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34crmo round pipe billet with a diameter of 350㎜ and its refining method

A round tube and billet technology, which is used in the manufacture of converters and the improvement of process efficiency to achieve the effects of improving the uniformity of the solidified structure, improving the usability and avoiding brittle fracture

Active Publication Date: 2018-03-16
PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, for the control of looseness in the center of the larger size 34CrMo round tube billet produced with a φ350mm section, the specific method of improving the density of the central area of ​​the billet has not been involved.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] A steelmaking plant adopts 120t converter smelting → LF furnace refining → RH refining → four-machine four-strand casting machine φ350mm section continuous casting to produce 34CrMo round tube billet. At the end of converter blowing, the end point carbon is controlled at 0.08%, the end point phosphorus is 0.008%, the end point temperature is controlled at 1670°C, and the ladle slag thickness is controlled at 71mm.

[0038] When the molten steel arrives at the LF refining furnace, the molten steel fluctuates slightly for argon blowing, and there is no major overturning phenomenon. The outbound Als is controlled at 0.040%. , the fixed temperature is 1600℃, LF outbound [S] is 0.005%, [S]+[P] is 0.017%.

[0039] After the molten steel arrives at the station, the RH refining argon blowing flow rate is controlled at 1235NL / min, the treatment time is 12 minutes when the vacuum degree is less than 3mbar, and the argon blowing is 7 minutes after the vacuum treatment is completed...

Embodiment 2

[0043] A steelmaking plant adopts 120t converter smelting → LF furnace refining → RH refining → four-machine four-strand casting machine φ350mm section continuous casting to produce 34CrMo round tube billet. At the end of converter blowing, the end point carbon is controlled at 0.06%, the end point phosphorus is 0.010%, the end point temperature is controlled at 1690°C, and the ladle slag thickness is controlled at 62mm.

[0044] When the molten steel arrives at the LF refining furnace, the molten steel fluctuates slightly for argon blowing, and there is no major overturning phenomenon. The outbound Als is controlled at 0.043%. After the refining is completed, the molten steel is softly blown with argon. Afterwards, the fixed temperature is 1613°C, the outbound [S] of LF is 0.006%, and [S]+[P] is 0.015%.

[0045] After the molten steel arrives at the station, the RH refining argon blowing flow rate is controlled at 1400NL / min, the treatment time is 11.6min when the vacuum degr...

Embodiment 3

[0049] A steelmaking plant adopts 120t converter smelting → LF furnace refining → RH refining → four-machine four-strand casting machine φ350mm section continuous casting to produce 34CrMo round tube billet. At the end of converter blowing, the end point carbon is controlled at 0.10%, the end point phosphorus is 0.007%, the end point temperature is controlled at 1674°C, and the ladle slag thickness is controlled at 80mm.

[0050] When the molten steel arrives at the LF refining furnace, the molten steel fluctuates slightly for argon blowing, and there is no overturning phenomenon. The outbound Als is controlled at 0.050%. After the refining is completed, the molten steel is softly blown with argon. Finally, the fixed temperature is 1620°C, the outbound [S] of LF is 0.007%, and [S]+[P] is 0.019%.

[0051] After the molten steel arrives at the station, the RH refining argon blowing flow rate is controlled at 1100NL / min, the treatment time is 11 minutes when the vacuum degree is ...

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Abstract

The invention discloses a 34CrMo round pipe billet with the diameter being 350 mm and a smelting method of the 34CrMo round pipe billet and belongs to the field of steel pipe smelting and rolling. The 34CrMo round pipe billet with the reasonable alloy component content and low in center segregation in an inner crystal structure and the smelting method of the 34CrMo round pipe billet are provided. The 34CrMo round pipe billet comprises C, Si, Mn, P, S, Cr, Mo, Cu, Ni and residual elements of Nb, Ti, B, V+Nb+Ti+B+Zr, As, Sn, As+Sn+Pb+Sb+Bi and Fe, wherein the porosity of the finished 34CrMo round pipe billet ranges from 0.5 level to 1.0 level, the loose region area proportion ranges from 24.8% to 25.0%, and a central zone of metal in situ analysis density ranges from 0.81 to 0.82. The smelting method includes the steps of converter smelting, LF furnace refining, RH refining and continuous casting of the 34CrMo round pipe billet with the diameter phi of the section being 350 mm.

Description

technical field [0001] The invention relates to a 34CrMo round tube billet, in particular to a 350 mm diameter 34CrMo round tube billet, which belongs to the technical field of steel tube smelting and rolling. The present invention also relates to a refining method for manufacturing the 34CrMo round tube billet with a diameter of 350mm. Background technique [0002] 34CrMo tube billet steel is mainly used to produce steel for oil well pipes used in oil and gas exploitation and transportation. The chemical composition of steel grades is as follows: C: 0.31% ~ 0.36%, Si: 0.20% ~ 0.35%, Mn: 0.65% ~ 0.85% %, P≤0.015%, S≤0.010%, Cr: 0.95%~1.15%, Mo: 0.17%~0.24%, Cu≤0.15%, Ni≤0.20%, residual element requirements: Nb≤0.010%, Ti≤0.010 %, B≤0.005%, and V+Nb+Ti+B+Zr≤0.15%; As≤0.015%, Sn≤0.010%, As+Sn+Pb+Sb+Bi≤0.045%, and the balance is Fe. When the product is in use, under the joint action of stress and hydrogen sulfide gas, it will often be brittle and fracture suddenly when the st...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22D11/115B22D11/16C21C5/28C22C38/02C22C38/04C22C38/18C22C38/12C22C38/16C22C38/08C22C38/14
CPCB22D11/115B22D11/16C21C5/28C22C38/002C22C38/008C22C38/02C22C38/04C22C38/08C22C38/12C22C38/14C22C38/16C22C38/18C22C38/32Y02P10/20
Inventor 李红光陈天明郭华李扬洲陈亮郭奠荣杨文中李志强冯远超
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP