Does ice get colder than 32F/0C? If it does, is it harder then?
What about green wood? There is a lot of water in there.
I don't know the answers to the above questions, maybe someone out there does.
It might help us understand what chopping in cold temperatures does to the axe.
While the bit of an axe is subject to stress from use that is different, or perhaps magnified and subject to be affected more by less, this paper leads me and experience lead me to believe that you have to be pushing 0°f to have the steel of an axe bit be affected in a major way.
As far as "frozen" trees, the Michigan pattern claims its pattern of rounded corners as a direct response to chipping bits in frozen pine. I have no doubt that frozen knots are hell on a bit. There is a diagram, I believe from Kelly axe, that shows what chips are normal and what chips are from a defective temper.
Small dents and chips and dings are quite normal on an axe. And bigger chips, in my experience, are almost always a result of a thin edge. My point in joining in the conversation was not to just call out the person, but to point out the absolute lack of information supporting what temperature is cold enough to require heating up an axe.
In case people do not want to click on a link.
https://www.google.com/url?sa=t&sou...XXatPtOr4xI7Nu1XQ&sig2=o8gOw_cdQSdxnKsIYXMpBA
Quenched and tempered low-alloy steels are, of course, applicable at temperatures
down to -50°F, and many of them.are suitable for use at temperatures down to -lOO°F or
-150°F, but these will be discussed more fully in the next section.
Practically all aluminum and titanium alloys may be used in critically stressed
applications at temperatures down to -SOOF, except for some of the highest-strength
aluminum alloys such as 7178-T6 and 7075-T6. These are not recommended, especially
where sharp changes in section, complex stress distributions or impact loads are in-
volved. Similarly, the all-beta 13V-llCr-3Al-titanium alloy (12OVCA) and the 8 Mn-
titanium alloy tend to be notch-brittle at moderately reduced temperatures.
Nickel and copper-base alloys are virtually all suitable for use at temperatures
down to -50°F, and generally much lower.
Metals for use to -150'F. Low-alloy steels suitable for use at temperatures
down to -150°F fall into two categories: quenched and tempered steels having essen-
tially fine-grained, tempered, martensitic microstructures, and nickel-alloyedcfer-
ritic steels. Most of the lower carbon (0.20 to 0.35% C) low-alloy steels having
sufficient hardenability to achieve martensitic microstructures through the section
thickness when either water- or oil-quenched are, after tempering at appropriate tem-
peratures, sufficiently tough for most critical service applications at temperatures
down to at least -10O0F. Many of these steels contain several alloying elements such
as manganese, nickel,. chromium, molybdenum and vanadium. Several contain small quan-
tities of zirconium or boron, the latter having a potent effect on increasing harden-
ability. These steels include proprietary grades such as T-1 and N-A-XTRA, among
others, as well as standard grades such as 'AMs 6434, 4130, 4335, etc.
Although the above steels are usable to at least -lOO°F, they may, depending
upon steel-making practice, tempering temperature, etc., undergo the tough-to-brittle
transition at some temperature between -lOO°F and -150'F. For more reliable perform-
ance at the lower end of this temperature range, it is necessary to employ somewhat
more highly alloyed quenched and tempered steels such as HY-80 or HY-TUF, both of
which are proprietary steels.
Low-carbon 3yk nickel steel is widely used in large land-based storage tanks to
contain liquefied gases at temperatures down to -150'F. This steel falls under ASTM
A203, Grades D and E, and is subject to impact tests in accordance with. the require-
ments of A-300.
As shown in Fig: 7, a large number of aluminum, nickel, and titanium-base alloys
The high-strength 7079-T6 aluminum alloy may be used down to -200°F, but is
' are suitable for critically stressed applications at temperatures down to -150°F and
lower.
not recommended for lower-temperature applications. In the case of titanium alloys,
the 6A1-6V-2Sn-Ti alloy in the heat-treated condition may be used at temperatures
down to -40°F, and the 16V-2.5Al-Ti alloy may be used down to -lOO°F, but neither is
recommended for use at temperatures lower than these.
- 318 -
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I Metals' for use at -320'F. Increasing the nickel content of low-carbon steel
progressively reduces the temperature of transition from duetile to brittle fracture
as shown in Fig. 3a. In the normalized and tempered condition, a steel with 9% nickel
has a keyhole-notch Charpy impact energy of 30 ft-lb at -320'F. In the quenched and
tempered condition the same steel will show 50 ft-lb impact energy at this temperature.
ASTM A353-58 covers the 9% nickel grade and requires the normalized and tempered heat
treatmqnt. Revision of current pressure-vessel codes to permit quenched and tempered
steel of this grade for pressure vessels will result in improved reliability of low-
temperature storage tanks.
The austenitic stainless steels of the Type 300 series are all suitable for use
at -320°F, as is the heat-treatable A-286 stainless steel. Precipitation-hardenable
stainless steels of the PI3 series are not recommended for subzero temperature applica-
tions since they evidence notch embrittlement at temperatures between OoP and -4OOF.
The recently developed maraging steels of the 20% and 25% nickel varieties, with
various amounts of cobalt, molybdenum, titanium, aluminum and columbium added, exhibit
notch toughness at temperatures down to at least -320°F, and possibly down to liquid-
hydrogen temperature. The maraging steels are readily formable and weldable, and are
hardened by a relatively low-temperature aging at 900°F.
A large number of aluminum alloys, including 2024-T6, 7039-T6, 2014-T6, and
5456-H343 have excellent resistance to brittle fracture at -320°F, although weld joints
in the 20144'6 alloy tend to exhibit brittle behavior at low temperatures.
minum alloys of the 5000 series aluminum-magnesium type are also tough at -320°F and
at. lower temperatures, as are the 6061-T6 and 2219-T87 alloys.
Other alu-
Nickel-base alloys are almost all tough at -320°F, as shown in Fig. 7.
alloys such as the 6A1-4V-Ti (both in the annealed and heat-treated conditions), the
8Al-2Cb-1Ta-TiY and the 5Al-2.5Sn-Ti alloys are ductile and tough at -320°F. It has
been found that impurity elements such as oxygen, nitrogen and carbon, as well as' iron,
can embrittle these alloys at low temperatures; care should be taken to keep these im-
purities as low as possible in materials intended for critical applications at very
low temperatures.
Metals Gorp. of America led to the development of the ELI (extra low impurity) grades
of the 6A1-4V-Ti and 5A1-2.5Sn-Ti alloys.
There is a large gap between the temperature of
Titanium
Cooperative work at General Dynamics/Astronautics and Titanium
Metals for use below -320'F.
liquid nitrogen, -320°F, and that of the next lower-temperature liquefied gas of im-
portance, liquid hydrogen, which boils at -423OF. Liquid helium, boiling at -452'F,
is the only other cryogen that fills this low-temperature range. Liquid hydrogen,
because of the space program, has become of wide commercial significance, and a pro-
duction capacity in the tens of thousands of tons per year has been established here
within the past few years.
Among the steels, only the more highly alloyed austenitic stainless steels are
suitable for use at liquid-hydrogen or helium temperatures. Types 304 and 310 stain-
less steels fall within this classification, and the low-carbon grades of these steels
are recommended, especi.ally when welding is to be perfarmed. There are a number of
low-carbon stainless-steel casting alloys containing generally 18 to 21% chromium and
9 to 14% nickel that may be used for piping, valve bodies, flanges, etc., at -423OF
or lower.
The aluminum alloys that may be safely used at liquid-hydrogen temperatures in-
clude several of the 2000 and 5000 series, as well as the 6061-T6 alloy. Weldments
of the 2219-T87 alloy have demonstrated excellent resistance to brittle fracture at
-423OF, while the lower-strength 5052-H38 and 5083-1138 alloys have also showed good
notch-toughness at: this temperature
I