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Old 05-02-12, 11:04 AM   #1
calstar 
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Lotus mangalloy characteristics

I picked up a pretty beat up Lotus Eclair frame, Mangaloy(as spelled on the decal) tubing. When adding braze-ons, etc. are there any different methods/materials needed as compared to cromo, or is it pretty much the same? I've read that mangalloy work hardens so it may be difficult to drill, but maybe thats when working with mang plate and not thin tubes.

thanks, Brian

the following is from the wiki on mangalloy:

Mangalloy is made by alloying steel, containing 0.8 to 1.25% carbon, with 11 to 15% manganese.[1] Mangalloy is a unique non-magnetic steel with extreme anti-wear properties. The material is very resistant to abrasion and will achieve up to three times its surface hardness during conditions of impact, without any increase in brittleness which is usually associated with hardness.[2] This allows mangalloy to retain its toughness.

Most steels contain 0.15 to 0.8% manganese. High strength alloys often contain 1 to 1.8% manganese.[3] At about 1.5% manganese content, the steel becomes brittle, and this trait increases until about 4 to 5% manganese content is reached. At this point, the steel will pulverize at the strike of a hammer. Further increase in the manganese content will increase both hardness and ductility. At around 10% manganese content the steel will remain in its austenite* form at room temperature.[4] Both hardness and ductility reach their highest points around 12%, depending on other alloying agents.[1]


I didn't have a clue what austenite was, maybe you don't either, so here is the def (I also don't get some this definition, but I don't want to turn the thread into a dictionary/theasuarus/technical abstract so thats it for me!).

Noun 1. austenite - a solid solution of ferric carbide or carbon in iron; cools to form pearlite or martensite
gamma iron - a nonmagnetic allotrope of iron that is the basis of austenite; stable between 906 and 1403 degrees centigrade
austenitic steel - steel that has enough nickel and chromium or manganese to retain austenite at atmospheric temperatures
primary solid solution, solid solution - a homogeneous solid that can exist over a range of component chemicals; a constituent of alloys that is formed when atoms of an element are incorporated into the crystals of a metal
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Old 05-02-12, 12:33 PM   #2
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I have never heard of that stuff. Hard to drill materials often work OK if the bit is sharp, and you use a low speed high pressure drill press and lubricate. If you don't have a drill press, a drill driver set on screw, and pushed hard with a center drill is often pretty effective. And better still a brace that will take a center bit. The overall objective being that as the drill turns a shaving is being formed. That way there is little opportunity to harden the metal. A carbide drill is another option, but I have mostly gotten by without those.

As far as how to attach the BOs, what can you tell from the ones already on there?
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Old 05-02-12, 01:02 PM   #3
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Originally Posted by MassiveD View Post

As far as how to attach the BOs, what can you tell from the ones already on there?
Looks like your typical BOs. Probably no big deal, just asking because I've never worked with mangalloy.

Brian
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Old 05-02-12, 01:02 PM   #4
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since most of those stickers were designed by the marketing department, it's probable that it was manganese molybdenum like Reynolds 531. In other words it's not a particularly exotic steel and silver will work fine for braze ons. Just to be clear, silver works on any steel used in bike construction that I am familiar with.
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Old 05-02-12, 07:06 PM   #5
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I sold many Lotuses (Loti?) BITD. The steel seemed to be pretty typical stuff. The one I had to drill into was no different then other frame alloys. Never touched a torch but don't think that would be any different either. We viewed the lable as a marketing thing. Trying to be attractive but not having to pay out to the big tubing suppliers. Andy.
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Old 05-02-12, 07:57 PM   #6
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thanks for the info. Brian
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Old 05-02-12, 11:29 PM   #7
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It's really easy to tell if it's proper austenitic Mangalloy. Austenites have a Curie point below room temperature so they are effectively non-magnetic.

If it's an ordinary steel with moderate manganese it will be ferritic and thus strongly magnetic.I'm betting it's this last.
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