The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform

Hu Shengsun - One of the best experts on this subject based on the ideXlab platform.

  • Effect of deep cryogenic treatment on Electrode Life and microstructure for spot welding hot dip galvanized steel
    Materials & Design, 2003
    Co-Authors: Wu Zhisheng, Shan Ping, Lian Jinrui, Hu Shengsun
    Abstract:

    Abstract In this article, the deep cryogenic treatment technology is first applied in the treatment of Electrodes, for spot welding hot dip galvanized steel plate and Electrode, Life experiment is carried out. The microstructure and elements distribution of the deep cryogenic treatment Electrodes, and non-cryogenic treatment of Electrodes for spot welding hot dip galvanized steel is observed by, scanning electrical microscope and X-ray diffraction. The experimental results shows that deep cryogenic treatment makes Cr, Zr, in deep cryogenic treatment of Electrodes, emanate disperseadly and makes the grain of deep cryogenic treatment of Electrodes, smaller than non-cryogenic treatment ones, so that the electrical conductivity and the thermal conductivity of deep cryogenic treatment Electrodes are improved very much, which makes Electrode Life for spot welding hot dip galvanized steel that improves obviously.

Wu Zhisheng - One of the best experts on this subject based on the ideXlab platform.

  • Effect of deep cryogenic treatment on Electrode Life and microstructure for spot welding hot dip galvanized steel
    Materials & Design, 2003
    Co-Authors: Wu Zhisheng, Shan Ping, Lian Jinrui, Hu Shengsun
    Abstract:

    Abstract In this article, the deep cryogenic treatment technology is first applied in the treatment of Electrodes, for spot welding hot dip galvanized steel plate and Electrode, Life experiment is carried out. The microstructure and elements distribution of the deep cryogenic treatment Electrodes, and non-cryogenic treatment of Electrodes for spot welding hot dip galvanized steel is observed by, scanning electrical microscope and X-ray diffraction. The experimental results shows that deep cryogenic treatment makes Cr, Zr, in deep cryogenic treatment of Electrodes, emanate disperseadly and makes the grain of deep cryogenic treatment of Electrodes, smaller than non-cryogenic treatment ones, so that the electrical conductivity and the thermal conductivity of deep cryogenic treatment Electrodes are improved very much, which makes Electrode Life for spot welding hot dip galvanized steel that improves obviously.

Hiroyuki Kokawa - One of the best experts on this subject based on the ideXlab platform.

  • Degradation mechanism of Electrode tip during alternate resistance spot welding of zinc-coated galvannealed and uncoated steel sheets
    Welding International, 2013
    Co-Authors: Masatsune Kondo, Tokujiro Konishi, Nomura Koji, Hiroyuki Kokawa
    Abstract:

    This study investigated the Electrode Life and the Electrode degradation mechanism during alternate resistance spot welding of galvannealed steel sheets and bare steel sheets. As a result, it was found that the Electrode Life in this type of welding was extremely short in comparison to welding of only galvannealed steel sheets. The reason for this short Life is explained by the sticking of the alloy layers formed on the Electrode top to the bare steel sheet surface, so that the narrower and sharper shape the original Electrode top is the better to prolong the Life. Although the ring-shaped nuggets were not formed during alternate resistance DC welding, the Electrode degradation mechanism is similar to that during the resistance DC welding of only galvannealed steel sheets.

  • Degradation mechanism of Electrode tip during resistance spot welding of aluminium alloy sheets
    Science and Technology of Welding and Joining, 2011
    Co-Authors: Masatsune Kondo, Hiroshi Nagata, Akihisa Nishimura, Hiroyuki Kokawa
    Abstract:

    This study investigated the Electrode Life and the Electrode degradation characteristics during continuous resistance spot welding of aluminium alloy sheets. When a long welding time and dome radius type Electrode were used, the Electrode Life was extended more than that when a short welding time and radius type Electrode are used. The Electrode tip is considered to degrade by the following mechanism: an Al–Cu alloy layer is formed at the Electrode tip during continuous welding, and then it peels off from the Electrode tip transferring to the surface of aluminium alloy sheet. Its peeling makes the Electrode tip indented and finally the Electrode tip flattens with increasing diameter of Electrode tip. In order to eliminate the direct contact between Electrode and worksheet, a special Cu foil insert device for resistance spot welding of aluminium alloy sheets was developed and an extremely long Electrode Life was achieved.

  • Degradation Mechanism of Electrode Tip during Resistance Spot Welding of Aluminium Alloy Sheets
    QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY, 2010
    Co-Authors: Masatsune Kondo, Hiroshi Nagata, Akihisa Nishimura, Hiroyuki Kokawa
    Abstract:

    This study investigated the Electrode Life and the Electrode degradation characteristics during resistance spot welding of aluminium alloy sheets. When a long welding time and the DR type Electrode shape were used, the Electrode Life was much longer than that with a short welding time and the R type Electrode shape. The degradation mechanism of Electrode tip was explained in the following way; firstly, Al-Cu alloy layers were formed at the Electrode top during consecutive welding, and then the layers stuck easily to the surfaces of aluminium alloy sheets so that notable wear took place and the surface profile of Electrode tip became flat. In order to eliminate the direct contact between the Electrode and the sheet, a special Cu-foil insert device for resistance spot welding of aluminium alloy sheets was developed and achieved an extremely long Electrode Life.

  • Degradation mechanism of Electrode tip during alternate resistance spot welding of zinc coated and uncoated steel sheets
    Science and Technology of Welding and Joining, 2010
    Co-Authors: Masatsune Kondo, Tokujiro Konishi, Nomura Koji, Hiroyuki Kokawa
    Abstract:

    AbstractThe operation Life and degradation mechanism of Electrode during resistance spot alternating current welding of zinc coated galvannealed steel sheets were investigated. The Electrode Life in alternate resistance spot welding of zinc coated and uncoated steel sheets was extremely short in comparison with welding only on zinc coated steel sheets. During alternate resistance spot welding, the ring shaped nuggets were formed easily. This is attributable to the sticking of the alloy layers formed on the Electrode top during the previous welding of zinc coated steel, to the uncoated steel surface at the following welding, so that notable wear took place, and the surface profile of Electrode tip became flat. Additionally, an accumulation of highly resistant carbonaceous substance layer at the centre of Electrode top caused an annular flow of welding current to hinder the nugget formation.

  • Degradation Mechanism of Electrode Tip during Resistance Spot Welding of Zinc-Coated Galvannealed Steel Sheets
    QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY, 2009
    Co-Authors: Masatsune Kondo, Tokujiro Konishi, Nomura Koji, Hiroyuki Kokawa
    Abstract:

    This study investigated the Electrode Life and the Electrode degradation characteristics during resistance spot welding of zinc-coated galvannealed steel sheets. As a result, it was found that the Electrode Life in alternate resistance spot welding of galvannealed steel sheets and bare steel sheets was extremely short in comparison with welding of only galvannealed steel sheets. During alternate resistance spot welding, the ring-shape nuggets were formed easily. The reasons for this is explained by the sticking of the alloy layers formed on the Electrode top during previous welding of the galvannealed steel, to the bare steel sheet surface at the following welding of bare steel, so that notable wear took place and the surface profile of Electrode tip became flat. Additionally an accumulation of highly resistant carbonaceous substance layer at the center of the Electrode top caused an annular flow of the welding current to hinder the nugget formation.

Y. Zhou - One of the best experts on this subject based on the ideXlab platform.

  • Effects of Steel Coatings on Electrode Life in Resistance Spot Welding of Galvannealed Steel Sheets
    MATERIALS TRANSACTIONS, 2010
    Co-Authors: Guisheng Zou, Shijie Dong, M. Y. Lee, Jae Pil Jung, Y. Zhou
    Abstract:

    The effects of different galvannealed (GA) coatings, containing Fe varying from 7.0 to 11.4 mass%, on steel sheets on the Electrode Life in resistance spot welding (RSW) have been investigated with metallurgical analysis of the coating microstructures and properties, and the surfaces and cross-sections of failed Electrodes. The results showed that the Electrode Life in RSW of GA steel with 11.4 mass% Fe in coating was 110% higher than that with coatings containing 7.0 or 9.6 mass% Fe. The improvement was believed to be caused by the build-up of a Fe-rich alloy layer on the Electrode surface, which could serve as a barrier to prevent copper loss from the Electrode surfaces to the steel sheets, thus reducing the growth rate of the Electrode tip face diameters. In addition, higher Fe content in the coating resulted in increased contact resistance and hence a lower welding current needed in RSW. [doi:10.2320/matertrans.M2010239]

  • Welding and Joining of Magnesium Alloys - 18 – Resistance spot welding of magnesium alloys
    Welding and Joining of Magnesium Alloys, 2010
    Co-Authors: Lei Liu, J C Feng, Y. Zhou
    Abstract:

    Abstract: Resistance spot welding (RSW) of magnesium alloy is discussed in this chapter. Surface condition is important for RSW of magnesium due to the high chemical reactivity of magnesium and because oxides that form are hard, strong and electrically insulated. Expulsion, weld strength and Electrode Life are all related to surface conditions. Welding conditions (welding current, weld time, Electrode force and weld spacing), nugget growth and dynamic resistance are discussed and compared with those of steel and aluminum alloys. Microstructure of the nugget and the influence of secondary particles are studied in detail. Technologies and mechanisms of dissimilar joining of magnesium alloy to steel and magnesium to aluminum alloys are also discussed.

  • Influence of lubricants on Electrode Life in resistance spot welding of aluminum alloys
    Welding Journal, 2007
    Co-Authors: M. Rashid, Shinji Fukumoto, J. B. Medley, J. Villafuerte, Y. Zhou
    Abstract:

    Rapid Electrode tip degradation and inconsistent joint strength are two major problems associated with resistance spot welding of aluminum alloys. A new approach of lubricating the contact between Electrode and aluminum sheet to influence and perhaps extend the Electrode Life was examined. Different metalworking lubricants were placed between the Electrode and aluminum sheet to produce different surface conditions. Keeping all weld conditions constant, Electrode Life experiments were conducted for both lubricated and unlubricated conditions. Joint shear strength values were periodically measured as hundreds of welds were made until either explosion/sticking occurred or a drop in the shear strength indicated the end of the effective Electrode tip Life. For the same welding conditions and failure criteria, one "good"lubricant was found to extend the Electrode Life to almost double that of the unlubricated surface (as received). A second set of experiments was performed to examine the action of the good lubricant. These experiments involved a variety of smaller studies including scanning electron microscopy, x-ray diffraction, hardness measurements, and electrical resistance measurements. The results of this second set of experiments suggested that the good lubricant thinned the surface oxide layer, thus reducing the heat generation at the Electrode-worksheet interface. This lower heat generation reduced alloying and pitting rate, thus increasing Electrode tip Life. Future work on improving the good lubricant was contemplated.

  • Effects of Electrode Degradation on Electrode Life in Resistance Spot Welding of Aluminum Alloy 5182
    Welding Journal, 2003
    Co-Authors: Shinji Fukumoto, I. Lum, Elliot Biro, D. R. Boomer, Y. Zhou
    Abstract:

    Electrode endurance tests were conducted to investigate the effects of Electrode degradation on Electrode Life in resistance spot welding of 1.5-mm-thick sheet aluminum Alloy 5182 using a medium-frequency direct-current welding machine and Electrodes with tip-face diameter of 10 mm and radius of curvature of 50 mm. The observed Electrode Life ranged from about 400 to 900 welds even though all the process conditions were intentionally kept constant. However, despite the large variation, distinct patterns were found to correlate Electrode Life to Electrode degradation in terms of the change in nominal Electrode tip-face area and contact areas at both Electrode/sheet (E/S) and sheet/sheet (S/S) interfaces. The reduction in joint strength occurred because of undersized nugget formation due to increased contact areas and hence reduced current density. The Electrode degradation may be monitored by the increase in all three areas (nominal tip-face area, and E/S and S/S contact areas), but the E/S contact area is believed to be the most suitable because a minimum of extra work is needed to measure it. The button diameter, measured from peel testing, is affected by nugget diameter (current density) and possibly other factors, such as weld expulsion and porosity distribution as well.

  • Effects of Electrode Degradation on Electrode Life in Resistance Spot Welding of Aluminum Alloy 5182 Degradation of Electrode tip faces increased the contact area at the Electrode~sheet interface, which resulted in an undersized nugget at the sheet~s
    2003
    Co-Authors: Shinji Fukumoto, I Lum, E Biro, D R Boomer, Y Zhou, Shinji Fukumoto, I. Lum, Elliot Biro, D. R. Boomer, Y. Zhou
    Abstract:

    Electrode endurance tests were conducted to investigate the effects of Electrode degradation on Electrode Life in resistance spot welding of 1.5-mm-thick sheet aluminum Alloy 5182 using a medium-frequency direct-current welding machine and Electrodes with tip-face diam- eter of 10 mm and radius of curvature of 50 mm. The observed Electrode Life ranged from about 400 to 900 welds even though all the process conditions were intentionally kept constant. However, despite the large variation, distinct patterns were found to correlate Electrode Life to Electrode degra- dation in terms of the change in nominal Electrode tip-face area and contact areas at both Electrode/sheet (E/S) and sheet/sheet (S/S) interfaces. The reduction in joint strength occurred because of undersized nugget formation due to increased contact areas and hence reduced current density. The Electrode degradation may be moni- tored by the increase in all three areas (nominal tip-face area, and E/S and S/S con- tact areas), but the E/S contact area is be- lieved to be the most suitable because a minimum of extra work is needed to mea- sure it. The button diameter, measured from peel testing, is affected by nugget di- ameter (current density) and possibly other factors, such as weld expulsion and porosity distribution as well.

Luo Xian-xing - One of the best experts on this subject based on the ideXlab platform.

  • Electrode Life and surface characteristics in resistance spot welding of aluminum
    Materials Science and Technology, 2005
    Co-Authors: Luo Xian-xing
    Abstract:

    To analyze the characteristics of Electrode degradation in resistance spot welding of aluminum with different weld powers,and its influence on weld quality,An imaging approach was developed based on the analysis of Electrode Life test results to quantitatively determine the status of Electrode degradation.According to the analysis on the carbon imprints of Electrode tips,three parameters were defined to represent the tip surface characteristics: relative radius(Rr),edge concentration(EC) and eccentricity(ECC).The results show that in resistance spot welding of aluminum,the Electrode Life for MFDC machine is about 1/4 of that for AC machine.The sheer strength of test welds decreased with the increase of Rr and EC.The remained contact area in the center of the tip surface help to maintain satisfactory weld quality.