Gilbert R. Speich's "The Growth of Bainite," tells a riveting story of ingenuity, discovery, and the relentless pursuit of knowledge.
Bainite was discovered in 1930, a strange hybrid, exhibiting characteristics of two other well-known steel structures, martensite and pearlite. This made it a source of intense scientific curiosity. Speich's work was a direct, audacious attempt to watch this transformation happen in real time.
To study the microscopic, high-speed transformation of steel into bainite, Speich and his team built their own instrument where a tiny, polished steel sample sat on a miniature stage, heated to glowing temperatures by what the thesis specifies as "six feet of 0.020 inch platinum wire wound in the form of a tight helix." Oxidation was avoided by evacuating the active chamber that had a clear quartz window, allowed Speich to peer inside and photograph the process. The cooling from red heat was controlled using a helium blast. This was in the 1950s, long before the age of digital controls. The experiment required immense skill and relied on the displacements caused by bainite to reveal its presence.
One of the findings was that individual sheaves of bainite grew at a constant rate. As his plots clearly show, the growth lines were straight.
It was the harbinger of many subsequent mathematical models purporting to explain the observations.
The thesis systematically demonstrated that increasing the carbon content in the iron-carbon alloys "markedly lowered" the growth rates of bainite sheaves. He also found that adding small amounts of common alloying elements like chromium and nickel significantly decreased the growth rate, even when the carbon level was held constant.
Speich went further, proposing a "Modified Fisher growth model" to better account for the "surface upheavals" he directly observed. Using the power of the electron microscope,he found no evidence for the precipitation of carbide within the austenite," resolving a long-standing discussion.
Speich's thesis shows the full arc of discovery: from the raw ingenuity of building a custom "time machine" for steel, to revealing a simple physical law, applying it to real-world alloys, and ultimately providing the hard evidence that defined scientific debate.