The defence industry requires materials with certain characteristics that help equipment to function properly and perform consistently. For steel, its use in this industry stems from its strength, corrosion and heat resistance, and durability, being found in tanks, military aircraft, and naval vessels. There are a number of different types of steel available, such as stainless steel, ballistic steel, and high-strength low-alloy steel.
However, the steel we're going to focus on today is S235structural steel. This grade of low carbon structural steel is implemented in many ways in the defence industry, from the structural components of military buildings to armoured personnel carriers and ship hulls. Join us as we explain more about S235 steel, alongside its variations and the reasons it should be your choice of steel for defence applications.
What is S235 Steel?
S235 is a grade of structural steel with a low carbon content, its maximum amount being 0.22% by weight. Its weldability, formability, and strength are all thanks to its reduced carbon content. This steel also has other mechanical attributes, including:
- A tensile strength between 360 – 510 MPa
- A hardness of 100 – 154 Brinell
- Good impact resistance.
The characteristics of S235 steel depend on its composition. Therefore it's crucial that the steel's production is meticulously controlled to establish the right attributes. Below are the elements, and their maximum percentages, utilised when forming S235 steel:
- Carbon (<0.22%): Ensuring the steel can undergo welding and does not need special precautions.
- Silicon (<0.5%): Supporting galvanization to make sure the steel can deliver corrosion protection.
- Manganese (<1.60%): Increasing the steel's hardenability and strength.
- Sulfur (<0.040%): Using a minute amount of sulfur can enhance weld penetration and machinability.
- Phosphorus (<0.040%): Applying phosphorus can improve the tensile and yield strength of the steel.
The Categories Of S235 Steels
Many variances of S235 structural steels are available that have distinct attributes and alterations in their chemical compositions. These include:
S235JR: A frequently used type of steel, S235JR is known for its weldability, machinability, durability, and wear-resistance. Its "JR" suffix indicates that its minimum impact energy is 27 joules and that it underwent an impact test at 20°C. S235JR tends to be applied within building structures, oil and gas platforms, and components for transportation.
S235J0: This type of steel has similarities to S235JR. However the main difference between them is that S235J0's impact testing is conducted at 0°C. It has good machinability, formability, and adequate tensile strength. S235J0 can be used in metal structures and within general engineering components.
S235JRC: What makes S235JRC stand out is its applicability to cold forming procedures. It has good weldability and does not require pre-heating. Transmission towers and bridges are both examples of where S235JRC can be applied.
When considering which steel to pick, make sure to think about factors including welding requirements, fabrication techniques, and operating temperatures.
Reasons For Using S235 Steels In The Defence Industry
Weldability
S235 structural steels, like S235JR, have great weldability because of their reduced carbon content. This low level of carbon can decrease the chance of the structures becoming brittle when welding occurs. S235JR does not even require heat treatment for it to be welded to a variety of structural steels. This makes it extremely useful for the defence industry, as it can be utilized for producing complicated structures and machinery that require various grades of steel.
Impact Resistance
The impact resistance of S235 structural steels is another useful attribute that can be applied in the defence industry. Not only can these steels offer different amounts of impact resistance, meaning that the choice of steel can be made depending on whether the material will suit its operating conditions, but this attribute can deliver protection for both the apparatus and personnel. Impact resistance is an essential quality to have in the defence industry when protecting structures against impacts or shocks. A variety of defence equipment needs S235 steel because of its impact resistance. For instance, naval vessels require it within their ship hulls to mitigate the effects of waves or explosions.
Corrosion Resistance
Applying galvanization helps S235 structural steel to provide corrosion resistance. When utilised in the defence industry, the steel will be defended by its coating. Therefore it will be able to improve the lifespan of structures and equipment. The defence industry can make use of galvanized S235 steel. It can offer protection against marine corrosion, something which may occur in salt-intensive areas, and stress corrosion cracking, that may appear in load-bearing structures.
Strength
As S235 steel has 235 MPa as its yield strength, alongside 360-510 MPa as its tensile strength, it can offer both a robust load-bearing capacity, in relation to structural components, and resilience against stress. Each of these properties mean that S235 steel can be applied as structural components. Examples of where this steel is used include bridges and buildings. It's also utilised in military vehicles that need defending against explosive devices.
GNEE Can Help You Obtain S235 Steel
The attributes of S235 steels are what make them so useful for the defence industry. Already, these steels are used in a number of defence applications. They can be found in armored vehicles, military bases, aerospace components, and naval vessels. Try these steels for yourself and see the benefits they can deliver.
If you want to learn more about GNEE's products, you can send an email to alloy@gneesteelgroup.com. We are more than happy to assist you.
What is the difference between S275 and S235 steel?
Moderate Loads: For applications like general construction of buildings or supports, S275 offers a balance of strength and cost. Light Structures or Non-Load Bearing Components: S235 is suitable for applications where structural strength is less critical, like smaller frames, beams, or lightweight structures.
What is the equivalent of S235 steel?
S235 steel is a widely used carbon structural steel, and its equivalents depend on the specific standard, but common examples include ASTM A36, JIS SS400, DIN ST37-2, and GBT Q235B. The "S235" designation means it is a structural steel (S) with a minimum yield strength of 235 MPa, and the suffix (like JR) indicates specific properties like toughness at 20°C.
Is S235 equivalent to A36?
The term "235" refers to the minimum yield strength (MPa) for steel thickness less than 16 mm. The "JR" indicates the energy-related quality level of the Charpy impact test (27 J, 20℃ temperature). ASTM A36 material is equivalent to steel S235JR.
