H Type Carbon Steel for Construction

Carbon adds hardness and strength to steel. It also increases brittleness and reduces weldability (above 0.25% C).

Hydrogen embrittlement is a serious concern with carbon steels. The tensile properties of steel in the presence of hydrogen are highly dependent on test conditions and testing procedures. Because of these variations, mechanical property data from various tests may be difficult to compare.

Strength

The main advantage of using H type carbon steel for construction is that it is a very strong material, able to withstand immense amounts of force. This makes it perfect for use in construction projects such as bridges and skyscrapers. In addition to being extremely strong, H type carbon steel is also very durable and resistant to corrosion.

Low carbon steels have a very high work hardening rate, which means they are extremely versatile and can be formed into a wide variety of shapes. They are also surprisingly ductile, especially when additional alloys are added to the material. These can include chemical additives such as manganese, which helps to increase the strength of low carbon steel without increasing its weight.

High carbon steels have a much higher carbon content than low or medium carbon steels, with levels of around 0.6% to 1.5%. This makes them very strong and hard, but also less ductile than mild steel. High carbon steels are often used for items that require a high level of strength such as knife blades and hand tools.

Some high carbon steels are susceptible to hydrogen embrittlement when subjected to very cold temperatures. This can result in reduced tensile strength, but is not usually an issue H type carbon steel for construction applications. Testing methods to evaluate hydrogen embrittlement vary significantly, so property data from different tests should be interpreted with caution.

Weldability

Carbon steel can be welded, but it is more prone to weld-related cracking than medium or low carbon varieties. To prevent this, the steel must be properly heat treated before and after welding. This process helps reduce stress, increases ductility and improves corrosion resistance. It also helps prevent oxidation from the weld zone.

Depending on the specific application, a higher carbon content can provide better hardness and abrasion resistance. For instance, tool steels have a high carbon content and are used to make hammers, cutting tools, milling cutters, drills and metal-cutting machine tools. They also have good machinability and high strength at elevated temperatures.

In addition to the benefits listed above, some carbon steel grades are also better suited for cold forming and bending applications. These grades are typically hot rolled and then subjected to a final recrystallization anneal, which refines the lamellar spacing and crystallographic orientation of the grains. This is particularly important for reducing non-pearlite structures that can cause cracking during the forming process.

High-carbon steels are also well suited for welding, but they are more susceptible to weld-related cracking than low or medium carbon varieties. This can be prevented by proper heating prior to and after welding, the use of low hydrogen electrodes and by controlling the welding heat input. These techniques also help to avoid any dislocations or deformations in the weld zone.

Corrosion Resistance

Mild carbon steels generally have good corrosion resistance, however this can be affected by a number of factors, including hydrogen content, temperature, chemical composition and microstructure. The presence of hydrogen can result in the initiation and progression of weld cracking, intergranular corrosion and embrittlement. This can result in serious damage to steel structures and resulting environmental contamination. It can also cost substantial sums for restoration, repair, replacement and protection. Corrosion of metal is responsible for a significant number of disasters such as the oil pipeline explosion in Qingdao, China in 2013, which killed 62 people and destroyed over 1,600 homes; and the failure of an El Paso Natural Gas natural gas pipeline at Fukushima, Japan in 2011, which caused destruction to buildings and polluted the surrounding sea and soil.

Low carbon steels have good resistance to corrosion in the lower temperatures range but this is not true of the higher grades, which have poor corrosion resistance. The lower chromium content in the higher grades results in less resistance to aqueous corrosion and the increased carbon content reduces air corrosion resistance.

H grades are often supplied in plate or pipe but are also available as structural sizes of angle, bar and channel. They can be used where high tensile strength is not required, although they will lose some of their long term creep strength in these applications. They are susceptible to sensitisation if held in the temperature range of 500-850 degC and will show reduced aqueous corrosion resistance if this happens.

Ductility

The ability of a material to stretch before it breaks is known as ductility. Steels with high ductility can be used for construction, as they can be welded to form a stronger and more resilient structure. This is a key benefit when compared to concrete, which has lower ductility and is therefore more likely to crack under tension or compression.

Low (or mild) carbon steel is a common and inexpensive option for many engineering applications, including structural parts and mechanical components. It has good formability and weldability, and can be further strengthened with additional alloys and heat treatments to meet specific application requirements.

Medium carbon steel offers a balance between low and high carbon steels, combining greater strength and hardness with improved ductility. It is often used to manufacture machinery components like shafts and gears, and can be further strengthened with alloy additions low carbon steel bar and heat treatment to increase its toughness for use in applications where it will experience heavy stress.

Higher-carbon steels offer the greatest strength and hardness of all carbon plate grades, but have significantly reduced ductility. They are often further treated to enhance hardness and wear resistance, making them ideal for applications that will see a great deal of stress, such as cutting tools and power-saw blades. The increased carbon content also decreases the corrosion resistance of these steels, and they may be susceptible to hydrogen embrittlement if water quenched.