1 / 30

“ The low hydrogen covered electrode ”

“ The low hydrogen covered electrode ”. Alexandre Queiroz Bracarense Claudio Turani Ezequiel Caires Pereira Pessoa Ivanilza Felizardo Federal University of Minas Gerais Belo Horizonte, MG, BRAZIL. It is an extreme condition, where the electrode (usually E6013).

bevis
Download Presentation

“ The low hydrogen covered electrode ”

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. “The low hydrogen covered electrode” Alexandre Queiroz Bracarense Claudio Turani Ezequiel Caires Pereira Pessoa Ivanilza Felizardo Federal University of Minas Gerais Belo Horizonte, MG,BRAZIL

  2. It is an extreme condition, where the electrode (usually E6013) Everything started with underwater wet welding needs to be varnished Many varnishes were tested including Expanded polystyrene (Styrofoam™) dissolved in chloroform QUESTION:What could happens if the polymer is placed directly on the coating as a binder and sealer? Could it eliminates the varnishing needs?

  3. In the Laboratory Electrodes produced in the laboratory

  4. Manufacturing Raw material Briquette press Binder Electrode extruder Briquette Briquette Dry mix Wet mix Dry mix Balance Mixer Mixer Covered electrode Wire Dry mix area Wet mix area Extrusion area Package Drying area Drying 150°C 2hours Air cooling Traditional flow For undewater Varnishing Package Drying area Air drying NEW FLOW (Impermeable E6013 covered electrode)

  5. Evaluation of extrudability E6013 E6013

  6. Important surprise, yet inexplicable! Microstructure of underwater wet weld made with E6013 electrode waterproofed with VINILIC varnish PF + WF + 500x WF + PF + 500x Typical!!!! 100x

  7. Microstructure of underwater wet weld made with E6013 electrode binded with POLYSTYRENE AF + AF + F P + 500x 500x 100x

  8. Full with ACICULAR FERRITE!!!! Acicular ferrite is an indication of good mechanical properties. It is difficult to obtain acicular ferrite in underwater wet welding!! Using the polymer it was easily obtained!!!

  9. The underwater project still goes on, however…. the focus turned to…. .....conventional welding with E7018 This new technology could eliminates redrying, maintenance and more......

  10. Basic electrode fabrication Raw material Briquette Press Binder Electrode extruder Briquette Briquette Dry mix Wet mix Dry mix Balance Mixer Mixer Covered electrode Wire Dry mix area Wet mix area Extrusion area Package Drying 150°C 2hours Baking 400°C 9hours Air cooling Package Drying area Air drying New flow (Impermeable E7018 covered electrode)

  11. Methodology 1st PHASE: Adjustments in the conventional formulation of basic type E7018 covered electrodes, replacing the silicate by polymer in solution and manufacturing in laboratory. Electrodes produced in the laboratory

  12. Methodology 2nd PHASE: Production, in industrial scale, of batches of impermeable E7018 electrodes. Electrodes produced in the factory

  13. Methodology • Production Validation tests: Bead on plate • Arc stability • Bead appearance • Chemical composition • Microstructure • Diffusible hydrogen • Hardness Validate formulae changes Direction for new changes

  14. Results First good results – Economy of water and energy!!! Considering the annual E7018 (3,25mm) Brazilian market: 2,000 tons per month In the factory Conventional electrodes In 12 months = 24,000 tons = 8,500 tons of powder = 2,300 tons of silicate = 1,400,000 liters of water + drying energy with natural gas = Impermeable electrodes In 12 months = 24,000 tons = 8,500 tons of powder = 648,000.00 USD 0 liters of water + no pre-drying 648,000.00 USD/year Economy

  15. Results Welds of Electrodes produced in the laboratory Weld of Electrodes produced in the factory

  16. Results More good results – Economy in maintenance In the Client Conventional electrodes Pre-drying and maintenance: 538,700 KwH/year Impermeable electrodes Pre-drying and maintenance: 0 KwH/year 120,415.29 USD/year Economy

  17. Results welding current Considering an E7018 (3,25mm) with a deposition rate of 1,09Kg/h Conventional electrodes Voltage: 24Volts and Current: 130A Consume (24,000 Tons/year): 68,697,247 KwH/year Impermeable electrodes Voltage: 24Volts and Current: 110A Consume (24,000 Tons/year): 58,128,440 KwH/year 10,568,807 KwH/year Difference = Economy

  18. Results impermeable conventional Weld Metal chemical analyses Hardness at acicular ferrite regions ~ 270 HV

  19. Results Weld metal microstructure – different positions Top Center Root 100X 500X 1000X Nital 2%

  20. Results Still Acicular ferrite!!!!!

  21. Results Tensile test Tensile stress 677,9 MPa Yield stress 554,3 MPa Elongation after rupture 29,1 %

  22. Results Impact Test– Charpy V (- 30oC) Absorbed energy at -30o C = 68 J (- 45oC) Absorbed energy at -45o C = 50 J

  23. Results SLAG X-ray Diffractometry Conventional The slag analysis for the conventional electrode showed that the compounds were not all used during the burning through the arc, probably indicating that they are in excess in the formulae. On the other side, for the impermeable covered electrode, the x-ray pattern showed few peaks (an unusual morphology for slags) indicating probably that most of the compounds were burned during the welding. This is probable the phenomena associated with all the benefits observed in weld metal. Impermeable

  24. Results Fume analysis – ion chromatography Dangerous materials: aluminum, Fluor, iron oxides, magnesium, manganese and vanadium. Conventional electrode Particulates Probable due CaF2 - traces Fumes Went up until stabilize

  25. Results Fume analysis – ion chromatography Impermeable electrode Particulates Fumes Gas flow was turned off Larger scale No indication No indication

  26. Results Diffusible Hydrogen – Cromatography

  27. AWS Standard

  28. Results Diffusible hydrogen (Commercial E7018 – 7,5m/100gr) 15 days v 60 days v 30 days Lot 1 – mixer type “paddle mixer” Lot 2 – mixer type “screw blender”

  29. Results Diffusible hydrogen IMPORTANT OBSERVATION: Seems that the impermeable electrode “exposure” doesn’t promote the hydrogen content increase and even reduce it …..

  30. Remarks regarding to the findings • It is possible to be produced the electrode in large scale; • Electrode with excellent operacionability (lower current); • Undetermined durability – hydrophobic coating; • Excellent coating mechanical resistance; • Can save a lot of money; • Waive special maintenance and conservation; • Superior mechanical and metallurgical results related to conventional electrodes; • Technology applies for others coatings types; • Very low hydrogen weld metal - the possibility of approval the electrode as E7018-1H4R, H2(??) or whether the standard permits….

More Related