[Antennas] Penetrox, Noalox, Alumatrox

2002年8月30日 18:13:29 -0400

All steels are carbon. Some of them so called low carbon or high carbon 
steels. If steel contain alloying elements (Chromium or Nickel) in low 
percentages such as around perhaps 1 to 4% is then called low alloy 
steel. If content of chromium approaches 16 to 18% is then called 
stainless 
steel. Good (By saying good I mean good rusting resistance properties) 
stainless steel contain about 18 to 20% chromium. 
As far as chromalloy (4130 or SAE4130 - AMS6374B) mast is concerned it 
is low alloy steel. It contain .80 to 1.10 Chromium and .15 to .25% 
Molybdenum. Now you know the name of it - Chromoly 4130. Tensile 
strength of it is minimum 95 Ksi versus around 50 to 80 Ksi for carbon 
steel. 
Stainless steel for marine environment: 
I quote from Metals Handbook. 
In 1953, Subcommittee IV of ASTM Committee A-10 started a series of test 
exposures of 2 ft-sq panels of chromium, chromium - nickel, and chromium- 
manganese-nickel stainless steel at Pittsburgh and on the roof of the New 
York Port Authority Building. In 1956 the letter samples were transferred 
to the ASTM test site at Newark, NJ. Inspection of panels in 1957 showed 
the following results.
At Newark, NJ.
410 - A few rust specks on skyward surface and many pits visible at 40x. 
Heavy rust on ground ward surface. 
430 - No rust on skyward surface. Slight rusting on ground ward surface. 
442, 446, 301, 304, 201 - No rust on skyward surface or ground ward 
surface.
At Pittsburgh
410 - Many minute pits and a few scattered rust specks on skyward 
surface. Scattered rust areas on ground ward surface, but less than at 
Newark.
430, 442, 446, 301, 304, 201 - No rust on skyward surface or ground ward 
surface.
Sorry for a lengthy posting.
Andy - VA3PL