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Steel Making

Alloying Elements
Commercial steels of even the simplest types are therefore p...

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

Annealing
ANNEALING can be done by heating to temperatures ranging from...

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

Preventing Cracks In Hardening
The blacksmith in the small shop, where equipment is usually ...

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...

Quenching
It is considered good practice to quench alloy steels from th...

Classifications Of Steel
Among makers and sellers, carbon tool-steels are classed by g...

Heat Treatment Of Punches And Dies Shears Taps Etc
HEATING.--The degree to which tools of the above classes shou...

Machineability
Reheating for machine ability was done at 100 deg. less than ...

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

Hardening
The forgings can be hardened by cooling in still air or quen...

Application To The Automotive Industry
The information given on the various parts of the Liberty eng...

Instructions For Working High-speed Steel
Owing to the wide variations in the composition of high-speed...

Open Hearth Process
The open hearth furnace consists of a big brick room with a l...

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

Double Annealing
Water annealing consists in heating the piece, allowing it to...



Knowing What Takes Place






Category: HARDENING CARBON STEEL FOR TOOLS

How are we to know if we have given a
piece of steel the very best possible treatment?

The best method is by microscopic examination of polished and etched
sections, but this requires a certain expense for laboratory equipment
and upkeep, which may prevent an ordinary commercial plant from
attempting such a refinement. It is highly recommended that any
firm that has any large amount of heat treatment to do, install
such an equipment, which can be purchased for from $250 to $500.
Its intelligent use will save its cost in a very short time.

The other method is by examination of fractures of small test bars.
Steel heated to its correct temperatures will show the finest possible
grain, whereas underheated steel has not had its grain structure
refined sufficiently, and so will not be at its best. On the other
hand, overheated steel will have a coarser structure, depending
on the extent of overheating.

To determine the proper quenching temperature of any particular
grade of steel it is only necessary to heat pieces to various
temperatures not more than 20 deg.C. (36 deg.F.) apart, quench in water,
break them, and examine the fractures. The temperature producing
the finest grain should be used for annealing and hardening.

Similarly, to determine tempering temperatures, several pieces
should be hardened, then tempered to various degrees, and cooled
in air. Samples, say six, reheated to temperatures varying by 100 deg.
from 300 to 800 deg.C. will show a considerable range of properties,
and the drawing temperature of the piece giving the desired results
can be used.

For drawing tempers up to 500 deg.F. oil baths of fresh cotton seed
oil can be safely and satisfactorily used. For higher temperature
a bath of some kind of fused salt is recommended.





Next: Hints For Tool Steel Users

Previous: Temperatures To Use



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