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Genuine Toyo CVs - how much would you pay?

John
Steel is funny stuff, if you deform it a bit - not too much - it
actually gets stronger, a process called "work hardening" that changes
its micro-crystalline structure. Over-do it and it breaks.
So forging, which "works" the steel, does actually make it stronger. I
don't know if you've ever heard of Damascus sword blades, which were the
best in their day, but the sword-smiths made them by hammering the steel
flat, turning it over, hammering it flat, and so on. This hardened the
blades making them cut better. Samurai sword blades were made the same
way.
We've also mentioned "case hardening" in this thread. This is a process
that makes the surface of the steel harder by diffusing extra carbon
into it. However hardness is achieved at the expense of some extra
brittleness, so a case-hardened CV joint may last longer than its
slightly more ductile cousin, but when it finally fails this may be a
sudden fracture - as you have found - rather than slight deformation
leading to the clonk-clonk-clonk we know and love.
As for the material itself: there are 10s of thousands of different
steels to choose from, each with slightly different chemical
compositions and/or manufacturing processes. You can buy steel that is
both strong and ductile (typically it has Nickel, Chrome, Molybdenum and
Vanadium added) but this is expensive and would be reserved for very
high value components: I have only come across it once at work, and that
was for the oil "riser" from the seabed to a floating oil-rig.
Here endeth the lesson - I hope it was enlightening!
CB
| Hi Malcolm
| Thanks for the insight, as you know I dont have any practical
knowledge but
| that doesn't stop the questions from lodging in my head.
| So forged is better than casting (why), is the same compisit of metal
not
| used in both cases.
| In that case is the cone made seperate to the shaft.
| cheers
| john 92HDJ 80 1HDT
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Ah Christopher as usual a pleasure to read technical stuff in such a clear
and understandable manner.
Many thanks
John 92HDJ 80 1HDT
SNIP
John
Steel is funny stuff, if you deform it a bit - not too much - it
actually gets stronger, a process called "work hardening" that changes
its micro-crystalline structure. Over-do it and it breaks.
So forging, which "works" the steel, does actually make it stronger. I
don't know if you've ever heard of Damascus sword blades, which were the
best in their day, but the sword-smiths made them by hammering the steel
flat, turning it over, hammering it flat, and so on. This hardened the
blades making them cut better. Samurai sword blades were made the same
way.
We've also mentioned "case hardening" in this thread. This is a process
that makes the surface of the steel harder by diffusing extra carbon
into it. However hardness is achieved at the expense of some extra
brittleness, so a case-hardened CV joint may last longer than its
slightly more ductile cousin, but when it finally fails this may be a
sudden fracture - as you have found - rather than slight deformation
leading to the clonk-clonk-clonk we know and love.
As for the material itself: there are 10s of thousands of different
steels to choose from, each with slightly different chemical
compositions and/or manufacturing processes. You can buy steel that is
both strong and ductile (typically it has Nickel, Chrome, Molybdenum and
Vanadium added) but this is expensive and would be reserved for very
high value components: I have only come across it once at work, and that
was for the oil "riser" from the seabed to a floating oil-rig.
Here endeth the lesson - I hope it was enlightening!
CB
 
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