There are a wide variety of fasteners available, and understanding the differences between the steel types used to make them is one of the most important decisions you'll make for any project. In this article, we look at the main steel types used to make nuts and bolts — and their pros and cons.

Bolt-In Co is located on Wises Rd, Maroochydore on the Sunshine Coast. In-store and online, we offer a wide range of high-quality nuts, bolts, fasteners, and balustrade supplies, backed by great customer service and an experienced team. If you have any questions, don't hesitate to get in touch.

What Steel Are Fasteners Made From?

In different industries and manufacturing traditions around the world, specific fasteners have been developed to meet specific needs. Successful fasteners must be cost-effective and perform reliably. To achieve this, fasteners are made from particular steels or steel alloys, optimised for different applications.

Here's a quick overview of the main steel types used to make nuts and bolts. For a deeper look at how these compare, see our steel types comparison guide.

Carbon Steel — Carbon content is varied to achieve different strength grades. Mild steel contains less carbon and has relatively low tensile strength. High tensile steel contains more carbon, giving it significantly higher tensile strength.

Alloy Steel — Chemical elements such as chromium, nickel, or molybdenum are added to carbon steel to create specific properties, such as improved corrosion resistance or strength.

Stainless Steel — Stainless steel is an alloy containing at least 10.5% chromium, which gives it its corrosion resistance. This makes it particularly useful in coastal and marine environments like much of the Sunshine Coast.

Titanium — Titanium alloy fasteners are lightweight, strong, and hard. They tend to be used in specialised applications where weight savings are critical.

What's the Best Type of Stainless Steel?

The answer depends on your application. SS316, for example, offers greater corrosion resistance than SS304 — but it also costs more. If your project doesn't demand that level of corrosion protection, you may be paying for performance you don't need.

Stainless steel fasteners are engineered to meet specific requirements, with trade-offs across strength, corrosion resistance, and cost. For a comprehensive overview, see our deep dive into stainless steel fasteners. Below we compare two of the most popular grades on the Sunshine Coast: SS316 and SS304.

Stainless Steel 316

On the Sunshine Coast — from Caloundra in the south to Coolum Beach, Sunrise Beach, and Peregian Beach in the north — proximity to the ocean often makes corrosion resistance an essential requirement. SS316 is well suited to these conditions.

SS316 achieves its high level of corrosion resistance through a combination of chromium, nickel, and molybdenum. This makes it suitable not just for coastal and marine environments, but also for applications exposed to acidic or alkaline solutions, saltwater, and chloride-containing environments. We stock a range of SS316 wire rope and fittings commonly used in wire rope balustrade installations across the region.

The inclusion of molybdenum is the key differentiator between SS316 and SS304. SS304 contains nickel and chromium but not molybdenum, which limits its performance in highly aggressive environments. For guidance on working with stainless steel, see our article on drilling, tapping, and torquing stainless steel.

SS316 products are generally more expensive than SS304.

Interesting fact: SS316 also comes in an 'L' variant — SS316L — where 'L' stands for low carbon. The reduced carbon content improves weldability.

Summary: For projects on or near the coast, or in a marine environment — particularly in areas like Twin Waters, Mudjimba, Maroochydore, or Golden Beach — SS316 is the recommended choice for a long-lasting stainless steel fastener solution. For more, see our guide on using steel in a marine environment and how to stop outdoor fasteners corroding.

Stainless Steel 304

SS304 is one of the most widely used grades of stainless steel. Like SS316, its alloy includes nickel and chromium — but without molybdenum, its corrosion resistance in highly aggressive environments (such as direct marine exposure) is lower.

That said, SS304 does offer meaningful corrosion resistance for many everyday applications, along with high heat resistance, excellent formability, and ease of cleaning. It's a versatile material used across a wide range of industries, and generally comes in at a lower price point than SS316 — making it a popular choice for many mainstream projects.

Summary: For projects in areas like Eumundi, Maleny, Montville, Landsborough, or Beerwah — further from direct salt air — SS304 may be perfectly suitable and more cost-effective. Where corrosion requirements are moderate, SS304 and SS316 are sometimes used interchangeably, but selecting the right steel for your specific conditions will always optimise both cost and outcome. See our guide on stainless steel vs galvanised steel for help deciding.

Other Grades of Stainless Steel

Stainless steel comes in many other grades beyond SS304 and SS316, including SS430, SS201, and SS410. Each has different compositions, mechanical properties, and applications. We generally stock SS304 and SS316 as they cover the widest range of applications, but if you need something else, contact our team and we'll help you find the right solution.

You can also browse our full range of stainless hardware online.

Mild Steel

Mild steel — also referred to as low carbon steel — contains a relatively low amount of carbon, typically less than 0.3% by weight. It is less hard and strong than high carbon or alloy steels, but it is well-suited to a broad range of engineering applications. It's popular for its low cost and flexibility across many industries, including construction, furniture manufacture, household appliances, and general machinery.

Advantages of mild steel fasteners include:

• Adequate strength for many common applications
• High ductility — it can be stretched or bent without breaking
• Good machinability and weldability
• Wide availability and affordability
• Corrosion resistance when protected with a coating such as zinc, epoxy, or paint

To understand where mild steel sits relative to other types, see our steel types comparison and our guide on understanding bolt grades.

High Tensile Steel

Tensile strength refers to how much stress a material can sustain before breaking. High tensile fasteners are used in applications where durability is critical — where components must be firmly and safely held together under significant tension, vibration, or load.

High tensile steel typically contains a higher carbon content (usually between 0.5% and 0.8% by weight), along with alloying elements such as chromium, vanadium, or molybdenum. These combinations produce a significantly stronger bolt than mild steel equivalents. For more on this topic, see our article what are high tensile fasteners?

What's the Strongest Bolt Grade?

The strongest commonly available bolt grade is Grade 12.9. This is a metric bolt specification that defines minimum tensile strength, yield strength, and elongation. Grade 12.9 bolts are made from alloy steel that has been quenched and tempered — a heat treatment process that produces a high-strength, high-hardness bolt capable of withstanding extreme stress and strain.

For more detail, see our articles on what is 12.9 grade steel, how 12.9 grade steel is made, and 12.9 grade steel vs stainless steel. You might also want to consider: are Grade 12.9 bolts overkill for your project?

Galvanised Steel

Galvanised steel fasteners are produced by dipping regular steel into molten zinc, which forms a protective coating over the surface. This zinc layer protects the underlying steel from moisture and oxygen, providing meaningful corrosion resistance.

Galvanised mild steel fasteners are generally less expensive than stainless steel alternatives. The finish is dull and matte rather than bright and clean — a practical trade-off for many structural and outdoor applications. Galvanised steel is commonly used in outdoor structures, construction, and environments where corrosion resistance is needed but the cost of stainless steel isn't justified.

For tips on keeping your outdoor fasteners in good shape regardless of material, see how to stop your outdoor fasteners corroding and our broader guide to avoiding common problems with bolts.

Drop in and for a Visit!

Whether you're in Maroochydore, Caloundra, Woombye, Yandina, or anywhere across the Sunshine Coast hinterland, Bolt-In Co has the fasteners and expertise to help you choose the right material for the job. Browse our full range or get in touch with our team today.