... , including Spray Metal coupling, class T coupling, Altra High Strength,Sub OD coupling, with various spec. of Full size, ... in China. PRODUCT BRIEF: Ultra High Strength sucker rod coupling for use with high strength sucker rods, adopts high stregnth alloy ... (%)Reduction of crosssection area, (%)Ballistic Work Akv(J)Notched bar impact strength , kv (J/cm2)HardnessBlank sample sizeAISI 4140 ≥980(100)≥ ...