It has been suggested that this puzzle was a great favourite among the young apprentices of the City of London in the sixteenth and seventeenth centuries. Readers will have noticed the curious brass grasshopper on the Royal Exchange. This long-lived ... Read more of THE GRASSHOPPER PUZZLE. at Math Puzzle.caInformational Site Network Informational
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Steel Making

Conclusions
Martien was probably never a serious contender for the honor ...

Heavy Forging Practice
In heavy forging practice where the metal is being worked at...

High-chromium Or Rust-proof Steel
High-chromium, or what is called stainless steel containing f...

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

Piston Pin
The piston pin on an aviation engine must possess maximum res...

Placing Of Pyrometers
When installing a pyrometer, care should be taken that it re...

Tungsten
Tungsten, as an alloy in steel, has been known and used for a...

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

Steel Can Be Worked Cold
As noted above, steel can be worked cold, as in the case of ...

Process Of Carburizing
Carburizing imparts a shell of high-carbon content to a low-...

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

Temperature For Annealing
Theoretically, annealing should be accomplished at a tempera...

Silicon
Silicon prevents, to a large extent, defects such as gas bubb...

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

Furnace Data
In order to give definite information concerning furnaces, fu...

Shrinking And Enlarging Work
Steel can be shrunk or enlarged by proper heating and cooling...

Cyanide Bath For Tool Steels
All high-carbon tool steels are heated in a cyanide bath. Wi...

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



Introduction Of Carbon






Category: CASE-HARDENING OR SURFACE-CARBURIZING

The matter to which these notes are primarily directed is the
introduction of carbon into the case of the article to be hardened.
In the first place the chances of success are increased by selecting
as few brands of steel as practicable to cover the requirements of
each component of the mechanism. The hardener is then able to become
accustomed to the characteristics of that particular material, and
after determining the most suitable treatment for it no further
experimenting beyond the usual check-test pieces is necessary.

Although a certain make of material may vary in composition from
time to time the products of a manufacturer of good steel can be
generally relied upon, and it is better to deal directly with him
than with others.

In most cases the case-hardening steels can be chosen from the
following: (1) Case-hardening mild steel of 0.20 per cent carbon;
(2) case-hardening 3-1/2 per cent nickel steel; (3) case-hardening
nickel-chromium steel; (4) case-hardening chromium vanadium. After
having chosen a suitable steel it is best to have the sample analyzed
by reliable chemists and also to have test pieces machined and pulled.

To prepare samples for analysis place a sheet of paper on the table
of a drilling machine, and with a 3/8-in. diameter drill, machine
a few holes about 3/8 in. deep in various parts of the sample bar,
collecting about 3 oz. of fine drillings free from dust. This can be
placed in a bottle and dispatched to the laboratory with instructions
to search for carbon, silicon, manganese, sulphur, phosphorus and
alloys. The results of the different tests should be carefully
tabulated, and as there would most probably be some variation an
average should be made as a fair basis of each element present,
and the following tables may be used with confidence when deciding
if the material is reliable enough to be used.

TABLE 16.--CASE-HARDENING MILD STEEL OF 0.20 PER CENT CARBON

Carbon 0.15 to 0.25 per cent
Silicon Not over 0.20 per cent
Manganese 0.30 to 0.60 per cent
Sulphur Not over 0.04 per cent
Phosphorus Not over 0.04 per cent

A tension test should register at least 60,000 lb. per square inch.

TABLE 17.--CASE-HARDENING 3-1/2 PER CENT NICKEL STEEL

Carbon 0.12 to 0.20 per cent
Manganese 0.65 per cent
Sulphur Not over 0.045 per cent
Phosphorus Not over 0.04 per cent
Nickel 3.25 to 3.75 per cent

TABLE 18.--CASE-HARDENING NICKEL CHROMIUM STEEL

Carbon 0.15 to 0.25 per cent
Manganese 0.50 to 0.80 per cent
Sulphur Not over 0.045 per cent
Phosphorus Not over 0.04 per cent
Nickel 1 to 1.5 per cent
Chromium 0.45 to 0.75 per cent

TABLE 19.--CASE-HARDENING CHROMIUM VANADIUM STEEL

Carbon Not over 0.25 per cent
Manganese 0.50 to 0.85 per cent
Sulphur Not over 0.04 per cent
Phosphorus Not over 0.04 per cent
Chromium 0.80 to 1.10 per cent
Vanadium Not less than 0.15 per cent

Having determined what is required we now proceed to inquire into
the question of carburizing, which is of vital importance.





Next: Using Illuminating Gas

Previous: The Penetration Of Carbon



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