The Microstructure of 35 Steel
35 steel is a ferritic alloy steel of low carbon content, with a very specific combination of properties. This alloy is widely used in a number of different applications, from hydraulic and mechanical components, to bearings and fasteners. It also finds use in certain specialized welding processes and some pressure vessel production processes. To understand its uses and its performance, it is important to understand the microstructure of 35 steel, which is composed of a majority of ferrite grains and a small but important amount of residual elements such as sulphur and phosphorus.
The microstructure of 35 steel is the result of annealing, a process of heating followed by cooling, which helps to homogenize its composition. The typical annealing temperature range used for 35 steel is between 1000 and 1050 °C, and the cooling is usually done in an inert atmosphere such as nitrogen or argon. The annealing reduces the amount of residual elements and produces a more homogeneous microstructure.
When looking at the microstructure of 35 steel under a microscope, the majority of grains present are ferrite grains. These grains have a typical size range of 3-5 microns, and when examined by optical microscopy, reveal that the structure consists of small spherical objects with a white or light grey colour. The residual elements present in the steel, however, are still visible; the sulphur and phosphorus are visible as small rods, often located on the grain boundaries.
The ferrite grains, when examined further, reveal themselves to be cellular in nature and are composed of several small lattices, which form a cylindrical shape. The lattices themselves are arranged in an alternating left and right pattern and display either a rounded or a squared appearance. The ferrite grains also contain a small amount of carbon which contributes to their hardness and helps improve the steels creep resistance.
The presence of residual elements in the microstructure of 35 steel is important in a number of ways. The sulphur and phosphorus act as impurities, modifying the structure of the ferrite and creating complex distributions of lattices inside the ferrite grains. This influences the strength and corrosion resistance of the steel, as well as its weldability and machinability. Finally, the microstructure of 35 steel can also be useful in certain heat treatments and production processes to obtain certain desired properties.
In conclusion, the microstructure of 35 steel is an important aspect in understanding its performance. It consists of a majority of ferrite grains and a minor amount of sulphur and phosphorus. These residual elements modify the microstructure and can have an influence on the mechanical and corrosion properties of the steel. Also, the presence of these elements allows for certain specialized heat treatments and production processes to obtain the desired results.
