Btec Level 3 Mechanical Engineering
Assessment 2 – 40580/02
1a)
Plain carbon steel is essentially an alloy of iron and carbon which also contains manganese and a variety of residual elements. These residual elements were either present within the raw materials used in the production process e.g. iron ore and scrap steel additions, or they were added in the production process for a specific purpose, e.g. deoxidization by means of silicon or aluminium. Hence they are called residual elements to distinguish them from alloying elements that are deliberately added according to specified minimum amounts. The term “cleanliness” refers to the amounts of various phases such as oxides, sulphides and silicates that can be present in steel. The smaller the amount of these phases, the cleaner the steel. For many years steels have been produced by casting the molten steel into moulds and allowing it to solidify into ingots which were then processed by rolling etc. steel produced by ingots is subdivided into four categories according to the deoxidization process used. These categories are rimmed, capped, semi-killed and killed steel. When un-deoxidized steel is cast into an ingot, carbon monoxide is evolved during solidification because the solubility of oxygen decreases as the temperature decreases.
1b)
Steels that contain specified amounts of alloying elements, other than carbon and the commonly accepted amounts of manganese, copper, silicon, sulphur and phosphorus are known as alloy steels. Alloying elements are added to change mechanical or physical properties. Alloy steels are melted together in an electric furnace. This step usually involves 8 to 12 hours of intense heat. Next, the mixture is cast into one of several shapes including blooms, billets and slabs. After various forming steps, the steel is heat treated and then cleaned and polished to give it the desired finish. The semi-finished steel goes through forming operations, beginning with hot rolling, in which the steel is heated and
1a)
Plain carbon steel is essentially an alloy of iron and carbon which also contains manganese and a variety of residual elements. These residual elements were either present within the raw materials used in the production process e.g. iron ore and scrap steel additions, or they were added in the production process for a specific purpose, e.g. deoxidization by means of silicon or aluminium. Hence they are called residual elements to distinguish them from alloying elements that are deliberately added according to specified minimum amounts. The term “cleanliness” refers to the amounts of various phases such as oxides, sulphides and silicates that can be present in steel. The smaller the amount of these phases, the cleaner the steel. For many years steels have been produced by casting the molten steel into moulds and allowing it to solidify into ingots which were then processed by rolling etc. steel produced by ingots is subdivided into four categories according to the deoxidization process used. These categories are rimmed, capped, semi-killed and killed steel. When un-deoxidized steel is cast into an ingot, carbon monoxide is evolved during solidification because the solubility of oxygen decreases as the temperature decreases.
1b)
Steels that contain specified amounts of alloying elements, other than carbon and the commonly accepted amounts of manganese, copper, silicon, sulphur and phosphorus are known as alloy steels. Alloying elements are added to change mechanical or physical properties. Alloy steels are melted together in an electric furnace. This step usually involves 8 to 12 hours of intense heat. Next, the mixture is cast into one of several shapes including blooms, billets and slabs. After various forming steps, the steel is heat treated and then cleaned and polished to give it the desired finish. The semi-finished steel goes through forming operations, beginning with hot rolling, in which the steel is heated and