Off topic leaf spring question

[Beile]

I was reading on an RV forum about this but it has no mention of tempering afterwards, wouldn't they break with use, or is not critical with leaf springs? Of course he just might have not noticed the guy tempering them afterwards too, because he does mention the guy does it on all kinds of equipment. I'm not questioning his ability if he does it for a living. Just curious. This was the post:




"Re-arc'ing , these guys put each individual leaf in a furnace and got them white hot - they go flat in that heat. the leaf gets taken out and then bent (it only take slight pressure when white hot) in a form.

Then the guy "shocks" them by hitting them with light hits of a small sledge.

Then while still white / orange hot, the leaf gets put into oil to cool.

then the leaf gets taken out, matched into another form, and the crazy blacksmith beats the ever loving******out of it - every minute or so the leaf gets put into a form to ge checked for shape - this goes on and on until the blacksmith is satisfied.

The process is repeated on the next leaf.

This is a big rig (diesel truck 18 wheeler) spring place, they work on all kinds of rigs, farm equipment, super size loaders, suped up 4x4's, make custom springs for old vintage cars and race cars, etc.

They say that most spring places "roll" the springs to re arc , with a machine - not usually using heat at all .

So this is the type of re arc that doesn't last - because the metal has a shape memory and eventually wants to return to original shape.

Without completely restructuring the molecules by super long and hot heat, shaping, shocking, and then beating the******out of them, thats what happens.

And this old time blacksmith work is very hard, time consuming, dangerous, and precise.
(according to the old blacksmith - he was about 67, the guy who did all the work - you wouldnt believe how hard he was hitting the leafs !"

 

[Nathan the Machinist]

They should not be taken to white heat - that is way too hot for that, they would need tempering after quench, I'm not sure what all the hammering is about, and steel holds together with metallic bonds, not molecular bonds.

I would think the best way to do that would be to heat to a dull red, form to shape, reheat to a bright red, quench - pull from the oil while still quite hot and tweak the final shape as it cools, then temper for an hour twice. But what do I know, I'm not a 67 year old blacksmith.

His way is sure to not bend back - but it may break catastrophically instead

 

[Kevin R. Cashen]

That description makes me feel better about bladesmithing as a whole since it contrasts how much progress we have made in the last 20 years. “white hot”, “shocking” the steel, “restructuring molecules”, “metal memory”, ect… were pretty much the same uneducated concepts bladesmithing used to widely struggle under, and all of it was also automatically gospel if it came from a 67 year old smith. I was never sure if it was the age or the profession that made older smiths, taking wild guesses at explaining the world around them, infallible. But customers gobbled it up and were more than happy to perpetuate the myths, especially if they had bought one of them super duper molecularly restructured blades since $$$$ spent on that knife was also invested in the sales pitch. I have yet to meet the guy excited about telling folks he spent big bucks on a load of hooey.

There is still a lot of work to do but be have come far in bladesmithing, other metal working fields will have to exorcise their own demons.

 

[Bill DeShivs]

I just heat my 1095 to red, quench in canola oil, and temper to just past blue. I have made many hundreds of hard-use springs (auto knife leaf springs) and have never had one fail. One proper heat treat/tempering cycle is all that is needed, if it is done properly.