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How to Setter Welding Porosity After Sand Blasting

01/14/2016 11:12 PM

Hi guy, i have one aluminum part which used tig fillet welding to joint together follow by sand blasting process.( pressure 3 bar, sand grade 100).my problem is after welding i go for dressing and buffing process, the weld surface is ok, no porosity but after i send for sand blast, weld porosity come out. Any one have idea to solve this problem?thanks.

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#1

Re: How to setter welding porosity after sand blasting

01/14/2016 11:46 PM

Why are you sandblasting the part?

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#2
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Re: How to setter welding porosity after sand blasting

01/14/2016 11:55 PM

After dressing and buffing?

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Active Contributor

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#5
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Re: How to setter welding porosity after sand blasting

01/15/2016 12:46 AM

No, the pin hole occur after sand blast

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#8
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Re: How to setter welding porosity after sand blasting

01/15/2016 3:03 AM

The "pin hole" porosity was already there, the blasting just revealed it. You need to look at your processing- parent material is clean, proper filler rod being used, proper shielding gas and the shielding gas not being suck or blown away from the molten puddle during the process

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#4
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Re: How to setter welding porosity after sand blasting

01/15/2016 12:44 AM

Customer requirement. after sandblast will follow by electroless nickel plate

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#3

Re: How to setter welding porosity after sand blasting

01/15/2016 12:41 AM

100# sand = aluminum porosity, your lucky to have anything left after blasting the part. You should be using glass beading or using walnut shells.

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#6
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Re: How to setter welding porosity after sand blasting

01/15/2016 12:49 AM

My mistake for not make the discript clear. We are using aluminum bead blast. thanks

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#7
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Re: How to setter welding porosity after sand blasting

01/15/2016 1:28 AM

What have you done to reduce porosity in the weld?

Here are some tips....see page 25

http://www.hobartbrothers.com/downloads/HobartAluminumGuide.pdf

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#9
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Re: How to setter welding porosity after sand blasting

01/15/2016 3:15 AM

Sorry SE, don't know why my tablet didn't show your post before I posted my last reply GA from me anyhow

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#10

Re: How to Setter Welding Porosity After Sand Blasting

01/15/2016 10:43 AM

Use softer sand. D'oh!

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#11
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Re: How to Setter Welding Porosity After Sand Blasting

01/18/2016 4:56 AM

Porosity in Aluminum has nothing to do with short blasting. It is a common occurrence in AL. welding. As welding temperature is quite high compared to melting temp. of AL Pores are induced, due to solubility of hydrogen during its liquid state and at the time of solidification after welding.

Hydrogen is carried in the welds due to contamination of oil, grease traces (hydro carbons), moisture on the sheet / plate or filler wire or while handling the filler wire if it is a TIG process, humidity in the atmosphere or moisture. To avoid it,

1.Clean the base metal & filler wire (in TIG process) with degreasing agent like acetone, prior to welding,

2.Pre heat on either side of weld zone to 100 0 C or so using gas / LPG torch (to evaporate moisture), clean the area with SS wire brush and continue welding.

3. MIG process will help to do faster and without much distortion.

4. If it is thin sheet and less than 2.00 mm or so, Pulsed MIG process is preferable.

Sridhar.

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#12
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Re: How to Setter Welding Porosity After Sand Blasting

01/29/2016 5:22 PM

2.Pre heat on either side of weld zone to 100 0 C or so using gas / LPG torch Okay, lets introduce more carbon in to the equation?

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