Rare earth containing, high-strength and high-toughness seamless steel pipe for L555Q pipeline and production method thereof

A high-strength, high-toughness, seamless steel pipe technology, applied in the field of ferrous metal smelting and metal pressure processing, can solve problems such as unreported

Inactive Publication Date: 2014-02-26
INNER MONGOLIA BAOTOU STEEL UNION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

L555Q is an ultra-high steel grade for pipeline branch lines. L555Q steel grade pipeline pipes have been developed successively at home and abroad. They can all adopt the heat treatment process of quenching + high temperature tempering. After retrieval, the Chi...

Method used

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  • Rare earth containing, high-strength and high-toughness seamless steel pipe for L555Q pipeline and production method thereof
  • Rare earth containing, high-strength and high-toughness seamless steel pipe for L555Q pipeline and production method thereof
  • Rare earth containing, high-strength and high-toughness seamless steel pipe for L555Q pipeline and production method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] Raw materials by weight percentage: 90% blast furnace hot metal, 10% high-quality steel scrap.

[0046] The sequence of the production process is: molten iron pretreatment→top-bottom combined blowing converter smelting→LF furnace refining→VD vacuum treatment→round billet continuous casting→cutting→tube billet heating→piercing→continuous rolling→fixing (stretching and reducing) diameter→cooling→ Sawing → heat treatment → straightening → flaw detection → chamfering.

[0047] The specific production process is briefly described as follows:

[0048] 90 tons of blast furnace molten iron was pretreated with "metal magnesium powder" for desulfurization and deoxidation, so that the S content in the molten iron was reduced to less than (weight percent) 0.010%;

[0049] Mix the 90 tons of pretreated molten iron into a 100-ton top-bottom combined blown converter, add 10 tons of high-quality steel scrap, and then use the single slag process for smelting. The final slag basicity is...

Embodiment 2

[0072] The ratio of raw materials, production process, etc. and other process indicators of Example 2 are the same as those of Example 1, the difference is the chemical composition content, heat treatment system and steel pipe specification of the tube blank (the specification is ф114.3mm×7.90mm) , the chemical composition test results (weight %) are shown in Table 4:

[0073] Table 4 Test results of chemical composition (weight %)

[0074]

[0075] The heat treatment system is: heat preservation at 900±10°C for 35 minutes and then water quenching, and tempering temperature at 610±20°C for 60 minutes and air cooling.

[0076] Steel pipe straightening temperature is 517 ℃.

[0077] The test results of mechanical properties of seamless steel pipes are shown in Table 5.

[0078] Table 5 Test results of mechanical properties of steel pipes

[0079]

[0080] The structure is tempered sorbite, the grain size is grade 9, and the residual stress measured by ring cutting meth...

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Abstract

The invention relates to a rare earth containing, high-strength and high-toughness seamless steel pipe for the L555Q pipeline and a production method thereof. The seamless steel pipe is composed of 90 wt% of blast furnace molten iron and 10 wt% of high-quality waste steel in percentage by weight. The pipe blank comprises the following chemical components in percentage by weight: 0.06 to 0.13 wt% of C, 0.15 to 0.35 wt% of Si, 1.10 to 1.40 wt% of Mn, not more than 0.020 wt% of P, not more than 0.010 wt% of S, 0.10 to 0.30 wt% of Cr, 0.03 to 0.09 wt% of V, 0.01 to 0.03 wt% of Ti, 0.01 to 0.04 wt% of Al, 0.0005 to 0.0100 wt% of rare earth (RE), not more than 0.10 wt% of Cu, and the balance being substrate Fe and undetectable trace impurity elements. The mechanical properties of the seamless steel pipe are as follows: the yield strength is 600 to 680 MPa, the residual stress is smaller than or equal to 30 MPa, the impact value is more than or equal to 160 J/cm<2>, and the grain size is more than or equal to 8.5 grade. The technology process can be simplified as the following steps: molten iron pre-treating, smelting in a top-bottom combined blowing converter, refining in a LE furnace, VD vacuum processing, round continuous casting, cutting, heating the pipe blank, perforating, continuous rolling, sizing (stretch reducing), cooling, sawing, heat treating, straightening, flaw detecting, and chamfering. The product has the advantages of low impurity element content, high roughness matching degree, uniform and fine tissue, and good welding performance.

Description

Technical field: [0001] The invention belongs to the field of ferrous metal smelting and metal pressure processing, and relates to a rare earth-containing high-strength and high-toughness L555Q seamless steel pipe and a production method thereof. Background technique: [0002] Pipeline transportation is widely used because of its cost-effective, uninterrupted and pollution-free characteristics. In order to realize the long-distance transportation of pipelines, high-pressure transportation is used. In order to reduce the cost of laying pipelines and the use of steel materials, high-grade steel is used. Thin-walled pipes adopt low carbon equivalent design components in order to ensure the welding performance of line pipes. Low carbon equivalent and high strength are contradictory. L555Q is an ultra-high steel grade for pipeline branch lines. L555Q steel grade pipeline pipes have been developed at home and abroad, and both can adopt the heat treatment process of quenching + hig...

Claims

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Application Information

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IPC IPC(8): C22C38/28
Inventor 丰小冬刘金贺景春张行刚乔爱云王秀姜海龙石晓霞马爱清
Owner INNER MONGOLIA BAOTOU STEEL UNION
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