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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
girdraulic blades-straightening
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<blockquote data-quote="Pete Appleton" data-source="post: 8654" data-attributes="member: 145"><p><strong>Facts and figures</strong></p><p></p><p>Looks as though the old man beat me to this as I have to work for a living and he keeps reminding me that he should be retired by now. But here is my contribution:-</p><p></p><p>I recently did a bit of research on this matter as the fork blades that I used in building my Rapide had suffered a fatal encounter with the side of a car, back in the sixties.</p><p></p><p>To start with we tried an odd and severely bent blade that was lying around the shed. When put under the press, with no pre-treatment, it put up a lot of resistance and then broke. </p><p></p><p>Consultation with my friendly, local heat treater produced some suprising information :-</p><p></p><p> Annealing of aluminium alloy is totally the reverse to steel. You take the aluminium up to a temperature, dependant on the chemical composition of the alloy, and then quench it.</p><p></p><p> Salt bath solution is just one type of heat treatment furnace. Mine was done in an air blast furnace with no ill effects.</p><p></p><p> Once annealed the alloy will then begin to re-harden with time. This once again depends on temperature and composition. The higher the temperature the faster the hardening will take place. I was advised to carry out the hardening within a day of the annealing and to keep the blades cool, i.e. not in front of a heater, until we had finished straightening.</p><p></p><p> Re-hardening is known as precipitation hardening or artificial ageing. This involves heating the material to a specific temperature for a time and then allowing it to cool slowly.</p><p></p><p>I sent a piece of the first, broken, blade to 'Bodycote materials testing Teeside' for destructive analysis. The results were as listed at the end of this. This seems to equate to a 2000 series aircraft alloy when checked on <a href="http://www.matweb.com/" target="_blank">http://www.matweb.com/</a></p><p></p><p>Once annealed my blades straightened frighteningly easily under a fly press and the spindle holes were checked against a known, straight set. Some form of crack testing should be performed after re-hardening, especially if the bend was severe. We used penetrant dye (because we had some) but you could use ultrasonic or x-ray.</p><p></p><p>When given the chemical composition of the alloy the heat treatment works were able to look up the required treatment specifications.</p><p></p><p>All of this worked for me and has been ok for 15,000 miles - Try it yourself at your peril. </p><p></p><p>AL - Base</p><p>Cr <0.01%</p><p>Cu 2.25%</p><p>Fe 1.02%</p><p>Mg 0.67%</p><p>Mn 0.10%</p><p>Ni 1.21%</p><p>P <0.005%</p><p>Pb 0.02%</p><p>Si 1.03%</p><p>Sn <0.01%</p><p>Ti 0.10%</p><p>Zn 0.06%</p><p></p><p>Vickers hardness test 145 VPN</p></blockquote><p></p>
[QUOTE="Pete Appleton, post: 8654, member: 145"] [b]Facts and figures[/b] Looks as though the old man beat me to this as I have to work for a living and he keeps reminding me that he should be retired by now. But here is my contribution:- I recently did a bit of research on this matter as the fork blades that I used in building my Rapide had suffered a fatal encounter with the side of a car, back in the sixties. To start with we tried an odd and severely bent blade that was lying around the shed. When put under the press, with no pre-treatment, it put up a lot of resistance and then broke. Consultation with my friendly, local heat treater produced some suprising information :- Annealing of aluminium alloy is totally the reverse to steel. You take the aluminium up to a temperature, dependant on the chemical composition of the alloy, and then quench it. Salt bath solution is just one type of heat treatment furnace. Mine was done in an air blast furnace with no ill effects. Once annealed the alloy will then begin to re-harden with time. This once again depends on temperature and composition. The higher the temperature the faster the hardening will take place. I was advised to carry out the hardening within a day of the annealing and to keep the blades cool, i.e. not in front of a heater, until we had finished straightening. Re-hardening is known as precipitation hardening or artificial ageing. This involves heating the material to a specific temperature for a time and then allowing it to cool slowly. I sent a piece of the first, broken, blade to 'Bodycote materials testing Teeside' for destructive analysis. The results were as listed at the end of this. This seems to equate to a 2000 series aircraft alloy when checked on [url]http://www.matweb.com/[/url] Once annealed my blades straightened frighteningly easily under a fly press and the spindle holes were checked against a known, straight set. Some form of crack testing should be performed after re-hardening, especially if the bend was severe. We used penetrant dye (because we had some) but you could use ultrasonic or x-ray. When given the chemical composition of the alloy the heat treatment works were able to look up the required treatment specifications. All of this worked for me and has been ok for 15,000 miles - Try it yourself at your peril. AL - Base Cr <0.01% Cu 2.25% Fe 1.02% Mg 0.67% Mn 0.10% Ni 1.21% P <0.005% Pb 0.02% Si 1.03% Sn <0.01% Ti 0.10% Zn 0.06% Vickers hardness test 145 VPN [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
girdraulic blades-straightening
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