BASIC METALLURGY FOR WOODTURNERS

Copyright © 2011 John W. Cobb What Is Steel? Iron soft little resistance to bending wears quickly poor at holding an edge Plus one or more other elements Carbon and Tungsten are common

Copyright © 2011 John W. Cobb Types of Steel Mild Steel 0.15% to 0.25% 1 Medium Carbon Steel0.25% to 0.50% High Carbon Steel0.60% and above Tool Steel0.80% to 1.25% WOOD TURNING TOOLS Alloy steels (alloys of iron and other elements) Percent carbon

Copyright © 2011 John W. Cobb Carbon Steel Carbon added while iron is molten Carbon combines with iron to form iron carbide platelets (Fe 3 C) which are imbedded in an iron matrix

Copyright © 2011 John W. Cobb Properties of Carbon Steel Very hard Somewhat brittle Takes a fine edge Resistant to wear Resistant to bending Takes and holds an excellent edge SENSITIVE TO HEAT Requires careful grinding

Copyright © 2011 John W. Cobb Other Types of Steel High Speed Steel Woodturning tools Drill bits Milling bits Very high heat tolerance!

Copyright © 2011 John W. Cobb High Speed Steel M2 HSS is an alloy containing: Carbon0.82% Manganese0.25% Silicon0.25% Chromium4.25% Tungsten6.25% Vanadium1.90% Molybdenum5%

Courtesy Leonard Lee and The Taunton Press

Copyright © 2011 John W. Cobb Relative Hardness of Selected Materials 1 Material Mohs Scale Rockwell Scale (C) Talc1n/a Magnesia, Cabinet scrapers2+38 Apatite, Handsaws542 Nickel, Hand Scrapers5+51 Cabinet making tools High Carbon & HSS tools Quartz764

Copyright © 2011 John W. Cobb Relative Hardness of Selected Materials 2 MaterialMohs Scale Rockwell Scale (C) Tungsten carbide9+ Aluminum oxide9+ Silicon carbide9+ Cubic Boron Nitride (CBN)9+ Diamond10