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Steel is a term that actually describes an entire family of metal alloys and is a versatile and common type of metal with a wide range of applications and uses. There are many grades, but most types of steel fall into two broad categories, carbon steel and stainless steel. Although they have the same basic composition of iron and carbon, steel types tend to have multiple alloying elements. Carbon steel tends to have less than 10.5% chromium, but steel must contain at least 10.5% chromium to be considered stainless steel. These differences give each steel its own characteristics. The differences between carbon steel and stainless steel are described below.

Stainless steel

Stainless steel refers to a type of steel defined by the addition of chromium and some other alloying elements such as nickel. It is sometimes called inox steel because it is designed to prevent oxidation and is therefore "non-oxidizable". Iron oxidizes when exposed to oxygen, causing it to rust, but chromium can be exposed to oxygen without going through this process. Therefore, stainless steel is given a protective layer of chromium to form a barrier between ambient oxygen and the iron content of the metal. This makes it resistant to corrosion or rusting and makes it "stainless steel".

Types of stainless steel

Stainless steels with different chromium content will give it different properties, lower chromium content usually results in cheaper but less durable steel. Stainless steel comes in many types, including:

Austenitic, the most widely used type of stainless steel, has low yield strength but strong corrosion and heat resistance, and is often used in household goods, industrial pipes and vessels, buildings and building exteriors - this is the largest family of stainless steels, approximately Two-thirds of stainless steel production

Ferritic, a steel that is usually free of nickel and generally has better corrosion, heat and crack resistance than the more common types, often used in washing machines, boilers and interior construction

Martensite, due to its low chromium content, is magnetic and less resistant to corrosion than other stainless steels - these materials are very hard and strong and are used to make knives and turbine blades

Duplex steels are composites of austenitic and ferritic steels that are both strong and flexible, with twice the yield strength of austenitic stainless steels and are used in the paper, pulp, shipbuilding and petrochemical industries

Precipitation, which has the corrosion resistance of austenitic metals but can be hardened to higher strengths, so can be very strong when other elements such as aluminum, copper and niobium are added

advantage

Corrosion resistance

High and low temperature resistance

There are many types

strong and sturdy

Low maintenance and easy to clean

Long lasting and relatively low cost over its lifetime

If an appealing cosmetic appearance is required, specific finishes are available and are not prone to tarnishing

Eco-friendly and recyclable

shortcoming

High cost, especially the initial fee

Can be a difficult metal to work with, especially without the highest tech machines and techniques

Often results in costly waste and rework

application

Stainless steel has a wide range of uses and industrial applications, depending on the type of steel used. Stainless steel was first used in the automotive industry by Ford in the 1930s and has been used in exhaust systems, grilles, trims and structural components of vehicles ever since. This extends to aircraft manufacturing, for aircraft frames, jet engines and landing gear. Its corrosion resistance, low maintenance and ease of cleaning make it suitable for transport and interaction with chemicals, and is often used in clean and sterile environments. Therefore, medical technology is also a fairly common use.

The strength, resistance and flexibility of certain stainless steels make them a common feature in construction, and their aesthetic features and attractive finishes also help to achieve this. For example, the Eurostar terminal in London and the Helix Bridge in Singapore frequently use stainless steel.

One of the most common everyday uses of stainless steel is in the food and catering industry, where it is used to make cookware, cutlery, kitchen accessories and appliances. Utensils such as knives are made from less tough stainless steel, while tougher stainless steel is used in grills, ovens, pans and sinks.

Carbon steel

Carbon steel, on the other hand, has a much lower chromium content, but is a carbon-iron alloy with only a few other materials (if any) as part of its composition. Therefore, it can be called a "low alloy" steel. Both stainless steel and carbon steel have this basic composition, but carbon steel can be defined by its carbon content. This is usually around 2-2.5%, but this usually varies. While not as prone to rusting as stainless steel, carbon steel is generally less expensive and has different mechanical properties depending on the carbon content.

Mild steel is weaker and softer, but easier to machine and weld; while high carbon steel is stronger, it is more difficult to machine.

Types of carbon steel

The defining element of any carbon steel alloy is its carbon content, so this is how the various carbon steels are ordered and classified.

Mild Steel: The most widely used form of carbon steel, with less than 0.25% carbon - they are usually relatively weak and soft, but are easier to weld and ductile, so are often machined and welded to keep costs down

Medium carbon steels: 0.25-0.6% carbon and 0.6-1.65% manganese, these metals can be improved by heat treatment, although this can only be done in very thin sections unless additional alloying elements are added – these steels have a lower ratio Carbon steel is stronger but less ductile

High carbon steel: This is the hardest, toughest carbon steel, the least ductile, very wear resistant, and is almost always quenched and tempered - they tend to have 0.6-1.25% carbon and 0.3-0.9 manganese %

advantage

increased intensity

cheaper than stainless steel

Wear-resistant

Durable and shock resistant

Safe to handle and use compared to other metals

Eco-friendly and easy to recycle

shortcoming

Strong and sometimes difficult to work with

Fragile, not easy to bend or form

more prone to rust and corrosion

Unsightly appearance, unable to achieve the finish of stainless steel

application

Various types of carbon steel are suitable for a wide range of industries and sectors. Mild steel can be used in automotive body parts, pipes, construction and bridge components, and food cans. Medium carbon steel can be used for railway tracks, train wheels, crankshafts, gears and mechanical parts that require higher strength and toughness. Likewise, high carbon steel is used for cutting tools, spring high-strength wires and molds due to its hardness.

Can stainless steel be welded to carbon steel?

Although it is technically possible to weld these different types of metals together, the general consensus is that it is not advisable to do so. Welding of carbon and stainless steel is generally not performed because they have different levels of electrical conductivity. Carbon steel is usually preheated during resistance welding because it is more conductive and does not heat up as quickly as stainless steel. Therefore, reaching the correct soldering temperature is often extremely difficult. Therefore, it is generally recommended to weld similar steels together rather than mix and match.