 冷轧
 cold rolled
 光亮退火
 Bright annealed
 内壁粗超度均匀,粗糙度在0.45um
左右
 Uniform wall roughness,roughness
around the 0.45um
 英制国标规格居多,公差范围小,
内外表面干净
 British and national standard
specification,tight tolerances,inside
and outside surfaces cleanin