marine, and energy industries.

At All America Threaded Products, we use the following materials for our threaded products:

• Low Carbon Steel
• F1554 Grade 55 (S1 supplement)
• ASTM A193/B7
• Grade 8
• T304 Stainless Steel
• T316 Stainless Steel
• Brass
• Aluminum
• Silicon Bronze

Need something you don't see here? Contact your sales representative.

Application is key when determining which material to use for your project. As you can see, different materials are used based on the environment and tension load.  With so many materials options, the threaded industry has thousands of products to choose from. The materials listed above are commonly used materials throughout the threaded rod industry.