Urban Steel Scavenging Guide

Used in

• Chapter 2 The City Is a Mine

The rows that check it

• 12 confirmed
• 1 unresolved
• 4 marked for safety

• I1 confirmed Safety Zinc on galvanised steel boils at red heat; grinding, welding or forging it gives metal fume fever: shivers, metallic taste, fever, nausea in 4 to 10 hours, lasting a day or two
• I11 unresolved Safety Manganese (Hadfield) steel: non-magnetic, unhardenable, destroys files and saws; digger teeth, crusher jaws, rail crossings
• I8 confirmed Safety Never quench an unknown steel in water: it cracks; warm oil
• K6 confirmed Safety Never quench a file, spring or blade in water
• I19 confirmed Mild steel under 0.3 % C cannot be hardened; medium 0.3 to 0.6; high 0.6 and up for edges
• I27 confirmed EN 10027 stamps: S plus yield strength, C plus carbon in hundredths, 1.xxxx material numbers; 1.7176 = 55Cr3 spring steel
• I28 confirmed Leaf springs 51CrV4 / 55Cr3 at 0.47 to 0.64 % C; coil springs 61SiCr7; axles medium; bearings 100Cr6 at 1.0 % C, 1.5 % Cr; files W1 at 1.0 to 1.2 % C; rail R260 at 0.62 to 0.80 % C
• I29 confirmed File skates at about 60 HRC and bites under 40
• I30 confirmed Spark test: mechanism (CO burst), dim light, grind past skin, known 1018 and 1084 pieces, 45° light pressure; the stream table by carbon class, chromium orange, stainless yellow …
• I31 confirmed Decarburised skin a millimetre or more to grind off
• I32 confirmed File fracture test: through-hardened snaps with fine silky grey grain; cased bends and shows glassy rim round fibrous core
• I33 confirmed Curie point 770 °C, magnet lets go whatever the carbon; harden a shade above, bright cherry red
• K17 confirmed 1084 is 0.80 to 0.84 % carbon, hardens in fast oil from a plain forge with no soak; leaf spring 5160 about 0.6 % C with chromium, deeper hardening, slow oil, cracks in fast; file …

In the Index

Iron and steel Tools and their making The field and the rotation