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34CrMo round pipe steel billet with diameter of 350 mm and making and casting process thereof

A technology for round tubes and billets, which is applied in the field of 34CrMo round tube billets and smelting and casting technology to achieve the effects of avoiding brittle fracture, improving the uniformity of solidification structure, and improving usability

Active Publication Date: 2016-06-22
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 center segregation to improve the composition uniformity of the slab and the specific methods of controlling other internal quality indicators of the slab have not been involved.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] 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%-0.09%, the end point phosphorus is 0.008%, the end point temperature is controlled at 1671-1676°C, and the ladle slag thickness is controlled at 68-80mm.

[0037] 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 0.045% to 0.050%. , after LF treatment, the fixed temperature is 1611-1620°C, LF outbound [S] is 0.005%-0.007%, [S]+[P] is 0.018%-0.020%.

[0038] After the molten steel arrives at the station, the RH refining argon blowing flow rate is controlled at 1100NL / min, the treatment time is 11-13.5 minutes when the vacuum degree is less than 3mbar, and t...

Embodiment 2

[0042] 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% to 0.10%, the end point phosphorus is 0.008% to 0.010%, the end point temperature is controlled at 1679~1690°C, and the ladle slag thickness is controlled at 62~77mm.

[0043] 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% to 0.049%. , after the LF treatment, the fixed temperature is 1609-1613°C, the outbound [S] of LF is 0.006%-0.008%, and the [S]+[P] is 0.017%-0.020%.

[0044] After the molten steel arrives at the station, the RH refining argon blowing argon flow rate is controlled at 1400NL / min, the processing time is 10-11.5min when the vacuu...

Embodiment 3

[0048]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.

[0049] 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%.

[0050] 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 34CrMo round pipe steel billet with the diameter of 350 mm and a making and casting process thereof, belongs to the technical field of steel pipe making and rolling, and provides a 34CrMo round pipe steel billet which is reasonable in content of alloy components and structural distribution of internal crystal images and high in structural quality, and a making and casting process thereof. The 34CrMo round pipe steel billet is prepared from C, Si, Mn, P, S, Cr, Mo, Cu, Ni and the balance of Nb, Ti, B, V, Zr, As, Sn, Pb, Sb, Bi and Fe, wherein the central segregation rate, the section porosity and the length of an equiaxed crystal zone of an ingot of the 34CrMo round pipe steel billet finished product are properly optimized. The making and casting process comprises the steps of smelting in a converter, refining in an LF, RH refining and continuous casting of the 34CrMo round pipe steel billet with a section of [phi] 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 invention also relates to a refining and casting process for the 34CrMo round tube billet. 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 stress is much lower than its own yi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/18C22C38/12C22C38/16C22C38/14C22C38/04C22C38/02B22D11/00B22D11/16
CPCB22D11/006B22D11/16C22C38/002C22C38/008C22C38/02C22C38/04C22C38/12C22C38/14C22C38/16C22C38/18C22C38/32
Inventor 李红光陈亮陈天明郭华李扬洲郭奠荣杨文中李志强冯远超
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP