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Cast iron Bird repair

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  • Cast iron Bird repair

    The joint between the reinforcement rod legs of the bird and the cast iron body cracked.

    Cast iron is a little tricky to weld. Besides the fact that some alloys are not weldable, all cast iron is very weak in tension, which can result in cracking when the weld cools off and shrinks. Normally the best technique is to preheat the entire casting to a temperature of 1200°F Then weld it. Then let it cool slowly. A critical temperature in most cast iron is about 1450 degrees F. When at this temperature, conditions that can lead to cracking occur. While the arc will heat the casting to temperatures above this level, it is important that the casting not be held at this temperature for long periods of time. In the case of this bird I didn’t want to preheat above 250 degrees F, because I was worried that the preheat would damage the paint. I selected a Nickel-Chromium-Molybdenum super alloy aerospace rod called Hastelloy W. It contains 55% Nickel, which can absorb a whole bunch of carbon and iron and still remain ductile. It has a tensile strength of 110 KSI and an elongation of 42%. Below is a table comparing Tensile Strength and elongation for various alloys

    1. Tensile Strength Table

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    Below are some pictures of the weld and the whole bird.
    Sorry, but I didn't take a picture of the original crack.

    2. Whole repaired Bird

    Click image for larger version

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    3. Weld with leg and body
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    4. Close up of weld
    Click image for larger version

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    -Don

    Attached Files
    Miller Thunderbolt
    Smith Oxyacetylene Torch
    Miller Dynasty 200DX
    Lincoln SP-250 MIG Welder
    Lincoln LE 31 MP
    Lincoln 210 MP
    Clausing/Colchester 15" Lathe
    16" DuAll Saw
    15" Drill Press
    7" x 9" Swivel Head Horizontal Band Saw
    20 Ton Arbor Press
    Bridgeport
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