Hello guys,
I'm facing a big problem with a customer: we overlaid his equipment (designed according to ASME VIII Div1) with a metal core wire 35HRc (as welded). He wants the overlay free of any idication, PT and VT aproved, but in such hardness we have cracks. My question is, there is some acceptance criteria that aproves cracks on overlay welding?
Thank you. Sorry for my bad English, I speak portuguese.
Its probably going to be a difficult sell since your customer is an idiot. But I would recommend contacting the weld material supplier. They should be able to provide ample support for the acceptable existence of cross checking.
Cross checking is normal in hardfacing overlay products - especially at 35 HRC and higher. There are options for crack-free hardfacing but the cost is higher.
More information is needed to give you more help. Did the customer specify the product to be used? Stoody Super Build-Up can achieve 35 HRC without cracking on low carbon steel. There are much more wear resistant products like Stoody 964 that can achieve 50+ HRC without cracking when properly applied. What type of wear is expected for these parts (metal to metal, metal to earth, etc) and are there any corrosion concerns?
Its been awhile but if memory serves the crack free hardfacing alloys are nickel and cobalt based. Thus the cost. Which gives the advantage of high temp applications. We used these for pipe forges and extruders.
Really not necessary if all you are doing is overlaying a bucket on a bulldozer.
The alloys I mentioned are neither cobalt nor nickel based. We (Stoody) developed the 964 line to address these type situations where a reasonable iron-based hardfacing product is needed but cross-checking is considered unacceptable.
That's why I was asking about the type of wear, base metal, corrosion, customer specifications, etc. I suspect that there is an overzealous or under-informed inspector involved....but if not, there are other alternatives.
RA,
WELCOME TO THE ORIGINAL AWS WELDING FORUM!!
If you didn't know, there is a new one also but it is for members only and this one does have a much broader library and reference resource than the new one.
So, I think many of us have run across this on more than one occasion. Many materials will have a 'crack' faced surface after welding. Ever try to 'REPAIR' a part off a cast iron engine on an antique John Deere tractor that the idiot owner left water in through the winter and it froze and broke. I repaired the major broken parts and had a pretty good job done and he explicitly said he just wanted it to keep from allowing water to pour out faster than he could put it in.
When he picked it up, he took it to some non qualified auto shop that had a mag yoke and they "Magna Fluxed" it (guy didn't even know anything about the process and he wasn't even trained let alone certified). Well, he found 'cracks' all over the face of the part. They claimed I had ruined it. I just laughed at them. REALLY? I ruined it when he let it freeze and break in the first place. How many cracks do you think that freeze caused that the part didn't fall out like the ones I actually fixed?
So, to your post, overlay, surfacing, hardfacing, hardsurfacing, all have similar effects. You have different materials that expand, contract, disperse heat, differently and don't ever become the same in that relationship. With the brittle nature of the hard surfacing welds something has to give. As they shrink after welding they crack because they are shrinking at a different rate than the material they are welded to.
As has been noted, some crack less due to the actual composition of the weld being deposited.
But if this is not specified in an original contract, it is the customer who must put out more money and time, not you. You are not a mind reader. You could have no idea of the exact results expected by a customer if they don't spell it out. And, being ASME, it more than likely was the engineer's responsibility to make sure of those kinds of specifications in the Contract Documents.
Once again, it doesn't truly matter if there is some kind of inclusion in any of the codes or a specific code for surfacing, it comes down to what was included in your Contract Documents. Did anyone read them? Did you know what you were looking at? Are you a licensed contractor for the kind of work that was performed?
There is lots here that can come into play that we may not yet have all the facts to.
He Is In Control, Have a Great Day, Brent
