The inner pipe wall is case hardened by CNC high-frequency induction hardening machine. The inner pipe wall becomes a wearable layer with high hardness. The concrete pump straight pipe is made of special alloy steel ( 45Mn2). The inner pipe wall is case hardened by CNC high-frequency induction hardening machine. The inner pipe wall becomes a wearable layer with high hardness. The service life of the inner-hardened concrete pump boom pipe is as 3 to 5 times as normal concrete pump pipe.  1. Material: Q235, 20#, 16Mn, ST52, 45Mn2, 37Mn5,