Ndt of Steel Essay

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Lectures 21,22 NDT and Evaluation of Steel Structures Neithalath, Spring 2006, CE 455/555 Structural Damage: Assessment, Repair, and Strengthening The Chemistry The reaction between air and coke produces carbon monoxide (CO) This gas reduces the iron ore to iron Fe 2 O3 (s) + 3 CO (g) → 2 Fe (s) + 3 CO 2 (g) At the high temperature, limestone decomposes to calcium oxide and carbon dioxide The impurities react with this CaO to form slag Called Blast furnace slag – useful supplementary cementitous material in concrete Neithalath, Spring 2006, CE 455/555 Structural Damage: Assessment, Repair, and Strengthening Continuous Casting of Steel Neithalath, Spring 2006, CE 455/555 Structural Damage: Assessment, Repair, and Strengthening Steel Finishing – Final Shapes Neithalath, Spring 2006, CE 455/555 Structural Damage: Assessment, Repair, and Strengthening Which Iron is it? Cast iron Sandy texture (cast in molds filled with sand) Rounded internal corners, square external corners Typically hollow round shapes Wrought iron Material delamination at edges – corrosion Members by riveting iron plates Neithalath, Spring 2006, CE 455/555 Structural Damage: Assessment, Repair, and Strengthening Cast Iron structures Heavily used for columns Widely available Pig iron Good corrosion and fire resistance High compressive strength Cheaper than wrought iron Weak and unpredictable in tension and bending Brittle failure Neithalath, Spring 2006, CE 455/555 Structural Damage: Assessment, Repair, and Strengthening Age as an indicator of strength Before 1905 – YS – 25 ksi 1905-1932 – YS – 30 ksi 1933-1963 – YS – 33 ksi After 1963 – YS – 36 ksi YS of cast iron – 20 ksi Neithalath, Spring 2006, CE 455/555 Structural Damage: Assessment, Repair, and Strengthening History of structural steel Structural carbon steel – 1856 (Bessemer converter) 1884 – 1st steel I-beams, structural

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