Steel Scrap and Scrap Sorting and Preparation Processes Jan23

Steel Scrap and Scrap Sorting and Preparation Processes...

Steel Scrap and Scrap Sorting and Preparation Processes Recycling of steel scrap is receiving increased impetus these days due to the focus of an emerging environmental initiative since the increased consumption of scrap reduces the needs for additional resource extraction and hence reduces the environmental impact. Recycling of steel scrap is also a part of wise management of iron resources. Recovery of 1 metric ton of steel from scrap conserves iron ore, coal, and limestone.  As per the world steel association, the integrated steelmaking route, based on the blast furnace (BF) and basic oxygen furnace (BOF), uses 1,400 kg of iron ore, 800 kg of coal, 300 kg of limestone, and 120 kg of recycled steel to produce 1,000 kg of crude steel and the electric arc furnace (EAF) route on average uses 880 kg of recycled steel combined with varying amounts of other sources (DRI, hot metal, and granulated iron), 16 kg of coal and 64 kg of limestone, to produce 1,000 kg of crude steel.  On an average, recovery of 1 ton of steel from scrap conserves an estimated 1,030 kg of iron ore, 580 kg of coal, and 50 kg of limestone. Steel scrap recycling also saves the energy consumption.  In the production of steel, 99.9 % of scrap melted is consumed in the production of new steel while producing negligible environmentally undesirable waste. Steel scrap is classified in three main categories namely (i) home scrap, (ii) new scrap, and (iii) old scrap depending on when it becomes scrap in its life cycle. Home scrap is the internally generated scrap during the manufacturing of the new steel products in the steel plants. It is also known as runaround scrap and is the material in the form of trimmings or rejects generated...

Steels and Cast irons and their Essential and Incidental Elements...

Steels and Cast irons and their Essential and Incidental Elements Steels and cast irons are basically alloys of iron and different other elements in the periodic table. The vast majority of steels and all cast irons contain carbon as a principal alloying element. As a general definition, steel is an alloy of iron, carbon (less than 2 % C), and other alloying elements which is capable of being hot and/or cold deformed into various shapes. On the other hand, cast iron is an alloy of iron, carbon (higher than 2 % C), and other alloying elements and is not generally capable of being hot and/or cold deformed. A cast iron is used in its cast form. Steels and cast irons are the most widely used and least expensive metallic materials. There are several thousands of different steel compositions presently available. A vast variety of terminology is used to differentiate different types of steels. In fact, the way the steels are classified sometimes is quite confusing even to the regular user of steels. However, in many cases, the steels fall into a limited number of well-defined classes. Generally, the carbon and low alloy steels come under a classification system based on composition. The high alloy steels (the stainless, heat resistant, and wear resistant steels, etc.) are being classified according to many different systems, including composition, microstructure, application, or specification. The easiest way to classify steels is by their chemical composition. Different alloying elements are normally added to iron for the purpose of attaining certain specific properties and characteristics. These elements include, but are not limited to, carbon, manganese, silicon, nickel, chromium, molybdenum, vanadium, niobium, copper, aluminum, titanium, tungsten, and cobalt. The general category of carbon and low alloy steels encompasses plain carbon steels, alloy steels,...

Steel and its types

Steel and its types Steel is basically an alloy of iron and carbon to which sometimes other elements are added to achieve certain properties for specific performance of the steel. It is the most common material which the people come into contact with every moment, all the day and every day. There is hardly any object that people use today which does not contain steel or which is not created with equipment made of steel. In fact, today it is hard to imagine a life without the use of steel in some shape or form.  One has to just think of what would be missing in everyday life if there is no steel. Mass production of steel started late in the nineteenth century. From that time onwards steel has become the material of choice in most of the applications which make the daily lives of the people possible. This position of steel is due to its versatility, strength, and recyclability. The versatility of steel is well known. It can be used in diverse applications which includes transportation, infrastructure, building structures etc. on one side and sewing needles, screws for laptops, mother board sheets for mobile phones, springs for wrist watches and many others such smaller applications. Ballpoint pens rely on a steel sphere less than 1 mm in diameter to dispense ink. Steel can also be used in a wide variety of atmospheres which include extremes of cold and hot climates as well as in both arid and wet climates. World today depends on the strength of steel. Steel makes it possible to build skyscrapers and long span bridges since it has strength, rigidity and durability. Tankers and bulk carriers which help in moving resources across the world are made of steel. Wind mills...

Welding of Carbon and Low Alloy Steels and Hydrogen Induced Cracking Sep23

Welding of Carbon and Low Alloy Steels and Hydrogen Induced Cracking...

Welding of Carbon and Low Alloy Steels and Hydrogen Induced Cracking Arc welding is a process by which steels are joined by coalescence. Normally the process uses a compatible filler material. Before a well-bonded joint is produced, the joint surface is to be heated above the melting temperature in order to completely fuse with the weld metal. Though the metallurgical reactions which involve melting, solidification, and solid-state transformation are not unusual, the temperatures and cooling rates observed are severe. Active gases also are present and can dissolve in the fused steel. Fluxes are introduced to alloy with and protect the weld metal. Generally, joints are rigid and restrain dimensional changes caused by shrinkage and solid-state transformations, producing residual stresses of yield-strength (YS) magnitude. Since the metallurgical changes do not occur under equilibrium conditions, and since the stresses are high, many of the reactions can take place in either or both the weld metal and the heat affected zone (HAZ) of the steel and can produce defects that weaken their soundness. Because of the tremendous variability of the welding processes, it is difficult to provide much detail about the exact mechanisms involved or the corrections that can be made. Furthermore, many corrective measures are obvious once most defects are explained. One problem, which relates to hydrogen (H2), is not simple. Since this problem is becoming more relevant as more high-strength, low-alloy (HSLA) steels are being welded, the subject of hydrogen-induced cracking (HIC) is very important. Carbon (C) and low alloy steels are welded since they have widespread application and good weldability. This usefulness is mainly due to the metallurgical characteristics of the iron (Fe) base system. The characteristic includes the ability to undergo allotropic (microstructural) transformation which allows the opportunity for hardening and strengthening through...

Continuous casting of steel billets Mar19

Continuous casting of steel billets...

Continuous casting of steel billets Continuous casting of steel is a process in which liquid steel is continuously solidified into a strand of metal. Depending on the dimensions of the strand, these semi-finished products are called slabs, blooms or billets. Steel billet has a square cross section with one side normally 150 mm or less. It is a feed material for rolling of steel in light section mills, bar mills, and wire rod mills. Steel billets are also used in forging of certain products. The process of continuous casting was invented in the 1950s in an attempt to increase the productivity of steel production. Previously only ingot casting was available which still has its benefits and advantages but does not always meet the productivity demands. Since then, continuous casting has been developed further to improve on yield, quality and cost efficiency. Continuous casting of steel is now the method of choice by all steel producers replacing the old method of ingot casting. Distinguished by its many advantages, this process has gone through many improvements and was and still is the subject of wide range of studies both empirically and mathematically. Continuous casting of steel billets is one of the type of continuous casting adopted in steel industry, by which, steel billets are produced continuously and simultaneously. This type of process requires great control of operating parameters in order to produce sound and continuous billets. The process can be divided into a number of steps starting by pouring the hot liquid steel from the steelmaking furnace into the ladle, where the steel chemistry is being adjusted in secondary steelmaking, then pouring into the distributor (tundish), and from the distributor into the casting mould. Solidification of steel begins in the copper casting mould by indirect cooling,...