The Most Common Material Question
Every week we receive dozens of inquiries that boil down to the same question: “Should I use stainless steel or galvanized steel for my parts?” The answer is never one-size-fits-all. It depends on your operating environment, budget constraints, aesthetic requirements, and long-term maintenance expectations.
This guide provides a thorough comparison to help you make an informed decision. We cover the technical properties, cost implications, fabrication differences, and real examples from our production floor.
What Is Galvanized Steel?
Galvanized steel is carbon steel (typically SPCC, SPHC, or SS400 base) coated with a layer of zinc to prevent rust. The zinc acts as a sacrificial barrier — it corrodes before the base steel does, extending the part’s life.
Types of Galvanized Steel
| Type | Code | Zinc Method | Coating | Surface | Best For |
|---|---|---|---|---|---|
| Hot-dip galvanized | SGCC | Dipped in molten zinc | 20-60 microns | Spangle pattern | Structural, ducting |
| Electro-galvanized | SECC | Electroplating | 5-15 microns | Smooth, uniform | Enclosures, panels |
| Pre-painted galvanized | PPGI | Hot-dip + paint | Zinc + paint | Color-coated | Roofing, cladding |
SGCC is the most common sheet in Vietnam, available in thicknesses from 0.4mm to 3.2mm. It is the default choice for indoor fabrication where cost matters most.
What Is Stainless Steel?
Stainless steel is an alloy of iron, chromium (minimum 10.5%), and often nickel, molybdenum, or other elements. The chromium forms a self-healing oxide layer on the surface that resists corrosion without any coating.
Common Stainless Grades in Sheet Metal
| Grade | Composition | Magnetic? | Corrosion Resistance | Price Level |
|---|---|---|---|---|
| SUS201 | Cr-Mn-Ni (low Ni) | Slightly | Moderate | Lowest |
| SUS304 | 18Cr-8Ni | No | Excellent | Medium |
| SUS316 | 16Cr-10Ni-2Mo | No | Superior | High |
| SUS430 | 17Cr (no Ni) | Yes | Good | Low |
SUS304 is the workhorse grade for 90% of stainless sheet metal applications. SUS316 is reserved for marine, chemical, or medical environments where chloride resistance is critical.
Head-to-Head Comparison
Core Properties
| Property | Galvanized Steel (SGCC) | Stainless Steel (SUS304) |
|---|---|---|
| Tensile strength | 270-500 MPa | 515-620 MPa |
| Yield strength | 205-350 MPa | 205-310 MPa |
| Density | 7.85 g/cm3 | 8.00 g/cm3 |
| Melting point | ~1,500°C | ~1,400-1,450°C |
| Thermal conductivity | 50 W/mK | 16 W/mK |
| Hardness (Rockwell B) | 50-75 | 70-90 |
Corrosion Resistance
This is the defining difference between the two materials.
| Environment | Galvanized | Stainless 304 | Stainless 316 |
|---|---|---|---|
| Indoor dry | 20+ years | Lifetime | Lifetime |
| Indoor humid | 10-15 years | Lifetime | Lifetime |
| Outdoor covered | 5-10 years | Lifetime | Lifetime |
| Outdoor exposed | 3-7 years | 20+ years | Lifetime |
| Coastal/salt spray | 1-3 years | 10-15 years | 20+ years |
| Chemical exposure | Poor | Good | Excellent |
| Food contact | Not suitable | FDA approved | FDA approved |
Key insight: Galvanized steel is perfectly adequate for indoor applications. It only falls short when exposed to sustained moisture, salt, or chemicals.
Cost Comparison
| Cost Factor | Galvanized (SGCC) | Stainless (SUS304) | Ratio |
|---|---|---|---|
| Raw material (1.5mm sheet) | ~28,000 VND/kg | ~85,000 VND/kg | 1 : 3.0 |
| Laser cutting cost | Base rate | +30-50% (nitrogen gas) | 1 : 1.4 |
| Bending cost | Base rate | +10-20% (springback) | 1 : 1.15 |
| Welding cost | Base rate | +20-40% (TIG required) | 1 : 1.3 |
| Surface treatment | Powder coat required | Optional (natural finish) | Varies |
| Total fabricated cost | Base | 2.5-4x | Depends on finish |
Important nuance: While stainless raw material costs 3x more, the total fabricated part cost difference is often only 2.5-3x because stainless does not require powder coating for most applications. If your galvanized part needs premium powder coating, the gap narrows further.
Fabrication Differences
| Process | Galvanized | Stainless 304 |
|---|---|---|
| Laser cutting gas | Compressed air or oxygen | Nitrogen (bright edge) |
| Cutting speed (2mm) | ~25 m/min | ~18 m/min |
| Minimum bend radius | 1x thickness | 1x thickness |
| Springback | Low (2-3°) | Higher (4-6°) |
| Welding method | MIG (fast) | TIG (cleaner, slower) |
| Post-weld treatment | Repaint weld area | Passivation or pickle |
| Threading/tapping | Easy | Harder (work hardens) |
Weight and Thickness
For equivalent structural rigidity, stainless steel can sometimes be specified thinner due to its higher tensile strength. However, the density difference is minimal (7.85 vs 8.00 g/cm3), so weight savings are negligible unless you redesign the part for the material.
When to Choose Galvanized Steel
Galvanized steel is the right choice when:
- The part is used indoors with no moisture or chemical exposure
- Budget is the primary constraint and you need maximum parts per dollar
- The part will be powder coated anyway (the zinc layer is hidden under paint)
- Magnetic properties are needed (e.g., parts used with magnetic tools or sensors)
- High-volume production where material cost dominates total cost
Real Examples from Our Shop
- Electrical enclosures (IP54) — SGCC 1.5mm, powder coated RAL 7035
- Server rack panels — SECC 1.2mm, powder coated black
- HVAC ductwork — SGCC 0.8-1.2mm, left unpainted
- Machine guards — SGCC 2.0mm, powder coated safety yellow
- Retail display fixtures — SECC 1.0mm, powder coated custom color
When to Choose Stainless Steel
Stainless steel is the right choice when:
- The part is used outdoors or in humid/wet environments
- Food or pharmaceutical compliance is required (FDA, GMP)
- Chemical resistance is needed (acids, alkalis, solvents)
- No painting is desired — the natural brushed or polished finish is the final surface
- High temperature operation (above 400°C where zinc would evaporate)
- Hygiene is critical — stainless is easier to clean and does not harbor bacteria
Real Examples from Our Shop
- Kitchen equipment panels — SUS304 1.5mm, brushed No.4 finish
- Outdoor signage brackets — SUS304 2.0mm, polished
- Pharmaceutical enclosures — SUS316 1.5mm, electropolished
- Water treatment panels — SUS304 2.0mm, passivated
- Food processing guards — SUS304 1.2mm, 2B finish (easy to clean)
The Middle Ground: Galvanized with Premium Coating
For applications that need better corrosion resistance than bare galvanized but cannot justify stainless steel prices, consider galvanized steel with a multi-layer coating system:
- Zinc phosphate pretreatment — Chemical conversion layer for adhesion
- Epoxy primer — 40-60 microns, anti-corrosion base
- Polyester powder coat — 60-80 microns, UV-resistant topcoat
This system can survive 10-15 years outdoors at a fraction of the cost of stainless steel. It is commonly used for outdoor electrical cabinets, telecom enclosures, and industrial equipment housings.
SUS201 — The Budget Stainless Option
SUS201 has gained popularity in Vietnam as a cheaper alternative to SUS304. It replaces some nickel with manganese, reducing cost by about 30%. However, there are important trade-offs:
| Property | SUS201 | SUS304 |
|---|---|---|
| Nickel content | 1-5.5% | 8-10.5% |
| Corrosion resistance | Moderate | Excellent |
| Rust risk in humid air | Yes (pitting) | Minimal |
| Work hardening | Higher | Moderate |
| Weldability | Fair | Excellent |
| Price vs 304 | 25-35% less | Baseline |
Our recommendation: Use SUS201 only for indoor decorative applications where minor surface staining is acceptable. For anything functional or outdoor, invest in SUS304. The cost savings of SUS201 are not worth the corrosion risk in Vietnam’s tropical climate.
Material Selection Decision Flowchart
Ask yourself these questions in order:
- Will the part contact food, water, or chemicals? Yes -> Stainless 304 or 316
- Will the part be installed outdoors? Yes -> Stainless 304 (or galvanized with premium coating for budget)
- Will the part be in a humid environment (>70% RH)? Yes -> Stainless 304 recommended
- Does the part need a bare metal finish (no paint)? Yes -> Stainless 304 (brushed/polished)
- Is the part purely indoor and will be painted? Yes -> Galvanized SGCC (most cost-effective)
- Is it a prototype or short-run? Either works — choose based on end-use environment
View Our Full Material Catalog
We stock all common sheet metal materials from 0.5mm to 25mm thickness. Visit our materials page for the complete list of available grades, thicknesses, and standard sheet sizes.
Get Expert Material Advice
Not sure which material is right for your application? Our engineers can review your design and recommend the optimal material based on your operating conditions and budget.
Contact us with your drawings or a description of your application, and we will provide a material recommendation along with a detailed fabrication quote — free of charge.