Heat and Strength of homemade anchor.

[svsavannah]

Hi there, No experience with this so i thought i would ask ;-)

I made an anchor out of mostly 20 and 16mm plate salvaged from an excavator arm and bucket. I did a whole lot of welding on it and it obviously got hot. Not sure how hot. but i worked into the night and as it got darker i noticed a dull red glow.... it was too hot to touch, so i went to bed.

Simple question:

What has happen to the strength of the anchor? should I have dunked it in water or oil or something? The anchor is for a 8 ton sail boat and is way bigger than it needs to be, I don't imagine the steel will ever yield in normal use, but in the event of a cyclone or tsunami or something crazy it would be good to have maximum strength- or just feel like I at least have done what any iron age peasant would know to do.

[big-all]

in general even if an anchor is "soft" it will still be fully as strong it will just wear a bit quicker as its strong enough but soft
this assumes you mean a boat type anchor and not an anchor point reliant on full steel strength

[dewaltdisney]

If I can remember from metal work at school, rapid quenching or slow cooling can both cause issues in hardness and brittleness due to the crystalline structure of the metal changing. I cannot remember which does what but I am thinking that the heat from welding was probably not enough to affect the metallurgic structure of the anchor.

DWD

[big-all]

isnt it quench in oils to harden from yellow hot then heat to cherry red and slow cool down to to relieve stress
or am i getting my iceland rocket lollie colours confused
https://www.iceland.co.uk/p/iceland-8-r ... 67047.html

[Chippo1]

It will depend on the steel and it’s composition as to wether it will be affected by the heat you subjected it to.

If ordinary mild steel it will have little of no effect, the steel will remain ductile easily deformed ( that’s relative of course)

If it was a high carbon steel it is more likely to be affected structurally asa result of heat. Getting it red hot and rapidly quenching in water would harden the material , to rapid quenching is likely to result in cracks , hence quenching is done in an oil bath , years ago using whale oil . Other forms of quenching have been used , air blast , sand ect all to avoid cracking. Other stuff in the mix will have serious effects on the process , manganese , chrome , molybdenum ect.

After the quench process you would, land up with a very hard brittle steel, to use the steel say for chisels , tools , springs and other high strength uses you then go on to anneal the steel. This requires the steel to be further heated to a specific temperature for the required ductile strength versus hardness. In a workshop this can be achieved by bright polishing the component , slowly heating and watching the colour changes on the polished steel , light straw through to dark blue.

What sort of anchor have you made, claw , Danforth or such like , boat I sail on displaces 9.5 tonnes and the two anchors we use are surprisingly small to hold in mud and sand , the weight and length of chain is more important than the anchor itself.

[svsavannah]

Thank you Chippo1,
I think it is mild steel, and if the heat is not an automatic huge compromise to its strength i an not worried.

The anchor is oversized for sure, but as a full time cruising boat you always want more chain, and a bigger anchor so you can get a good sleep in a place your not familiar with.

[Chippo1]

Yes for sure you don’t want to find your self wandering along on the tide.

The boat I sail on has a huge amount of chain in the locker , we always put out 5 times depth of water at least so a long piece of chain sits on the bottom doing most of the work.

That’s basically a Danforth isn’t it , are you having it galvanised ?

Forgot to say that steel u used is most likely a fairly high strength high tensile steel so pretty much perfect for that sort of fabrication.

[Hitch]

If its just S275 or S355 mild steel, you dont want to quench it at all. Let it cool naturally.


Depends which bits of the bucket you've used, and even what sort of bucket it was, chance there could be something like a bit of wear plate Raex/Hardox in there.... even then dont quench, it can cause cracking if done wrong.

Quenching is only realy suitable for certain types or steel, such as EN24, where it is heated and quenched to harden.