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Phi350mm 34CrMo circular tube steel blank and smelting method thereof

A smelting method and round pipe technology, applied in the field of 34CrMo round pipe billet, 34CrMo round pipe billet and its smelting, and 34CrMo round pipe billet smelting, to avoid brittle fracture, improve solidification structure uniformity, and improve usability

Inactive Publication Date: 2016-05-25
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 center segregation control of larger-sized 34CrMo round tube blanks produced with a φ350mm section, the specific method for improving the composition uniformity of the slab 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 0.09%, the end point phosphorus is 0.008%, the end point temperature is controlled at 1674°C, and the ladle slag thickness is controlled at 80mm.

[0038] 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 0.020%.

[0039] 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 ...

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 0.017%.

[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 11.5min 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 0.08%, 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.

[0050] 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 0.021%.

[0051] 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...

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Abstract

The invention discloses a 350mm-diameter 34CrMo circular tube steel blank and a smelting method thereof, belonging to the technical field of steel tube smelting and rolling. The invention provides a 350mm-diameter 34CrMo circular tube steel blank with reasonable alloy component content and lower central segregation in the interior crystal phase structure, and a smelting method thereof. The 34CrMo circular tube steel blank comprises C, Si, Mn, P, S, Cr, Mo, Cu and Ni. The 34CrMo circular tube steel blank also comprises the following residual elements: Nb, Ti, B, V+Nb+Ti+B+Zr, As, Sn, As+Sn+Pb+Sb+Bi and Fe. The low-power central segregation rate of the finished product 34CrMo circular tube steel blank is Grade 0-0.25, and the spectrum direct-reading segregation degree is 1.03-1.05. The smelting method comprises the following steps: converter smelting, LF (ladle furnace) refining, RH refining, and continuous casting of the 34CrMo circular tube steel blank with the phi350mm cross section.

Description

technical field [0001] The invention relates to a 34CrMo round pipe billet, in particular to a 350 mm diameter 34CrMo round pipe billet and a smelting method thereof, belonging to the technical field of steel pipe smelting and rolling. The present invention also relates to a smelting 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 fra...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/18C22C38/12C22C38/16C22C38/08C21C5/28C21C7/072C21C7/10B22D11/115
CPCC22C38/02B22D11/115C21C5/28C21C7/072C21C7/10C22C38/04C22C38/08C22C38/12C22C38/16C22C38/18
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