Classification of Steel Products produced in Steel Plants...

Classification of Steel Products produced in Steel Plants Steel products in general are classified as (i) castings, (ii) forged products, (iii) stamped products, (iv) bright products, (v) cold formed products, (vi) welded sections, (vii) wire and wire products, (viii) pipes, tubes, hollow sections and hollow bars, and (ix) powder metallurgy products. Steel products produced in steel plants are classified as per (i) stage of manufacture of the product, (ii) shape and dimensions of the product, and (iii) the product appearance. As per the stage of manufacture, the range of steel products produced in the steel plants are usually grouped into three main categories (Fig 1) namely (i) crude steel products, (ii) semi-finished steel products, and (iii) finished rolled steel products. Finished rolled steel products can be (i) hot rolled products, (ii) cold rolled products, and (iii) coated products.  Fig 1 Categories of steel products Crude steel products Crude steel products are either in the liquid state or in solid state. Liquid steel is normally used for the production steel castings. Crude steel in solid form was earlier considered as steel ingots which are produced by pouring liquid steel into iron moulds of a shape appropriate to the subsequent processing into semi-finished or finished steel products normally by hot rolling or forging. The shape of steel ingots usually resembles a truncated pyramid or truncated cone with the side surfaces may be corrugated and the corners more or less rounded. Steel ingots may be dressed and/or hot scarfed or cropped depending on the subsequent conversion requirements. Steel ingots can be distinguished based on their cross sections as (i) having a cross-section which can be square, rectangular (of width less than twice the thickness), polygonal, round, oval or shaped according to the profile to be rolled, (ii)...

Metal Coatings of Steels Sep18

Metal Coatings of Steels...

Metal Coatings of Steels  Metallic coated steels are defined as a steel substrates coated with a layer of zinc, Zn/Al (zinc/aluminum) alloy, Zn/Si (zinc/silicon) alloy, or pure Al etc. The schematic arrangements of metal coating structure with and without passivation is shown in Fig 1, Fig 1 Metal coating structure with and without passivation  Metal coatings of steels enhance the life and the performance of the steels. They provide the most effective and economical way of protecting steels against corrosion. Metal coated steels offer unique combination of properties which include high strength, formability, light weight, corrosion resistance, aesthetics, recyclability and low cost. There are several processes for metal coating of steels as given below. The hot dip coating process, whereby the steel strip is immersed in a bath of molten metal. The composition of the molten metal (Zn, Zn/Al, Al/Si, or pure Al etc.) determines the nature of the metal coating. The electro-galvanizing process, in which metal is deposited electrolytically on the cold steel strip. Coating under vacuum, such as PVD (physical vapour deposition), CVD (chemical vapour deposition) etc. Hot dip coating processes are the most popular processes for the metal coating of steel strips. Normally continuous coating lines are employed for the production of the metal coated steel products. Metallic coated steels produced in continuous coating lines have experienced a remarkable growth and continues to be used in increasingly varied new fields. This is due to their outstanding economic, technological and environmental advantages. .The wide range of metallic coated steel products available today meets the requirements of all sectors. The following are the parameters which govern the choice of the metal coated steel material. Quality or grade of the steel substrate Type of metal coating Mass or thickness of the metal coating Surface...