How was the L, LT, ST coordinate system for Metals developed and adopted?
I am talking with some colleagues about comparing metallic and non-metallic materials. Obviously, "apples-to-apples" comparisons need to happen and that naturally means you need to equate certain directions in different coordinate systems.
This got me thinking: "how did MMPDS settle on L, LT, ST?" Was there resistance to forgings and extrusions being subjected to the same coordinate system (especially when you are looking at cylindrical vs non-cylindrical forms)? How were arguments against placing these various forms together in a single coordinate system resolved? Is there any documentation about the process that I could access, such as meeting notes?
Materials' properties can vary with direction - this is called anisotropy. Various kinds of materials have "industry standard" coordinate systems so people know which directions people are talking about. For metals within aerospace engineering, this is the Metallic Materials Properties Development and Standardization organization. This group has determined (somehow?) that most directional properties can be described using their coordinate system, the orthogonally placed Longitudinal (or Long), Long Transverse, and Short Transverse directions. This allows for end products of varying metal-forming processes to be compared to each other: extruded vs cast vs forged etc. This sometimes, but not always, corresponds to grain directions. These grain directions, otherwise known as crystal orientations, are important to the materials behavior.