7195

6701

كارشناسي ارشد

شناسايي و انتخاب مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1391

سيزده، 109ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليس

محمود مرآتيان

محمدرضا طرقي نژاد

10/8/91

كيوان رئيسي، قاسم ديني

1396/09/20

كتابنامه

مواد

مهندسي مواد

ID6701

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

111 Effect of Production Parameters on Uniformity of Metallurgical Properties and Coating Thickness of Hot Dip Galvanized Steel Strips at Mobarakeh Steel Complex Safoora Shahazamani s shahzamani@ec iut ac ir Date of submission 4 21 2012 Department of Material Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor M Meratian meratian@cc iut ac ir Abstract Hot dip galvanizing is one of the most common methods to protect steel strips from corrosion Nowadays because of usage of hot dip galvanizing strips in sensitive industries such as automobile the quality of them should be high One of the most determinant parameters in their quality is coating thickness uniformity and production costs are dependent of this In this research the effect of production parameters on uniformity and coating thickness of hot galvanized steel strips produced in Isfahan Steel Complex investigated Coating thickness in different part of strip width was measured with the use of microscopic observations and gravimetric methods Results showed the most important parameters affect coating thickness uniformity are line speed zinc bath temperature air knife parameters and strip vibrations Also the effect of coating thickness on uniformity on the metallurgical properties such as coating texture corrosion behavior and mechanical properties with the use of GDOES analysis X ray diffraction patterns optical and electron microscopic observations salt spraying and tafel polarization tests tension tests and forming limit diagrams was studied Microscopic observations showed that because of forming inhibition layer in the interface of coating and substrate while total coating thickness increased intermetallic layer thickness remain constant and on the other hand eta layer thickness with the 100 Zn composition increased Also with increasing coating thickness the texture transformed from basal plane to prismatic and pyramidal planes that this phenomenon caused reduction in coating corrosion resistance Salt sparing results expressed the time of appearance about 5 red rust in steel surface increased with coating thickening due to more cathodic protection from substrate In the galvanizing steel strips forming eta layer plays the rule of lubricant and decreases friction The results of Erickson tests showed that the width of safe area in forming limit diagrams being larger with increasing coating thickness demonstrator of better forming properties Finally the effect of production parameters such as line speed zinc bath temperature and air knife height on the coating thickness uniformity was assessed By increasing the line speed the immersion time decreases whereas withdrawal rate increases and affecting the coating thickness uniformity With increasing the bath temperature and so fluidity of molten zinc the outer surface part of coating will be thinner On the other hand with increasing in bath temperature zinc diffusion coefficient in the steel substrate increased and the thickness of coating internal part will be increased Increasing air knife height caused increasing on uniformity and coating thickness due to reduction molten viscosity Based on results the optimum line speed was 70 m min zinc bath temperature was 473 C and air knife height was 700 mm Keywords Hot dip galvanizing coating thickness Uniformity of metallurgical properties Line speed Zinc bath temperature Air knife

محمود مرآتيان

محمدرضا طرقي نژاد

كيوان رئيسي، قاسم ديني