Stainless Steel vs Cast Iron: A Detailed Comparison

 Introduction

Knowledge of various types of metal is essential whether you are in the construction, automotive, or transport sector. Each has its benefits and drawbacks, making it difficult to determine which is best suited for your needs.

But don’t worry; we’ve got your back. We have done the footwork to prepare this article for you so you can make an informed decision.

What is Cast Iron material?

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Cast iron is molten iron poured into a cast and then given time to solidify. It mainly comprises iron and carbon between 1.2% and 4%. Other elements added during the melting process before being cast into molds may include manganese, sulfur, silicon, and phosphorous.

What is Stainless Steel material?

In simpler terms stainless steel is iron made of carbon and chromium, not less than 10.5%. Molybdenum, nickel, and titanium are added to cast iron to increase its toughness and longevity.

Stainless Steel Vs. Cast Iron: Difference in material

Iron and carbon are the two main constituents of stainless steel. Other materials like chromium and nickel can be added to alter the characteristics and properties. Cast iron constitutes carbon, silicon, and manganese. 

Stainless Steel Vs. Cast Iron: Difference in durability

Regarding durability, both metals have good sides. However, stainless steel has superior durability and resistance to wear. Cast iron can last very long if you take good care of it. Through routine seasoning, you can preserve its natural nonstick surface.

Stainless Steel Vs. Cast Iron: Difference in ease of care

Cleaning and maintaining stainless steel is hassle-free thanks to its corrosion, rust, and staining resistance properties. However, you should note that the material can be prone to scratching, and hard cleaning products should not be used.

You will need special attention with cast iron as it cannot be soaked and can only be cleaned using mild soap and a non-abrasive scrubber. With proper care, you can extend the lifespan of cast iron and maintain its nonstick properties.

Stainless Steel Vs. Cast Iron: Difference in price

As a rule of thumb, the cost of materials, manufacturing techniques, energy, and labor used in producing a product determines its final cost.  And cast iron and stainless steel are no exception. 

On average, one tonne of stainless steel would cost something in the neighborhood of $2,000. A tonne of cast iron would cost around $ 1300 – 1600. 

Stainless Steel Vs. Cast Iron: Difference in corrosion resistance

Cast iron has a higher resistance to corrosion due to its high carbon concentration. The fact that these highly corrosive materials don’t mean they are indestructible. If not properly taken care of, corrosion can occur over time. 

Stainless Steel Vs. Cast Iron: Difference in application

These two materials are reliable and, without a doubt, have become an integral part of numerous industries and everyday applications. As you are going to see, some of their applications overlap, and this is because they share some properties.

Applications Of Stainless Steel

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1. Automotive – Steel is utilized in the automotive industry to build vehicle structures for transporting chemicals, liquids, and food products. Also, steel can be used to manufacture road tankers, shipping containers, and vehicle frames, among other things.

2. Medical sector – Stainless steel is easy to clean and does not easily corrode, so it is favored in the health sector. 

Surgical instruments like scalpels & forceps and implants such as artificial hips are also made of stainless steel.

Other medical equipments manufactured using stainless steel include kidney dishes, operating tables, steam sterilizers, and MRI scanners.

3. Aerospace – Aircraft structures such as fuselage and landing gears are manufactured with stainless steel. Due to high heat resistance, gas turbines can also be manufactured using the material.

4. Energy – Nuclear power plants, power generation, and the oil and gas industry all utilize stainless steel in one way or the other. For instance, pipes,  heat exchangers, tanks, and gaskets, are all stainless steel.

5. Security – High strength, resistance to impact, and durability make stainless steel ideal for security applications. Armoured vehicles, securing fencing, safe room,s, and safe vaults are some of the uses of stainless steel in the security sector.

6. Marine – Underwater electronics, offshore structure marine vessels, and electrical enclosures are just a few things manufactured using stainless steel. 

7. Food industry – Steel also plays a crucial role in the food industry primarily because of its ductility and reactive nature with acidic substances. Kitchen utensils and cutlery are mostly made of stainless steel..

Applications Of Cast Iron

For you to better understand the uses of cast iron, we’re going to discuss the uses as per the type.

Grey cast iron – Gray cast iron performs very well under low lubricant and thus is used in making engine blocks and cylinder heads. 

White cast iron – It’s brittle nature and abrasion resistance makes it ideal for manufacturing mill linings, railroad brakes, crushers, slurry, and pump housings. 

Ductile cast iron is easily machinable and has a high yield strength with good fatigue, making it perfect for making heavy-duty gears, crankshafts, and hydraulic and suspension components. 

Malleable cast iron – Malleable cast iron is used to manufacture heavy-duty-bearing surfaces, farm and construction machinery

Cast Iron Vs. Stainless steel: Difference in strength

Note that strength is determined by heat treatment, composition, and manufacturing techniques employed. 

1. Tensile strength is the maximum stress a given material can withstand when pulled apart before breaking. Stainless steel has higher tensile strength than cast iron. It ranges from 500mpa  to over 2,000mpa whereas that for cast iron is 150-200mpa2.

2. Yield strength – The maximum possible stress a ductile material can undergo before the permanent change occurs is called yield strength. 

Stainless steel has higher yield strength than cast iron, because of carbon and nitrogen elements. The steel yield strength may increase to 1000mpa, while cast iron can range between 100-200mpa.

3. Compression strength – Compression strength is the maximum compression stress a material can withstand before fracture. 

Cast iron has excellent compression strength thanks to the graphite flakes that help resist deformation under compression forces. Stainless steel also experiences good compression but does not match that of Cast iron.

Advantages Of Stainless Steel

  1. Some stainless steel grades can resist high temperatures with other cryogenic temperatures.
  2. Stainless steel can easily be cut, welded, and machined
  3. It’s available in my finishes which boosts its aesthetic appeal.
  4. It is easy to clean and maintain, making it the first choice in the healthcare and food industry.
  5. Resistant to corrosion
  6. High heat resistance makes it suitable for application surrounding thermal stress.
  7. Stainless steel is 100% recyclable.
  8. Highly durable, which reduces the need for frequent maintenance and repair.

Disadvantages of Stainless Steel 

  1. Quite expensive 
  2. It is relatively heavy compared to other alternatives, and this can increase installation and transportation costs.
  3. Some stainless steel grades are prone to scratches.
  4. High thermal conductivity can be a limiting factor where heat insulation is needed.
  5. Although they are generally easy to clean, they require regular maintenance to keep their appearance intact.

Advantages Of Cast Iron 

  1. High heat retention capabilities
  2. Its natural nonstick surface makes it easier to clean
  3. cast iron is highly castable
  4. easily machinable
  5. Cheaper compared to stainless steel
  6. Cast iron has good damping properties
  7. Excellent wear resistant
  8. Highly durable

Disadvantages Of Cast Iron

  1. It corrodes and rusts easily compared to stainless steel.
  2. Cookware might require regular seasoning 
  3. It is highly brittle.
  4. Low tensile stress
  5. Cast iron is also relatively heavy.

Types Of Stainless Steel

  1. Austenitic – It’s the most used grade and contains austenite with a high percentage of nickel. Additionally, it is strong and malleable, making it easily machinable.
  2. Duplex – Contains a max of 30% chromium and features a low carbon concentration of less than 0.1%. It is also resistant to cracking, high temperature, and oxidation, giving it endless application in various areas.
  3. Ferritic – Ferritic is a mixture of duplex and austenitic. It is perfect for marine applications because it does not easily corrode under harsh environments and saltwater in the sea.
  4. Martensitic – The metallurgical structure of martensitic comprises two phases, ferrite, and austenite. It has twice the strength of austenite. It’s also hard, brittle, and not the easiest stainless steel to weld.  

Types Of Cast Iron 

This material takes on many forms, each with its own set of unique properties and potential applications. These include;

Grey cast iron – It contains graphite microstructure which gives it a grey color when fractured. Although not malleable, it has exceptional thermal conductivity, making it highly efficient in dissipating heat. 

One of the unique features of grey cast iron is its remarkable damping capacity due to the presence of graphite. This property allows it to absorb energy and convert it into heat efficiently.

White cast iron – White cast iron, also known for its appearance due to the fracture, is hard, brittle, and difficult to machine.

Ductile cast iron – It has similar mechanical properties to steel. As it solidifies, spherical graphite nodules form, giving it more strength and stronger shock resistance than grey cast iron.

Malleable cast iron is produced by annealing white cast iron, which turns it from brittle to malleable cast iron. It has more carbon and silicone, which gives it more flexibility and strength.

Composition of Stainless Steel

stainless steel sheet

 

Stainless steel alloy primarily comprises Chromium, Iron, and other elements. However, this may vary depending on the grade. Below are some of the common elements that stainless steel is composed of: 

1. Chromium 

Chromium is a major element in varying types of stainless steel, available in varying quantities in the range of 10-30%.  

2. Iron

Iron makes up a greater composition of stainless steel as its base metal. Furthermore, it is responsible for this alloy’s strength and structural integrity. 

3. Nickel

Makes up 8-12% of the total composition of stainless steel is nickel. Nickel enhances the corrosion properties of the alloy, especially in environments that tend to be aggressive. It’s also a significant contribution to the overall strength and toughness of the alloy. 

4. Carbon

Stainless steel is also comprised of carbon. Typically, carbon will comprise less than 0.08% in most stainless steel grades. Carbon is available in lower amounts to maintain the stainless properties of stainless steel. 

5. Molybdenum 

In specific grades of stainless steel, molybdenum might be available in ranges of 2-6% of the total composition. Molybdenum will enhance the corrosion properties of stainless steel, especially in environments rich in chloride. 

6.Other Elements In Stainless Steel

Besides the five elements we have discussed, stainless steel might also comprise other elements in smaller proportions. Most of these elements are added to stainless steel to help it achieve specific properties to better perform its functions. They may include Niobium, Nitrogen, Copper, and Titanium. 

Composition Of Cast Iron

Cast iron alloy comprises Iron and Carbon as its basic elements and other additional elements and impurities in different amounts to enhance its functionality. Cast iron comprises of: 

1. Iron 

The main component of cast iron is iron. It makes up 90% of the total composition of the alloy. Iron provides cast iron with strength and structural integrity properties making it a go-to alloy for various applications. 

2. Carbon

Carbon is another crucial element in cast iron that makes up 2-4% of the total composition of it. High carbon content gives cast iron characteristics such as easy cast ability, high resistance to wear, and excellent ability to retain heat. 

3. Silicon 

Silicon is available in the range of 1-3%. It is essential in cast iron as it promotes the formation of graphite, improves the alloy’s strength and hardness, and enhances the element’s fluidity during casting. 

4. Manganese

Manganese often exists in cast iron in minimal amounts, usually less than 1%. The element helps refine the alloy’s grain structure, improving its hardness, strength, and overall quality. 

5. Sulfur And Phosphorous 

Most manufacturers consider sulfur an impurity to cast iron as it can weaken the strength of the alloy. However, in small quantities combines with iron to form iron sulfide. This prevents the formation of graphite in the alloy. 

Phosphorous is only available in small traces because it makes the iron brittle hence easy to break. However, adding small amounts of phosphorous to cast iron improves its wear resistance. Small amounts of phosphorous are also beneficial to the strength of the alloy. 

6. Traces Of Other Elements

Other elements in small traces might exist in different types of cast iron. Small traces of elements that may compose of cast iron include nickel, copper, chromium, and molybdenum. Most of these elements existing in small traces are added to modify specific properties of the alloy. 

The exact composition of cast iron alloy can vary depending: on desired properties, specific casting methods and its intended applications. 

Environmental Impacts Of Cast Iron And Stainless Steel

Production and use of cast iron and stainless steel tend to impact the environment in different ways. Below are some of the effects the two alloys have on the environment: 

1. Energy Consumption 

The production of stainless steel involves many steps, like smelting, refining, and shaping. A significant is needed due to the high temperatures required for melting and forming the alloy. 

Similarly, the production process of silicone requires a substantial amount of energy. However, cast iron generally requires less energy compared to stainless steel due to a simpler manufacturing process. 

2. Toxic Emissions

Stainless steel production is known for its relatively low toxic emissions. Using modern technologies and proper air and water pollution control measures in steel plants helps minimize the release of harmful substances into the environment. 

In contrast, cast iron production can generate considerable toxic emissions, particularly during the melting and molding stages. These emissions may include sulfur dioxide, carbon monoxide, and other pollutants. 

3. Waste Materials

Stainless steel manufacturing typically generates less waste material compared to cast iron. Additionally, the scrap generated during production can be recycled. Cast iron generates more waste materials because of sand molds and metal scraps. 

4.Recycling

alloy recycle

Stainless steel is highly recyclable, and the recycling process can be repeated multiple times without significantly degrading its properties. This makes stainless steel an environmentally friendly material, as it reduces the demand for new raw materials. On the other hand, cast iron is also recyclable, although recycling may involve additional steps compared to stainless steel.

Tuolian Metals: Your one-stop supplier for stainless steel

Tuolian Metals is your go-to place for all your stainless steel needs. As a leading manufacturer and supplier, they offer a wide range of high-quality stainless steel products tailored to your requirements. 

You are covered whether you need stainless steel sheets, coils, tubes, strips,s or custom-made components. The state-of-the-art manufacturing techniques, meticulous quality control, and competitive pricing make Tuolian stand out. 

FAQs

Does stainless steel last longer than cast iron?

Stainless steel outperforms cast iron in longevity and resistance to corrosion because of the protective chromium layer on the surface, which prevents rust and corrosion. 

Does stainless steel rust over time?

Although stainless steel is resistant to rust and corrosion, this does not mean it is indestructible to both. The protective layer can be damaged by exposure to specific chemicals, moisture, and environmental variables, allowing rust to form. However, routine cleaning and maintenance can help avoid rust. 

One Stop Stainless Steel Supply.

Whether you need stainless steel materials for your business or fabrication projects, TuoLian is your best supplier. You can find all types, grades, and thicknesses based on your needs. Guaranteed that we provide the best quality at a reasonable cost.
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