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Steel plate for low temperature pressure vessel 15MnNiNbDR shall comply with GB 3531-2014
來源: | 作者:pmod34d68 | 發布時間: 2020-01-04 | 1083 次瀏覽 | 分享到:
The grade of 15MnNiNbDR steel is indicated by the average carbon content, the letter of alloy element and the first letter of Chinese Pinyin for "low" and "capacity" of low-temperature pressure vessel. The maximum thickness of 15MnNiNbDR steel currently used is 60mm.
The grade of 15MnNiNbDR steel is indicated by the average carbon content, the letter of alloy element and the first letter of Chinese Pinyin for "low" and "capacity" of low-temperature pressure vessel. The maximum thickness of 15MnNiNbDR steel currently used is 60mm.

With the development of large-scale petrochemical construction projects, there are more and more spherical pressure vessels filled with low-temperature medium, and the requirements of low-temperature spherical tanks are stricter than those of normal temperature spherical tanks in terms of design, material selection, manufacturing, installation and acceptance. In gb3531 low alloy steel plate for low temperature pressure vessel, the technical requirements for low temperature impact toughness of 16MnDR and 15MnNiNbDR are - 40 ℃ Akv ≥ 24J, and - 45 ℃ Akv ≥ 27j, respectively. In order to meet the construction demand of domestic large-scale petrochemical ethylene spherical tank with lower temperature, some steel plants add micro elements such as V, Nb, Ni etc. which are allowed by gb3531 on the basis of greatly improving the metallurgical quality of steel. High performance 15MnNiNbDR (- 50 ℃ low temperature impact Akv > 60j, σ B ≥ 530mpa) steel plate was successfully developed.

Market application of 15MnNiNbDR

The project belongs to the field of metal material processing and manufacturing technology. The steel for low temperature pressure vessel is developing towards high toughness and high strength. The steel grades in the current steel standard gb3531 for low temperature pressure vessel can not fully meet the market demand. In order to meet the market demand for high toughness (- 50 ℃), high strength (RM ≥ 530) low temperature pressure vessel steel, 15MnNiNbDR steel was developed

1) Advanced smelting processes such as Kr desulfurization, top and bottom combined blowing, RH vacuum treatment and protective casting in the whole process of continuous casting are adopted to fully reduce the content of S and P and gas inclusions in the steel and improve the purity of the steel;

2) By reducing C content, adding alloying elements Ni and Nb, the second phase particle dispersion distribution of carbonitride of element NB formed by strong carbides in steel is used to refine grains and improve the strength, low temperature toughness and weldability of steel;

3) The stable ferrite pearlite structure was obtained by the heat treatment process of yidang, and the structure of steel plate remained stable after heat treatment, welding and SR treatment;

4) At the same time, the welding materials, forgings and other supporting materials required for the application of steel plate engineering were researched and developed, and the localization of engineering materials, manufacturing and installation of low-temperature spherical tanks was realized.

Smelting method and ultrasonic detection of 15MnNiNbDR

15MnNiNbDR steel is smelted by oxygen converter or electric furnace, and external refining process should be adopted.The compression ratio of continuous casting slab and ingot shall not be less than 3, and that of electroslag remelting slab shall not be less than 2.

Each steel plate delivered in normalized or normalized plus tempered condition with a thickness of more than 20 mm and in quenched plus tempered condition with a thickness of more than 16 mm shall be subject to ultrasonic testing, and each steel plate of other thicknesses may be subject to ultrasonic testing after negotiation between the supplier and the demander. The testing method shall be in accordance with JB / t4730.3 or GB / t2970.

15MnNiNbDR surface quality
No cracks, bubbles, scabs, folds, inclusions and other defects are allowed on the surface of the steel plate. If there are the above surface defects, cleaning is allowed. The cleaning depth shall not exceed half of the tolerance of the thickness of the steel plate from the actual size of the steel plate, and the minimum thickness of the steel plate shall be ensured. The defect cleaning place shall be smooth without edges and corners, and the steel plate shall not be layered.

Other defects are allowed. The depth shall not exceed half of the thickness tolerance of the steel plate from the actual size of the steel plate, and the thickness of the defect shall not be less than the allowable thickness of the steel plate.


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