API Class SM sucker rod coupling 1)Material: Seamless Alloy Steel 40Cr (AISI 5140) 2)Standard: API Spec 11B 3)Size: 5/8¿ò; 3/4¿ò; 7/8¿ò; 1¿ò; 1-1/8¿ò 4)Type: Full size and Slim Hole 5)Smoothness: 3.1í-10-3 6)Coat Thickness(in): 0.01in ~ 0.02in 7)Basic hardness: HRC 16-23 8)Surface Hardness: HRA 58-62 9)Intergrate intension(Mpa): 484 10)Hole rate: 180 days.
