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From the field experience of many of the inspector or contractor in the field is less comfortable with the downhill progression due to the assumption that less penetration.


This assumption is indeed justified, but must also be understood from the design calculation, not all members want deep vertical fillet weld penentration, sehinnga downhill progression in certain circumstances can help productivity without reducing the necessary requirements.


Article below can give you a little picture of technik downhill progression.

We use either downhill or Uphill welding in the vertical position. Downhill welding is carried out with a Downward progression, conversely, Uphill moves in an upward progression. Downhill welding is often Used for fillet welding of steel sheets due to the Following advantages over Uphill welding.


(1) Faster speed welding

(2) Easier to obtain small-leg fillet weld

(3) shallower penetration

(4) Lower heat input due to faster welding speed

(5) Less welding distortion


However, downhill welding cans inhibit penetration and slag inclusions generated unless a WELDER arc to Can control the tracks Correctly on the welding line at fast speeds (eg 60 cm / min or higher with A 1.2-mmφwire). The Following Can Prevent measures defects in vertical fillet welding downhill.


(1) Use the straight run without weaving technique.

(2) Control the welding torch so That the work angle is 45 degrees and the drag angle, 5-15 degrees as

shown below.




Another difficulty with downhill welding is That it tends to cause a concave bead having an insufficient throat (concavity) in the vertical fillet welding. To overcome this problem, two-layer welding is recommended as shown in the Following figure. Even in the second layers, again, use the straight run without weaving technique.


With respect to the welding wires suitable for downhill welding, the Following choices are recommended in conjunction with suitable mode of droplet transfer and application.


(1) Solid wires for welding sheet metals by using a short-circuiting the arc at the low current range (eg 50 - 160A for 1.2mmφ wire), Standard and Poor 'MG-51T (ER70S-6)

(2) Flux-Cored wires for welding sheet metals by using a short-circuiting the arc at the low current range (eg 50 - 180A for 1.2mmφ wire), Standard and Poor 'MX-100T (E71T-1, E71T-1M)

(3) Flux-Cored wires for welding thin plates by using a globular arc at the middle range to high current (300A for 1.2mmφ eg200-wire), Standard and Poor 'DWA-50 (E71T-1M), DW-100 (E71T -1), DW-110 (E71T-1), and MX-Z210 (E70T-1)


Before employing downhill welding, weldpenetration, joint alignment tolerance and the WELDER's skill Should be thoroughly examined to Ensure That the weld Satisfies the requirements. For your information, AWS D1.1 (Structural Welding Code - Steel), for example, specifies That a change from Uphill to downhill or vice versa is the essential variable requiring requalification of the welding procedures specification.