what is meant by "atmosphere" when referring to heat treating (metals)?

Hi dwe...

the first link I pulled up, had these definitions:
[ http://216.239.51.100/search?q=cache:9lmo75dS750C:www.sfsa.org/sfsa/glossary/deftrmaa.html+%22atmosphere%22+when+referring+to+%22heat+treating%22+metals&hl=en&ie=UTF-8
]

Atmosphere, Furnace
Gases with which metal is in contact during melting or heat
treating.
-----------------------------------------------------------
Atmosphere, Neutral
Furnace atmosphere which is neither oxidizing nor reducing
can be made up of an inert gas e.g. argon, or the products
of combustion.
-----------------------------------------------------------Atmosphere,
Oxidizing
Furnace atmosphere which gives off oxygen under certain
conditions or where there is an excess of oxygen in the
product of combustion, or the products of combustion are
oxidizing to the metal being heated.
-----------------------------------------------------------
Atmosphere, Reducing
Furnace atmosphere which absorbs oxygen under suitable
conditions or in which there is insufficient air to
completely burn the fuel, or the product of combustion is
reducing to the metal being heated.

I guess you can take your pick from those.




Here is an interesting article that mentions
Hydrogen buildup on metal, and the embrittlement
that will result from it.
[ http://216.239.51.100/search?q=cache:lhRMrtq-FZcC:www.lgsea.com/pdf/560-b5.pdf+%22atmosphere%22+when+referring+to+%22heat+treating%22+metals&hl=en&ie=UTF-8
]
(I left it as a cached copy so the words are highlighted)



Another reference, this time to carbonnitriding:
[ Carbonitriding
A process of case hardening a ferrous material in a gaseous
atmosphere containing both carbon and nitrogen. ]

Carbonitriding
A process of case hardening a ferrous material in a gaseous
atmosphere containing both carbon and nitrogen.

Case
The surface layer of an alloy that has been made
substantially harder than the interior by some form of
hardening operation.

Case Hardening
A heat treatment or combination of processes in which the
surface layer of a ferrous alloy is made substantially
harder than the interior. Carburizing, cyaniding,
nitriding, and heating and quenching techniques are
commonly used. Case hardening can provide a hard,
wear-resistant surface on a forging, while retaining a
softer, tougher core.




This is a pretty nice, handy reference page:
[ http://www.principalmetals.com/specifications/step1.asp ]


They refer to atmosphere as this:
[ http://www.principalmetals.com/glossary/result.asp?Tokens=atmosphere
]
CONTROLLED ATMOSPHERE FURNACES 
A furnace used for bright annealing into which specially
prepared gases are introduced for the purpose of maintaining
a neutral atmosphere so that no oxidizing reaction between
metal and atmosphere takes place.




It appears in the heat treating of metals the atmosphere
is the lack of any gasses (No Atmosphere), the controlled
release of gasses (Controlled Atmosphere), and the use
of no controlled gasses (Normal Atmosphere).


- search technique -
"atmosphere" "heat treating" metals
[ ://www.google.com/search?num=20&hl=en&lr=&ie=ISO-8859-1&safe=off&q=%22atmosphere%22+%22heat+treating%22+metals
]

"atmosphere" when referring to "heat treating" metals
[ ://www.google.com/search?num=20&hl=en&lr=&ie=ISO-8859-1&safe=off&q=%22atmosphere%22+when+referring+to+%22heat+treating%22+metals
]



hope this helps, if you have any questions,
just request a clarification



-AI

outstanding