 冷軋
 cold rolled
 光亮退火
 Bright annealed
 內壁粗超度均勻,粗糙度在0.45um
左右
 Uniform wall roughness,roughness
around the 0.45um
 英制國標規格居多,公差范圍小,
內外表面干凈
 British and national standard
specification,tight tolerances,inside
and outside surfaces cleanin