Sunday 20 July 2008

Ti vs. Chromo

Lots of talk is going around about which is stronger, and what the pros and cons are... from what I can see:

Ti - 
Pros: Stonger. Tighter compound, therefore it is more rigid and less likely to flex. It is also much lighter.
Cons: Expensive. Hard to re-weld and repair. Prone to cracking/snapping when k.o.'d

Chromo - 
Pros: Cheap. Looser compound, therefore is more flexible.
Cons: Weaker. Heavier. Prone to bending (under less equivalent pressure)

The main thing that people are bitching about is the price of Ti, and fair enough whatever its expensive shit. People are also saying that the bike companies are skimping on the amount of metal used and therefore the frame still has flex and will break easier (cost cutting), but how the fuck would they know this - as if that isn't a guess!
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Here are some specs on the metals (Ti is obviously stronger)

4130 (Chromoly) Normalized Alloy Steel - Most frames are made of this
Minimum Properties Ultimate Tensile Strength, psi 97,200
Yield Strength, psi 63,100
Elongation 25.5%
Rockwell Hardness B92

4130 (Chromoly) Annealed Alloy Steel
Minimum Properties Tensile Strength, psi 81,200
Yield Strength, psi 52,200
Elongation 28.2%
Rockwell Hardness B82
Chemistry Iron (Fe) 97.3 - 98.22%
Carbon (C) 0.28 - 0.33%
Chromium (Cr) 0.8 - 1.1%
Manganese (Mn) 0.4 - 0.6%
Molybdenum (Mo) 0.15 - 0.25%
Phosphorus (P) 0.035% max
Sulphur (S) 0.04% max
Silicon (Si) 0.15 - 0.35%

6Al-4V (a/k/a Grade 5) Titanium - Eastern Ti-Grim Reaper
Minimum Properties Ultimate Tensile Strength, psi 138,000
Yield Strength, psi 128,000
Elongation 14%
Rockwell Hardness C36
Chemistry Titanium (Ti) 90%
Aluminum (Al) 6%
Vanadium (V) 4%
Iron (Fe) 0.25% max
Oxygen (O) 0.2% max

6Al-4V ELI (extra low interstitial) Titanium
Minimum Properties Ultimate Tensile Strength, psi 125,000
Yield Strength, psi 115,000
Elongation 15%
Rockwell Hardness C35
Chemistry Titanium (Ti) 90%
Aluminum (Al) 6%
Vanadium (V) 4%
Iron (Fe) 0.14% max
Oxygen (O) 0.13% max


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