Welding cooling rate effects on microstructure of an API 5l x100 steel

 
 
 
  • Abstract
  • Keywords
  • References
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  • Abstract


    The aim of this work was to investigate the influence of five different cooling rates on properties of weld metal (WM) and heat affected zone (HAZ) of an API 5L X100 steel welded by GMAW. Bead on pipe (BOP) welds were made on 100x300 mm sections of a 15.8 mm thickness and 580 mm outside diameter API 5L X100 pipe, through five preheat temperatures (-30, 34, 100, 150 and 200 °C), aiming to obtain different cooling rates. Thermocouples were used to obtain the cooling time from 800 to 500 ºC (Δt8/5) during welding. The microstructures of base metal (BM) and HAZ were analyzed by light microscopy and scanning electron microscopy (SEM). Hardness measurements were made on the BOP welds in order to identify maximum and minimum values. As expected, due to the different cooling rates during welding, the distinct preheat temperatures have influenced the weld properties. Maximum and minimum HAZ microhardness, and weld metal hardness decrease as the preheat temperature increases. HAZ area, grain size of fine grained HAZ and coarse grained HAZ increase with increasing preheat temperature.


  • Keywords


    Welding; API 5l X100 Steel; Cooling Rate; Mechanical Properties; Heat Affected Zone.

  • References


      [1] Thewlis, G., Weldability of X100 Linepipe - Science and Technology of Welding and Joining, 2000, VOL5 N° 6. http://dx.doi.org/10.1179/136217100101538434.

      [2] M. K. Gräf, H. G. Hillenbrand, C. J. Heckman and K. A. Niederhoff, High-strength large pipe for long-distance high pressure gas pipelines, Int. J. Offshore Polar Eng., 2004, 14, 69–74.

      [3] L. Barsanti, H. G. Hillenbrand, Possible use of new materials for high pressure line pipe construction: The experience of SNAM RETE GAS and EUROPIPE on X 100 grade steel, Proceedings of IPC: The International Pipeline Conference, Calgary, Alberta, Canada, 2002. http://dx.doi.org/10.1115/IPC2002-27089.

      [4] Hudson, M. G., Welding of X100 Linepipe. 2004. PhD Thesis – School of Industrial and Manufacturing Science. Cranfield University.

      [5] American Petroleum Institute, API Specification 5L/ISO 3183, 2009.

      [6] Machado, I. G., Condução do Calor na Soldagem: Fundamentos & Aplicações. Porto Alegre, 2000. v. 1. 101p.


 

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Article ID: 6113
 
DOI: 10.14419/ijet.v5i2.6113




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