As for your hardening, then annealing, I could be wrong, but
hardening, and tempering are seperate things. Hammers and blunt
chasing tools should be hardened while cutting tools, scribes,
etc. should be tempered.
G’day; Sorry, I can’t agree on this one, I’afraid. If one hardens
a hammer it makes it very brittle, and when used, bits will fly off
at high speed to the detriment of the user. Hammers are often case
hardened; that is, only a depth of about 0.020" of the surface is
hard. Otherwise the whole head is usually furnace tempered. The
usual thing for a hand forged hammer is to temper it back to
plum-to-blue. Cutting tools, including scribers, knives, etc should
be tempered to a light to medium straw colour. Percussion tools,
such as punches, chasing tools, should be tempered to a dark straw.
Screwdrivers, and tools with similar usage should also be dark
straw.
But completely hardened hammers would be dangerous to use. And
whilst we happen to mention danger, note when percussion tools are
well-used, the struck surface usually turns over, like a little
cap. This, because it has been work-hardened is very brittle, and
bits also fly off this at high speed. Take such a tool to the
grindstone and grind off the work-hardened top, which removes the
potential danger. So, to ‘cap’ this homily, do use eye protection
when using percussion tools. –
/\
/ / John Burgess, Nelson, New Zealand
/ /
/ //\ @John_Burgess2
/ / \ \
As for your hardening, then annealing, I could be wrong,
but hardening, and tempering are seperate things. Hammers and
blunt chasing tools should be hardened while cutting tools,
scribes, etc. should be tempered.
Actually an item is usually hardened first. Heated to a
relitively high temp. and quenched in some material (oil, water,
automatic transmission fluid, salt baths of different
concentrations of salt, etc. etc. etc.). There are different metal
alloys that are made to be hardened and tempered in different ways.
For example, there is a product called drill rod (can make drills
out of it) that can be purchased in a relatively soft state. You
can get it in water or oil alloys and when it is time to harden
the item you quench in either water or oil depending on the alloy
type. Once hardened the item needs to be tempered, heated to a
lower temp than to temp to harden the item, but heated to a temp
that will soften the item a bit so it will be hard but not brittle
but is not quenched. This all sounds pretty straight forward, and
is to a certain degree. The alloy used, the temps. used, the time
at the temp, the quench material and its temp and the way the
temper is “drawn” is all in books and charts but what is not there
is the art. There is a great deal of knowledge to do a really
great job of hardening and tempering, but just a little bit of
trial and error can give most folks an ability that will allow them
to do things (make things) they never dreamed of.
My 2 cents worth, hope it helps a bit.
John
John and Cynthia/MidLife Crisis Enterprises
Maiden Metals/C. T. Designs/ Bloomin’ Wax Works. etc.
PO Bx 44, Philo
CA 95466
Ph 707-895-2635 FAX 707-895-9332
The playfulness of the Universe
is reflected in the dance of the stars!
Actually an item is usually hardened first. Heated to a
relitively high temp. and quenched in some material (oil, water,
I’ve made a few gun springs in the past for old pieces that
springs are no longer available for, and you are correct. Hardening
is the process of making the item harder (simple) and tempering is
a kind of stress relief that takes away the brittleness of the
hardening.
With the springs, I used to heat the steel to cherry red and
quench in water. If the spring was then used in this state it would
snap right away. The stress relief or tempering was carried out in a
bath of whale oil (or recently a more friendly, to whales, light
mineral oil). The spring was immersed in the oil and a propane
torch flame was played over the oil. As the oil burned away it
used to control the temperature of the metal so that it tempered
and didn’t anneal again. Another side effect was a slight
case-hardening of the surface of the spring caused by the carbon by
products in the oil.
On a commercial scale steel that needs to be tempered is usually
tempered in an high temperature oven.
I hope this helps.
Regards,
Kerry
Kerry McCandlish Jewellery - Celtic and Scottish styles
Commission/Custom Work undertaken…http://www.bennie.demon.co.uk
Katunayake, Creagorry, Isle of Benbecula, HS7 5PG SCOTLAND
Tel: +44 1870-602-677 Fax: +44 1870-602-956 Mobile: +44 850-059-162