Things to Know About Hot Rolled Steel Sheet

                In the Steel Industry, rolling is often referred to the metal forming process in which steel stock is passed through one or more pairs of rolls to decrease the thickness. This helps in making the metal sheet uniform. Imagine rolling dough into pancakes - that would be the simplest example to explain how steel sheets are formed. Rolling sheet metals has a lot of commercial applications as the rolled sheets can be used in different ways. 

                The process of rolling can be classified into two major types, depending on the temperature of the metal rolled. When the temperature of the metal sheet is above its recrystallization temperature, the process of rolling is called as hot rolling and the steel sheet thus formed becomes a hot rolled steel sheet. When the temperature of the metal is below its recrystallization temperature, the process is called as cold rolling and the steel sheet thus formed becomes a cold rolled steel sheet. In terms of applications, hot rolling processes more steel than any other manufacturing process.

                Hot Rolled Sheets generally have less deformation induced residual stress and little directionality in their mechanical properties. In certain instances though, non-metallic inclusions can have some directionality, especially sheets less thick than 20mm. Hot rolled steel also have a wider tolerance for the amount of induced carbon compared to a cold rolled sheet. Though a few blacksmiths might find this problematic, but the affordability of hot rolled sheets make them quite popular in the market. 

               One precaution that needs to be taken care of during hot rolling is that the temperature of the metal needs to be uniform. This is important because if the temperature of the sheet is not uniform, the flow of the material will occur more in the warmer parts. If the temperature difference is too much, cracking and tearing can occur as well. 

              The process of hot rolling is commercially used to produce steel sheets for application in rail tracks, truck frames, automotive wheels, pipe and tubular, water heaters, agriculture equipment, strappings, stampings, compressor shells, rail car components, wheel rims, metal buildings, railroad-hopper cars, doors, shelving, discs, guard rails, automotive clutch plates.

Types of Sheet Piles and it’s Usages

                             The system of Sheet piling, in which Steel sheet sections with interlocking edges are used in earth retention and excavation support retaining soil, has been in practice for many years now. Sheet pile walls have been used to support excavations for basements, foundations, below grade parking structures, pump houses, and to construct cofferdams, seawalls and bulkheads. The technique is simple – sheet piles are installed in a sequence to design depth along the planned excavation perimeter or seawall alignment. These sheet piles, interlocked at the edges, form a wall for lateral earth support with reduced groundwater inflow. For additional lateral support, anchors also are included sometimes. 

      

                       

                             The installation of sheet piles is achieved using vibratory hammers. Depending on the soil, an impact hammer can be used to complete the installation if it is too hard or dense. If vibrations are a concern at certain sites, the sheets can be hydraulically pushed into the ground. The geometry of the sheet pile section and the soils it is driven into play an important factor in contributing to the performance of the section. This is because the pressure is transferred from the high side of the wall to the soil in front of the wall.

                              Depending on the necessity of the project, sheet piles can be temporary or permanent. Permanent steel sheet piles are used in providing a long service life, they remain in the ground to serve as retaining structures for as long as they can. The temporary sheet piles are designed to retain only until the project’s end, like in constructions. 

                              Steel sheet piles can also be categorized based on their manufacturing method. Sheet piles that are formed in a molten state and rolled flat while still hot are known as Hot Formed Sheet Pile. Sheet piles that are formed by pressing steel into a sheet in a cold state are known as Cold Formed Sheet Pile. Hot formed sheet piles have a variable metal composition and hence are a little difficult to machine. They are of lesser quality when compared to Cold formed sheet piles which have a more homogenous composition allowing better heat conductivity and are easier to machine. Hot formed sheet piles are larger in size and have a wider range of strengths than cold formed sheet piles.

                              The interlock at the edges of the sheet piles is another important distinction between a hot formed sheet pile and a cold formed sheet pile. Since hot formed sheet piles are produced from steel at high temperatures, the interlock tends to be tighter than that in the cold formed steel piles. On the other hand, cold formed steel piles have looser interlocks. Hence, they are not recommended in extremely hard driving conditions or for walls requiring low permeability.         

                            Steel sheet piles, both hot formed sheet piles and cold formed sheet piles, are a sustainable option because recycled steel is used in their construction and at the end of the project, the piles can be extracted and the steel can be reused.