Microstructure of a Steel Sprocket and Anodizing Aluminum Ian Buchanan and Kris Magri Santa Rosa Junior College Engr 45, Younes Ataiiyan December 07, 2009

Authors Ian Buchanan is a Civil Engineering major, hoping to work in construction Kris Magri is a Mechanical Engineering major who plans to work in robotics

Part I: Microstructure of a steel sprocket Imperfections, carbon content, and banding

Sprocket Courtesy of Motorcycle Spares, accessed on 11/27/09 http://www.te-motorcyclespares.co.uk/images/Chain%20&%20Sprocket.jpg

Procedure Desired cuts Mounted in bakelite Sanded and polished Nitric acid solution (Nital) etch Observe and report

Smooth surface? Sprocket, valley between teeth

Carbon Content -estimated as 0.3 to 0.6% carbon Sprocket, bottom of tooth -estimated as 0.3 to 0.6% carbon -using chart from materials lab

Banding Steel sprocket .35%C steel, hot-rolled, courtesy W.C. Leslie, The Physical Metallurgy of Steels, 1981

Mn and C Segregation For cast steels, Mn segregates into a branched structure that flattens out upon hot rolling Mn blocks C in austenite Pearlite forms at concentrated areas of Mn and C

X-ray photographs Mn Branching After rolling courtesy W.C. Leslie, The Physical Metallurgy of Steels, 1981

Banding Anisotropy “Peeling” Sprocket, top of tooth courtesy W.C. Leslie, The Physical Metallurgy of Steels, 1981

-1045 steel -heat treatment -baked on paint from SunStar Products http://sunstar-mc.com/Products.aspx under steel - off-road/mx/street. accessed on 11/27/09

Damascus Steel Hard steel with a water-like appearance from layers of differing carbon content Unlike banding, different phases are macroscopically visible Bars of steel repeatedly doubled over and forge welded to achieve differing layers Modern pattern welded damascus steel, knife blade, from http://damascus.free.fr/f_damas/f_quest/i_steel/dmsc_k_.jpg

Banding and Anisotropy fracture happens parallel to the bands in tensile sample Stainless steel with the banding microstructure Courtesty of A C Stauffer, D A Koss, J B McKirgan. “”Microstructural Banding and Failure of a Stainless Steel”. Metallurgical and Materials Transactions: A : Physical Metallurgy and Materials Science. Warrendale: Apr 2004. Vol. 35A, Iss. 4; pg. 1317, 8 pgs

References W.C. Leslie, The Physical Metallurgy of Steels, 1981 Damascus steel. ( 2009). In Encyclopædia Britannica. Retrieved December  2,  2009, from Encyclopædia Britannica Online: http://search.eb.com/eb/article-9028636 A C Stauffer, D A Koss, J B McKirgan. “”Microstructural Banding and Failure of a Stainless Steel”. Metallurgical and Materials Transactions: A : Physical Metallurgy and Materials Science. Warrendale: Apr 2004. Vol. 35A, Iss. 4; pg. 1317, 8 pgs