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

2. 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

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

4. Sprocket Courtesy of Motorcycle Spares, accessed on 11/27/09

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

6. Smooth surface?
Sprocket, valley between teeth

7. 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

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

9. 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

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

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

12. -1045 steel -heat treatment -baked on paint from SunStar Products
under steel - off-road/mx/street.
accessed on 11/27/09

13. 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

14. 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 Vol. 35A, Iss. 4; pg. 1317, 8 pgs

15. References W.C. Leslie, The Physical Metallurgy of Steels, 1981
Damascus steel. ( 2009). In Encyclopædia Britannica. Retrieved December  2,  2009, from Encyclopædia Britannica Online:
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 Vol. 35A, Iss. 4; pg. 1317, 8 pgs