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

A billet and round tube technology, which is applied in the field of smelting and casting of 34CrMo round tube billets and 34CrMo round tube billets to avoid brittle fracture, improve uniformity and improve usability.

Active Publication Date: 2017-10-27
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 production of large-scale 34CrMo round tube blanks with a φ350mm section, the specific methods for controlling the equiaxed crystal ratio and improving the uniformity and compactness of the solidified structure of the slab have 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 0.10%, 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.

[0044] 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%.

[0045] 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 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 0.06%, 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.

[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 0.043%. 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%.

[0051] 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...

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Abstract

The invention discloses a 350mm-diameter 34CrMo circular tube steel blank and a smelting and casting 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 higher equiaxed crystal rate content in the interior crystal phase structure, and a smelting and casting method of the circular tube steel blank. The 34CrMo circular tube steel blank comprises the following heavy components: 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 length ratio of the zone of equiaxed crystals of the finished product 34CrMo circular tube steel blank is 50.0-52.3%. The smelting and casting 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 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 and casting method for manufacturing the 34CrMo round tube billet with a diameter of 350 mm. 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 suddenl...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/18C22C38/12C22C38/04C22C38/02C22C33/04C21C7/10B22D11/115
CPCB22D11/115C21C7/10C22C33/04C22C38/02C22C38/04C22C38/12C22C38/18
Inventor 李红光陈天明郭华陈亮李扬洲郭奠荣杨文中李志强冯远超
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP