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Both galvanized and stainless steel are very strong materials but each one is used in different places. The main advantage of galvanized steel is that it does not corrode easily and cost less. On the other side, stainless steel is preferred for its appealing finish and strength. This blog text gives a clear comparison of their main factors for easy material selection choices.
What is Galvanized Steel?
This steel is made from hot dip galvanizing or electroplating processes which turn carbon steel into galvanized steel by applying a zinc coating. The zinc layer is 20 to 100 microns thick and acts as a sacrificial barrier to corrosion. The metallurgical bond guarantees the material is tough in harsh environments.
What is Stainless Steel?
Stainless steel is an iron based alloy with chromium and other elements. Its distinct property is the self healing passive oxide layer formed by chromium which provides inherent corrosion resistance. This engineered metal keeps structural integrity across a broad temperature range from -200°C to 800°C.
Top 8 Differences of Galvanized Steel vs. Stainless Steel
Picking between galvanized steel and stainless steel requires that you fully grasp their main features. Each material has its advantages depending on the application. Let’s get into the 8 key differences between these two.
1. Composition
Galvanized steel is composed of a carbon steel base, coated with zinc through hot dip galvanization. This process creates different layers like Gamma (75% zinc, 25% iron), Delta (90% zinc, 10% iron), Zeta (94% zinc, 6% iron) and a pure zinc Eta layer.
Stainless steel, on the other side, is an iron based alloy. It has a minimum of 10.5% chromium and varying amounts of nickel (0-22%) and molybdenum (0-8%).
2. Corrosion Resistance
In terms of corrosion resistance, stainless steel performs better than galvanized steel because of the self healing chromium oxide layer. The zinc coating of galvanized steel serves as a sacrificial anode thus protecting the base metal for 15 to 20 years in normal conditions. However, it becomes weaker in highly acidic or alkaline conditions.
Whereas stainless steel provides constant corrosion protection in tough environments. The material can also withstand temperatures of up to 800 °C and remains structurally sound in highly corrosive chemical conditions.
3. Strength
Stainless steel is better than galvanized steel in terms of both tensile and yield strength. Stainless steel possesses a tensile strength of between 50000 and 300000 psi and a yield strength of approximately 210-500 MPa due to its austenitic microstructure. Alternatively, galvanized steel’s tensile strength is 50,000 to 80,000 psi and its yield strength is 250-350 MPa which only indicates that it is more flexible and less powerful.
4. Cost
Compared to stainless steel, galvanized steel is cheaper. Galvanized steel is a more cost effective investment at the beginning with hot dip galvanization just adding minimum processing cost to base steel.
On the other hand, stainless steel costs you a lot more at start due to its complex alloying elements like nickel, chromium and molybdenum. However, it is the durability of stainless steel that usually gives a higher benefit in the long run as there are no frequent maintenance costs.
5. Maintenance and Durability
Stainless steel beats galvanized steel in maintenance and longevity. A simple water and detergent wash is enough for stainless steel and it last over 50 years. But galvanized steel needs regular inspections and special care to maintain its zinc coating, particularly in environments where pH is below 6 or above 8.
6. Aesthetic Appearance
The appearance of these two materials is vastly different. Stainless steel has a polished, mirror like finish with surface roughness of 0.1 to 0.5 micrometers. Different finishing techniques like brushing, blasting or electropolishing can be done to customize its appearance. Whereas galvanized steel has a spangle pattern and matte gray color look. Over time, its zinc coating develops a natural patina through oxidation.
7. Magnetic Properties
Magnetic properties also differ between these two materials. Galvanized steel retains strong ferromagnetic properties with magnetic permeability of 100 to 600 μr while stainless steel magnetic properties vary depending on the grade. Austenitic (300 series) stainless steel is non-magnetic due to its nickel content and ferritic (400 series) grades are magnetic like regular steel.
8. Environmental Impact
Among the energy intensive industrial processes, the use of electric arc furnaces for stainless steel manufacturing has been found to be a biggest source of energy related emissions, producing 3.3 kg of CO2 per ton. Nevertheless, it is highly recyclable and also has a longer lifespan.
Galvanized steel generates lower carbon dioxide emissions. But it needs zinc removal before recycling.
Galvanized Steel vs Stainless Steel Applications
Galvanized steel and stainless steel have their place in different industries. Each steel has its advantages for particular uses.
Galvanized Steel Applications
- Construction and Infrastructure: In construction, galvanized steel is used to make products like columns, beams and trusses. Its strong zinc coat protects the steel from weathering in guardrails, bridges and the frameworks of buildings.
- Automotive Industry: Galvanized steel is necessary in vehicle manufacturing. It forms body panels, chassis frames and structural elements. For parts exposed to harsh conditions like moisture and road salt, manufacturers use G60-G90 coating grades. These grades provide superior corrosion protection in underbody parts and wheel wells.
- Agriculture: Modern day agriculture depends largely on galvanized steel. Farmers use it for grain silos, livestock fencing, irrigation pipes and greenhouse frameworks. The zinc coating is resistant to fertilizers, soil chemicals and harsh weather conditions found in farming operations.
- Utilities and Telecommunications: In telecommunications infrastructure, the transmission towers, antenna mounts and cable support systems are made from galvanized steel. The zinc coating assures longevity in outdoor installations while the metal beneath provides structural support to equipment during harsh weather. Underground conduit systems and utility pole hardware are also made from galvanized steel.
- Household Appliances: Many household appliances use galvanized steel. Washing machine tubs, dishwasher frames, and dryer drums, air conditioner housings, microwave cavities, refrigerator panels and water heater tanks are usually made from this material.
Stainless Steel Applications
- Food and Beverage: Stainless steel in the food industry is used for the manufacturing of storage silos, brewing vats, mixing systems, milk pasteurization units, conveying systems, refrigeration units, commercial ovens and preparation surfaces. These parts are intended to provide proper and safe handling and storage of foods during processing.
- Medical and Pharmaceutical: Stainless steel is the distinct component used to make MRI machines, surgery tools and lab equipment. It has antimicrobial properties, which makes it the right material for pharmaceutical mixing tanks and clean room parts.
- Architecture and Construction: Architects apply stainless steel for making elevator cladding, facades and curtain walls. It is highly durable and therefore suitable for roofing systems, handrails and security bollards. Most tall buildings use stainless steel materials in their support structures, wall sheathing and bridge cables.
- Automotive and Aerospace: Stainless steel is a commonly used material for the construction of fuel tanks, exhaust systems, engine components, turbine blades, aircraft fuselages, rocket propulsion chambers and aircraft landing gear mechanisms. These parts need to be heat resistant and strong for operating in such severe physical conditions.
- Energy and Power Generation: It is primarily applied in boiler tubes, turbine components and heat exchangers. This steel demonstrates outstanding high temperature strength, thus, it is the appropriate one for geothermal systems and nuclear reactors and even in the case of projects like wind turbine structures and solar panel frames for better corrosion resistance.
Galvanized Steel vs. Stainless Steel- Which One to Pick?
Your project needs will decide if galvanized or stainless steel is the better option. Galvanized steel is good for freshwater environments, construction projects and scenarios where maintenance is possible. Its zinc coating provides adequate protection at 20% of the cost of stainless steel.
For marine environments, medical applications, food processing or situations where ultimate corrosion resistance is required, stainless steel is an appropriate choice. Although it is more expensive upfront, its self healing chromium oxide layer and low maintenance normally mean lower lifetime costs.
Environmental exposure, budget and maintenance capability are other important factors to consider. Chlorinated water applications prefer galvanized steel while saltwater environments require stainless steel for protection.
Conclusion
In short both stainless and galvanized steel have different uses in industrial sector. The former provides cost effective corrosion protection for general use while stainless steel is used for durability in intense environment. You should take the necessary steps based on your long term costs and project needs.
If you need any CNC machining or fabrication services related to galvanized and stainless steel then Richconn is the best provider. Plz feel free to contact us at any time and share your particular needs.
FAQs
Is welding stainless steel more challenging than welding galvanized steel?
Yes. welding of stainless steel is more difficult than the welding of galvanized steel. Heat control must be exact as well as filler metals that are usually used to prevent chromium carbide precipitation. Galvanized steel welding only has a requirement of decontamination of workplace, so it is easier.
Can galvanized steel be painted?
Yes, but it can only be done through proper planning. First you must scrub the surface to make it dirt free. Next, use the vinegar as primer and at the final stage, apply galvanized steel specific paint or acrylic latex. Stay away from alkyd and oil based paints.
Which material is more ductile: galvanized steel or stainless steel?
Stainless steel is more ductile than galvanized steel due to its austenitic structure that allows larger strain to develop without failure. Stainless steel can be extended to 40% strain while galvanized steel can be stretched only 10-20%.
How do galvanized steel vs stainless steel fare in acidic environment?
Stainless steel is far better than galvanized steel in acidic surroundings. The chromium oxide layer in stainless steel provides better protection against acid attack. On the other hand, galvanized coatings deteriorate quickly in acidic conditions.
How much does stainless steel weigh compared to galvanized steel?
Stainless steel is somewhat lighter than galvanized steel. The density of stainless steel is 7.7-8.0 g/cm³ due to alloying elements whereas that of galvanized steel is 7.6-7.8 g/cm³.
