In general, nickel-based alloys will exhibit both sluggish welding and shallow penetration characteristics...Therefore, care must be used with respect to joint design and weld bead placement to insure that sound welds with proper weld bead tie-in are achieved... The nickel-based alloys have a tendency to crater crack, so grinding of starts and stops is recommended...
Selection of welding filler materials is a critical element in the design of a corrosion-resistant welded structure... Often, several types of corrosion-resistant alloys are used at various locations in the same structure... The selection of welding filler materials for dissimilar metal joining applications is also critical...
Two methods of welding filler material selection are possible...
They are (1) selection of matching filler materials and (2) selection of over alloyed filler materials... When the matching filler material technique is used, the filler material is of the same chemical composition as one or both of the base materials... In dissimilar welding applications, using the matching filler material technique, the filler material is chosen to match the base material which is generally more highly alloyed (more corrosion resistant)... With the over alloyed filler material selection technique, a highly alloyed, highly corrosion-resistant welding filler material is used... Over alloyed filler metal selection reduces the chance of preferential weld metal corrosion attack... In addition, the use of a single over alloyed filler material on a job site greatly reduces the chance of filler metal mix-up...
When joining the Hastelloy alloy base materials to carbon steel or low-alloy steel, the arc may have a tendency to play onto the steel side of the weld joint... Proper grounding techniques, a short arc length and torch/electrode manipulation are necessary to compensate for this problem...
It should be recognized that nickel-based alloy weld metal is sluggish (not as fluid as carbon steel) and does not flow out as
readily and
"wet" the sidewalls... Therefore, the welding
arc and filler metal must be manipulated so as to place the molten metal where needed... In addition to the sluggishness, the joint penetration is also less than that of a typical carbon or stainless steel weld... With this low penetration pattern,
the possibility of incomplete fusion increases... As a result of these factors, care must be taken to
insure that the groove opening is wide enough to allow proper torch or electrode manipulation and placement of the weld bead...
The welding surface and adjacent regions should be thoroughly cleaned with an appropriate solvent prior to any welding operation... All greases, cutting oils,crayon marks, machining solutions, corrosion products,paints, scale, dye penetrant solutions, and other foreign matter should be completely removed... Stainless steel wire brushing is normally sufficient for interpass cleaning of GTAW and GMAW weldments... (200 Degree F Max. before restarting welds)
The grinding of starts and stops is recommended for all
fusion welding processes... If oxygen or carbon dioxide bearing shielding gases are used during gas metal arc welding,
light grinding is necessary between passes prior to wire brushing...Knowing the specific Hastelloy type/grade and chemical composition is vital to insure you are using the appropriate and optimal filler metal especially when dissimilar welding... Buttering the 316L side of the joint with the recommended Hastelloy X (ERNiCrMo) filler metal could make it easier to fuse than with the inconel 182 (ERNiCr) that you are using currently because the Molybdenum in Hastelloy x which enable better wetting characteristics... And it would also would reduce dilution which is critical in dissimilar welds once you weld the 2 members together... As mentioned previously, increased bevel angle should be used on the Hastelloy side, and the root gap could also be increased slightly depending on the joint in question...
Are you using an Argon, Helium, Carbon Dioxide, or a instead of Helium, replaced by Oxygen is in the tri-mix? Is inconel 182 the recommended filler for that dissimilar metal joint? Why not use a Hastelloy alloy that matches the Hastelloy base metal or over alloying the weld deposit instead? As far as not knowing what the PQR shows, the parameters you listed cannot be used to recommend any changes if necessary...
Here's a guide for welding filler metal information including dissimilar welding:
http://www.haynesintl.com/pdf/h3159.pdfUse page 23 as your welding filler metal guide for Hastelloy X. Go first to page 24 to find Hastelloy X then to page 25 for group II base metal combinations for dissimilar welding... Once there look @ the corresponding numbers of the recommended alloy filler metals to use for your metal combination and then go on to page 26... Group II recommends numbers 3 and 14 respectively. so you have to go back to page 24 to find out each of the numbers listed which are 3,14... Number 3 is Hastelloy X and number 14 is Haynes 556 Alloy to over match...
Here's 2 brochures on Hastelloy X:
http://www.haynesintl.com/pdf/h3009.pdfhttp://www.haynesintl.com/pdf/h3149.pdfHere are some guides with welding information for various Haynes products including Hastelloy grades:
http://www.haynesintl.com/search.asp?zoom_query=welding+smart+guideThere's probably more to add on what to look out for when you visit your customer but without knowing the details, all we can do is offer a few suggestions. So that's it for now... Lawrence has much more experience in dissimilar welding of Hastelloy with various alloy compositions so look out for his comments as well... And fschweighardt is correct in adding .5 to 1% Carbon Dioxide to the mix for better penetration... Bottom line is this... Call Haynes International in Kokomo, IN as Len mentioned earlier in order to match the correct filler metal for dissimilar welding of Hastelloy X to 316L Stainless steel... Good luck.
Respectfully,
Henry