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A production method for reducing the hardness of x80m grade pipeline steel

A production method and pipeline steel technology, applied in the field of iron and steel metallurgy, can solve problems such as cold-bending cracking, cold cracks, high surface and section hardness values, and achieve the effects of reducing hardness values, improving banded structure, reducing and stabilizing hardness values

Active Publication Date: 2020-07-14
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] X80M grade pipeline steel belongs to high-grade pipeline steel. Due to the addition of more alloys in the smelting process, it is easy to produce a large amount of bainite and a small amount of Maor island in the production process, resulting in surface and cross-sectional hardness of the product. If the value is too high, in the process of pipe making, cold bending cracking is prone to occur after bending, and production problems such as cold cracks are prone to occur after welding and cooling

Method used

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  • A production method for reducing the hardness of x80m grade pipeline steel
  • A production method for reducing the hardness of x80m grade pipeline steel
  • A production method for reducing the hardness of x80m grade pipeline steel

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Comparison scheme
Effect test

Embodiment 1

[0023] The steel plate thickness is 27.2mm, the billet heating temperature is 1229°C, the heating time is 13min / cm, and the soaking time is 42min. Rolling final pass reduction rate 28%, finish rolling temperature 785°C, final rolling temperature 751°C, steel plate theoretical Ar3 temperature 736°C, water entry temperature 715°C, red return temperature 315°C, steel throwing speed after rolling 5.0m / s , the speed of the steel plate entering the water roller table is 0.6m / s, and the acceleration of the roller table is 0.005m / s 2 .

Embodiment 2

[0025] Steel plate thickness 22mm, slab heating temperature 1228 degrees, heating time 13min / cm, soaking time 45min, the first, second, fourth and fifth passes of phosphorus removal in the rough rolling process, the second pass of phosphorus removal in the finish rolling process, rough rolling The reduction rate of the final pass is 28%, the finish rolling temperature is 790 degrees, the final rolling temperature is 757 degrees, the theoretical Ar3 temperature of the steel plate is 747 degrees, the water entry temperature is 719 degrees, the redness temperature is 360 degrees, the steel throwing speed after rolling is 5.0m / s, The speed of the steel plate entering the water roller table is 1.1m / s, and the acceleration of the roller table is 0.010m / s 2 .

Embodiment 3

[0027] The steel plate thickness is 30.8mm, the billet heating temperature is 1210 degrees, the heating time is 13min / cm, and the soaking time is 48min. The reduction rate of the final pass is 26%, the finish rolling temperature is 810°C, the final rolling temperature is 741°C, the theoretical Ar3 temperature of the steel plate is 736°C, the water entry temperature is 712°C, the redness temperature is 453°C, and the steel throwing speed after rolling is 5.0m / s , the speed of the steel plate entering the water roller table is 0.5m / s, and the acceleration of the roller table is 0.003m / s 2 .

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Abstract

The invention discloses a production method for reducing the hardness of X80M-grade pipeline steel. Through a high-temperature rolling process, reasonable adjusting of phosphorus removal process and perfecting of rolling schedule, a laminar flow cooling process is optimized, a hybrid tissue structure is obtained, wherein the edge of the hybrid tissue structure is mainly made of quasi-polygonal ferrite, and the core of the hybrid tissue structure is mainly made of acicular ferrite, bainite and a small amount of martensite and austenite islands, it is ensured that the Wechsler hardness value ofthe surface and the section of a steel plate is stabilized within 220, the performance requirements for the steel plate are ensured, and economic benefits are remarkable.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy, and relates to a production process for effectively reducing the hardness of X80M steel grade pipeline steel by improving a rolling process. Background technique [0002] X80M grade pipeline steel belongs to high-grade pipeline steel. Due to the addition of more alloys in the smelting process, it is easy to produce a large amount of bainite and a small amount of Maor island in the production process, resulting in surface and cross-sectional hardness of the product. If the value is too high, in the process of pipe making, cold bending cracking is prone to occur after bending, and production problems such as cold cracks are prone to occur after welding and cooling. Effectively solving the above problems is related to the enterprise's technological breakthrough in high-grade steel pipeline projects, which is crucial to the long-term development of the enterprise. Contents of the invention ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D8/02C22C38/02C22C38/04C22C38/06C22C38/12C22C38/42C22C38/44C22C38/48C22C38/50
CPCC21D8/0226C21D8/0263C21D2211/00C22C38/02C22C38/04C22C38/06C22C38/12C22C38/42C22C38/44C22C38/48C22C38/50
Inventor 翟冬雨
Owner NANJING IRON & STEEL CO LTD
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