rdening is toward the following:

_First_, slowly and carefully preheat the tool to a temperature
of approximately 1,500 deg.F., taking care to prevent the formation
of excessive scale.

_Second_, transfer to a furnace, the temperature of which is
approximately 2,250 to 2,400 deg.F., and allow to remain in the furnace
until the tool is heated uniformly to the above temperature.

_Third_, cool rapidly _in oil_, dry air blast, or lead bath.

_Fourth_, draw back to a temperature to meet the physical requirements
of the tool, and allow to cool in air.

It was not very long ago that the desirability of drawing hardened
high-speed steel to a temperature of 1,100 deg. was pointed out, and it
is indeed encouraging to learn that comparatively few treaters have
failed to make use of this fact. Many treaters at first contended
that the steel would be soft after drawing to this temperature and
it is only recently, since numerous actual tests have demonstrated
its value, that the old prejudice has been eliminated.

High-speed steel should be delivered only in the annealed condition
because annealing relieves the internal strains inevitable in the
manufacture and puts it in vastly improved physical condition. The
manufacturer's inspection after annealing also discloses defects
not visible in the unannealed state.

The only true test for a brand of high-speed steel is the service that
it gives by continued performance month in and month out under actual
shop conditions. The average buyer is not justified in conducting a
test, but can well continue to purchase his requirements from a
reputable manufacturer of a brand that is nationally known. The
manufacturer is always willing to cooperate with the trade in the
conducting of a test and is much interested in the information
received from a well conducted test. A test, to be valuable, should be
conducted in a manner as nearly approaching actual working conditions
in the plant in which the test is made as is practical. In conducting
a test a few reputable brands should be allowed to enter. All tools
entered should be of exactly the same size and shape. There is much
difference of opinion as to the best practical method of conducting
a test, and the decision as to how the test should be conducted
should be left to the customer, who should cooperate with the
manufacturers in devising a test which would give the best basis
for conclusions as to how the particular brands would perform