How to Setter Welding Porosity After Sand Blasting

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syeltang87 Active Contributor Join Date: Mar 2010 Posts: 23 Good Answers: 1	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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SolarEagle Guru Join Date: Mar 2007 Location: by the beach in Florida Posts: 33392 Good Answers: 1817	#1 Re: How to setter welding porosity after sand blasting 01/14/2016 11:46 PM
	Why are you sandblasting the part? __________________ All living things seek to control their own destiny....this is the purpose of life
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lyn Guru Join Date: Oct 2008 Posts: 42355 Good Answers: 1693	#2 In reply to #1 Re: How to setter welding porosity after sand blasting 01/14/2016 11:55 PM
	After dressing and buffing?
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syeltang87 Active Contributor Join Date: Mar 2010 Posts: 23 Good Answers: 1	#5 In reply to #2 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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dj95401 Guru Join Date: May 2009 Location: Saint Helens, Oregon Posts: 2216 Good Answers: 70	#7 In reply to #5 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 __________________ Confucius once said, “ Ability will never catch up with the demand for it".
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syeltang87 Active Contributor Join Date: Mar 2010 Posts: 23 Good Answers: 1	#4 In reply to #1 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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dj95401 Guru Join Date: May 2009 Location: Saint Helens, Oregon Posts: 2216 Good Answers: 70	#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. __________________ Confucius once said, “ Ability will never catch up with the demand for it".
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syeltang87 Active Contributor Join Date: Mar 2010 Posts: 23 Good Answers: 1	#6 In reply to #3 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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dj95401 Guru Join Date: May 2009 Location: Saint Helens, Oregon Posts: 2216 Good Answers: 70	#8 In reply to #6 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 __________________ Confucius once said, “ Ability will never catch up with the demand for it".
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#9 Re: How to Setter Welding Porosity After Sand Blasting 01/15/2016 10:43 AM
	Use softer sand. D'oh! __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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SRIDHAR Power-User Join Date: Nov 2006 Location: Chennai - India. Posts: 273 Good Answers: 18	#10 In reply to #9 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 ⁰C 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. __________________ What we have done for ourselves alone dies with us: while what we have done for other and the society remains and is immortal.
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Anonymous Poster #1	#11 In reply to #10 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 ⁰C or so using gas / LPG torch Okay, lets introduce more carbon in to the equation?
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Anonymous Poster (1); dj95401 (3); lyn (1); PWSlack (1); SolarEagle (1); SRIDHAR (1); syeltang87 (3)

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