Take Time For Hardening

: The Working Of Steel

Uneven heating and poor quenching has

caused loss of many very valuable dies, and it certainly seems

that when a firm spends from $75 to $450 in cutting a die that

a few hours could be spared for proper hardening. But the usual

feeling is that a tool must be hurried as soon as the hardener

gets it, and if a burst die is the result from either uneven or

overheated steel and quenching same without judgment, the steel
gets the blame.

Give the steel a chance to heat properly, mix a little common sense

with your 30 years experience on the other fellows steel. Remember

that high-carbon steel hardens at a lower heat than low-carbon

steel, and quench when at the right heat in the two above ways,

and 99 per cent of the trouble will vanish.

When a die flies to pieces in quenching, don't rush to the

superintendent with a poor-steel story, but find out first why it

broke so that the salesman who sold it will not be able to harden

piece after piece from the same bar satisfactorily. If you find

a cold short, commonly called a pipe, you can lay the blame

on the steelmaker. If it is a case of overheating and quenching

when too hot, you will find a coarse grain with many bright spots

like crystals to the hardening depth. If uneven heating is the

cause, you will find a wider margin of hardening depth on one side

than on the other, or find the coarse grain from over-heating on

one side while on the other you will find a close grain, which

may be just right. If you find any other faults than a pipe,

or are not able to harden deep enough, then take the blame like

a man and send for information. The different steel salesmen are

good fellows and most of them know a thing or two about their own


For much work a cooling bath at from 50 to 75 deg.F. is very good both

for small hobs, dies, cutter plates or plungers. Some work will

harden best in a barrel of brine, but in running cold water, splendid

results will be obtained. Cutter plates should always be dipped

corner first and if any have stripper holes, they should first

be plugged with asbestos or fire clay cement.

In general it may be said that the best hardening temperature for

carbon steel is the lowest temperature at which it will harden