Effect of Independent Anode on Ion-nitriding Process of Oil Drill Pipe Inner Wall

FENG Tao, LIU Bin, WANG Yin-zhen, YANG Qing-lin, LIU Jun

Surface Technology ›› 2019, Vol. 48 ›› Issue (5) : 65-71.

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Surface Technology ›› 2019, Vol. 48 ›› Issue (5) : 65-71. DOI: 10.16490/j.cnki.issn.1001-3660.2019.05.010
Special Topic—Corrosion and Protection of Petroleum Pipes and Equipment Materials

Effect of Independent Anode on Ion-nitriding Process of Oil Drill Pipe Inner Wall

  • FENG Tao, LIU Bin, WANG Yin-zhen, YANG Qing-lin, LIU Jun
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Abstract

The work aims to improve the performance of the inner wall of oil drill pipe by pulsed ion-nitriding. An inde-pendent anode was inserted into the oil drill pipe, and the inner cavity of the drill pipe was used as the nitriding furnace to complete the ion-nitriding on the inner wall of the drill pipe. By measuring the temperature distribution of the nitriding process, hardness distribution, corrosion resistance and friction and wear properties on the cementation layer were determined and the influence of the independent anode size on the nitriding process of the drill pipe inner wall, the microstructure of the cementation layer, and the wear resistance and corrosion resistance of the drill pipe was analyzed. The temperature field of L1700 anode was more uniform than that of L600 anode. When L600 anode was used, the thickness of infiltration layer decreased with the increasing distance from anode. When L1700 anode was used, the morphology and thickness of infiltration layer were distributed symmetrically. After nitriding, the micro-hardness of nitriding layer decreased gradually from the surface to the inside. By comparing the two different anodes, the hardness of L1700 changed more slowly. Salt spray corrosion and friction and wear tests showed that when L600 anode was used, the performance decreased with the increase of distance, while when L1700 anode was used, the performance was symmetrically distributed, with the lowest performance at the middle position. The inner wall of drill pipe can be nitrided by the method of built-in independent anode. The influence range of independent anode is about 260 mm. With L1700 anode for nitriding, the maximum surface hardness can reach 848.0HV0.2, and the minimum thickness of the layer is 0.33 mm. The corrosion test shows that the maximum corrosion rate of L1700 sample is 1.6917×10?5 g/(mm2·h), and the maximum wear rate is 1.5513×10-7 mm3/(N·m).

Key words

oil drill pipe; inner wall ion-nitriding; independent anode; hardness; wear resistance; corrosion resistant

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FENG Tao, LIU Bin, WANG Yin-zhen, YANG Qing-lin, LIU Jun. Effect of Independent Anode on Ion-nitriding Process of Oil Drill Pipe Inner Wall[J]. Surface Technology. 2019, 48(5): 65-71
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