What Steel to Use Where for Your Fabrication Project

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Galvanised vs Stainless steel: what steel to use where for your fabrication project?

Packaging12 Jan 2025

Galvanised vs Stainless steel: what steel to use where for your fabrication project?

Choosing between galvanised and stainless steel for a fabrication project depends on
various factors, including the intended use, environmental conditions, and budget considerations. Stainless steel is preferred over galvanised steel in various applications due to its lower reactivity, smoother surface texture, and suitability for medical use. Its resistance to corrosion and ease of cleaning make it ideal for medical equipment, tools, and implants where long-lasting performance is crucial. Here's a comparison between galvanised and stainless steel to help you make an informed decision:

Galvanised steel:

Protection: galvanised steel is coated with a zinc layer, providing excellent corrosion resistance. This makes it suitable for outdoor and marine environments.
Aesthetics: the appearance of galvanised steel is different from stainless steel. It has a shiny, spangled surface due to the zinc coating.
Application: commonly used in outdoor structures, fencing, roofing, and applications where corrosion resistance is needed but not necessarily in direct contact with corrosive substances.

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Stainless steel
Shaping stainless steel: stainless steel, especially certain types called austenitic grades like 310S N1, HR 304 N1, HR 304L N1, etc., can be shaped like drawing, forging, folding, and spinning. These methods give stainless steel its strength and flexibility.

Depending on the type of stainless steel used, it can become stronger through work hardening, which involves shaping it while it's cold. This makes it suitable for uses where strength is important in addition to resistance to rust. Due to high Cr content(~18 to 25% in austenitic stainless steel, it has very high resistance against rust formation and protection against corrosive environments such as marine or industrial conditions. and resistance to rust are important.

Different methods for different stainless steels

Austenitic stainless steel can be shaped easily and is good for welding.
Martensitic stainless steel can be made stronger through heating and cooling.
Ferritic stainless steel can't be heated and cooled like martensitic steel but can still be shaped.
Duplex stainless steel (two-phase alloys containing an equal proportion of ferritic and austenitic phases) has good welding abilities and expands less when heated than other stainless steels.

Shaping techniques

Machining: cutting stainless steel is tricky because it's tough, especially austenitic grades. There are special grades made for easier cutting.
Welding: most stainless steels can be welded, but each type needs different care by using stainless steel electrodes of similar chemical composition.
Soft soldering: this is a method using a solder made of lead and tin, but it's not strong enough for some uses.

Advantages of stainless steel
Corrosion resistance: stainless steel is known for its exceptional corrosion resistance, making it ideal for harsh environments, such as coastal areas or places with exposure to chemicals.
Strength: stainless steel is generally stronger than galvanised steel, providing better structural integrity in certain applications.
Aesthetics: stainless steel has a more polished and modern appearance compared to galvanised steel, making it a preferred choice for architectural and decorative applications.
Application: widely used in applications where hygiene, durability, and corrosion resistance are crucial, such as food processing equipment, medical devices, and architectural structures.

Considerations for your fabrication project
Corrosion resistance:
Galvanised steel: galvanisation involves coating steel with a layer of zinc to protect it from corrosion. However, galvanised steel may corrode over time, especially in harsh environments with exposure to moisture and chemicals.
Stainless steel: stainless steel contains chromium, which forms a passive oxide layer on the surface, providing excellent corrosion resistance. It is ideal for applications where high corrosion resistance is essential, such as marine environments, chemical processing plants, and food processing equipment. Stainless steel is more corrosion-resistant than galvanised steel and is often chosen for long-term durability.

Strength and durability:

Galvanised steel offers good strength and durability, making it suitable for various structural applications. However, the zinc coating may degrade over time, affecting its long-term durability, especially in corrosive environments.

Stainless steel is known for its exceptional strength and durability, making it suitable for demanding applications where structural integrity is crucial. It retains its corrosion resistance and mechanical properties even in harsh conditions, contributing to its long-term performance.

Cost:

Galvanised steel is generally more cost-effective than stainless steel, making it a preferred choice for projects with budget constraints.
Stainless steel is more expensive than galvanised steel due to its higher alloy content and manufacturing processes. However, its longevity and corrosion resistance can justify the higher initial investment, especially for long-term applications.

Aesthetic considerations:
Galvanised steel: galvanised steel has a characteristic shiny, metallic appearance due to the zinc coating. It may develop a matte grey patina over time, depending on environmental conditions.
Stainless steel: stainless steel has a sleek, modern appearance with a polished or brushed finish, making it suitable for architectural and decorative applications where aesthetics are important.

Environmental considerations:

Galvanised steel: galvanisation involves the use of zinc, which is a recyclable material. However, the galvanisation process may involve chemicals and energy, contributing to environmental concerns.
Stainless steel: stainless steel is fully recyclable and has a long lifespan, reducing the need for frequent replacement and minimising environmental impact over time.

Cost-effective steel fabrication solutions for small businesses involve minimising costs while maintaining quality and efficiency. Strategies include optimising material usage by calculating requirements and sourcing locally, streamlining processes through lean manufacturing principles, and investing in modern equipment like CNC machines to reduce labour costs. Outsourcing non-core activities, investing in training, and managing inventory efficiently are also key. Standardising processes, ensuring energy efficiency, implementing quality control measures, and collaborating with suppliers can further reduce costs.