Production method of heavy-wall-thickness X80 pipeline steel

A production method and pipeline steel technology, applied in the field of pipeline steel production, can solve problems such as drop hammer arrest performance constraints, achieve the effect of increasing wall thickness and improving low-temperature crack arrest performance

Active Publication Date: 2018-09-25
HUNAN VALIN XIANGTAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, under low temperature and high pressure service conditions, with the increase of pipeline steel strength grade and wall thickness, DWTT drop hammer crack arrest performance has become a bottleneck restricting the application of high steel grade and large volume pipeline steel engineering.

Method used

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  • Production method of heavy-wall-thickness X80 pipeline steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Embodiment 1: The thickness of the steel plate is 30.8 mm.

[0021] The mass percentage of chemical composition of steel is: C=0.04, Si=0.20, Mn=1.74, P=0.007, S=0.0013, Als=0.032, Nb=0.050, Ti=0.016, V=0.003, Cr=0.18, Mo= 0.11, Ni=0.18, Cu=0.12, B=0.0004, the balance is Fe and unavoidable impurities.

[0022] The production process of steel plate includes clean steel smelting, die casting, first-fire rolling, first-fire billet finishing, second-fire rolling, and steel plate finishing; the key process steps and parameters are:

[0023] (1) Die-casting: Protective casting into a flat ingot by downcasting method, the top is large and the bottom is small, the weight of the ingot is 45t, the width-thickness ratio is about 2.3, the height-thickness ratio is about 3.8, the taper is about 5.1%; the ambient temperature is 6°C, and the degree of superheat is 41°C , the pouring time for the ingot body is 19 minutes, and the pouring time for the riser is 8 minutes; the compressio...

Embodiment 2

[0027] Embodiment 2: The thickness of the steel plate is 30.8 mm.

[0028]The chemical composition of the steel and the production process of the steel plate are the same as in Example 1. The process parameters of die casting and first-fire rolling are the same as in Example 1, and the second-fire rolling billet is another piece of second-fire billet cut from the first-fire billet of embodiment 1, and its second-fire rolling process parameters are: the first-fire billet The reheating temperature is 1050°C, soaking time is 3h; the rolling adopts two-stage controlled rolling, horizontal rolling, widening and longitudinal rolling forming, the finishing temperature of rough rolling is 990°C, the starting temperature of finishing rolling is 820°C, the finishing rolling temperature is 712°C, and the stretching ratio is approx. 2.2, There are 2 passes after widening, the reduction rates are 12.7% and 16.1% respectively, and the thickness of the intermediate billet is 80mm; ACC accele...

Embodiment 3

[0030] Embodiment 3: The thickness of the steel plate is 38.2mm.

[0031] The mass percentage of chemical composition of steel is: C=0.05, Si=0.18, Mn=1.72, P=0.008, S=0.0012, Als=0.028, Nb=0.054, Ti=0.016, V=0.003, Cr=0.17, Mo= 0.12, Ni=0.19, Cu=0.13, B=0.0003, the balance is Fe and unavoidable impurities.

[0032] The production process of steel plate includes clean steel smelting, die casting, first-fire rolling, first-fire billet finishing, second-fire rolling, and steel plate finishing; the key process steps and parameters are:

[0033] (1) Die-casting: casting into flat ingots with lower injection protection, the top is big and the bottom is small, the weight of the ingot is 29 tons, the ratio of width to thickness is about 2.4, the ratio of height to thickness is about 3.4, the taper is about 3.7%; the ambient temperature is 2°C, and the degree of superheat is 43. ℃, the pouring time for the ingot is 16 minutes, and the pouring time for the riser is 7 minutes; the comp...

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Abstract

The invention provides a production method of heavy-wall-thickness X80 pipeline steel. The production method comprises the following production processes: clean steel smelting, die casting, single reheat rolling, single reheat blank finishing, two-times reheat rolling, and steel plate finishing. The steel comprises the following chemical components in percentage by mass: less than or equal to 0.07% of C, less than or equal to 0.30% of Si, less than or equal to 1.80% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.015%-0.045% of Als, 0.040%-0.080% of Nb, 0.008%-0.025% of Ti, less than or equal to 0.030% of V, less than or equal to 0.30% of Cr, less than or equal to 0.30% of Mo, less than or equal to 0.30% of Ni, less than or equal to 0.30% of Cu, less than orequal to 0.005% of B, and the balance of Fe and inevitable impurities. The steel plate sufficiently exerts the advantages of a die cast ingot as a rolling blank, a uniform and fine microstructure withhigh crack extension resistance and appropriate hardness is obtained through twice-heating production, the steel plate thickness is larger than or equal to 30 mm, and the shear area of a full-thickness DWTT drop hammer section at the temperature of 40 DEG C below zero is larger than or equal to 85%.

Description

technical field [0001] The invention belongs to the technical field of pipeline steel production, and in particular relates to a production method of large-wall X80 pipeline steel with excellent low-temperature crack arrest performance. Background technique [0002] The rapid expansion of longitudinal cracks is one of the most serious accidents in pipelines, so the arrestability of ductile fractures is an extremely important aspect in the design of natural gas transmission pipelines. Since the results of the DWTT drop weight tearing test have a good correlation with the results of the physical blasting test of the pipeline, and the test results are less affected by the test conditions, sample processing methods, and sample geometric dimensions, the cost of testing and sample processing is low. The result is stable and reliable, so it has been widely used in the pipeline industry. From the relationship between the shear area of ​​the DWTT drop hammer fracture and the crack g...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/12C22C38/14C22C38/08C22C38/16C22C38/38C22C38/20C22C38/22C22C38/24C22C38/26C22C38/28C22C38/32C22C38/58C22C38/42C22C38/44C22C38/46C22C38/48C22C38/50C22C38/54C21D8/02B22D7/00
CPCB22D7/00C21D8/0226C22C38/02C22C38/04C22C38/06C22C38/08C22C38/12C22C38/14C22C38/16C22C38/20C22C38/22C22C38/24C22C38/26C22C38/28C22C38/32C22C38/38C22C38/42C22C38/44C22C38/46C22C38/48C22C38/50C22C38/54C22C38/58
Inventor 彭宁琦罗登蒋凌枫钱亚军周文浩
Owner HUNAN VALIN XIANGTAN IRON & STEEL CO LTD
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