Development Of Hot-rolled And Ribbed Round Steel Bars 25CrMoA For Ultra-high Strength Oil Sucker

The oil delivery with rod pump is global common mode at present. Oil sucker is one of the most important equipment for rod pump and the super high strenghth oil sucker is most populat oil sucker.In this paper, Hot-rolled and ribbed round steel bars 25CrMoA for super-high strength oil sucker is developed on the basis of compositon design, shape improvement and production process, combined with the user's demand and the pratical production process. Plenty of pratical tests showed that the content of Carbon should be controlled in less than 0.04%; transvers libs are set on two opposite sides. The distance of lib is 900mm～1162mm on the same side and that is 400mm～600mm on the adjacent opposite side. The longitudinal directionent of lib is consistent with that of rolled pieces. The conjoint region of the lib salient and rod body is R0.5～R1.5 arc transition. The design of crescent moon type for transverse rib slot,can stop the longitudinal crack on the surface of transverse rib; the excessive wear of transverse rib can be decreased through the controlling of temperature of final rolling, nipping of guarding and rolling path; the straightening can be reached≤3 mm/m after cooling; the round bars are cut by arc-like shearing machine that will bring good end; at (880±15)℃heat for 30 minutes after the water-cooled, 530℃ 545℃air-cooled heat 40 minutes later, the steel σ_b from 963 MPa 975 MPa,σ_s from 900 MPa 930 MPa,δ₂₀₀ from 9% to 11% ensure the mechanical properties of steel to meet the standards. After the analysis of extensibility after cutting, we think that fixed scale distance does not involve the affection of diameter to the testing result, so, it is a trial for heat treatment within 15℃of tempering range. The pratical application showed that such oil sucker has the advantages of eccentric wear proof and paraffin cutting that can decrease the decrease load of oil pump the breaking accident of pump rod.