cracked pump-hardfacing effects?
cracked pump-hardfacing effects?
(OP)
i used a hardface welding (300 Amp)inside our dredgepump housing to avoid wear on pump inner surface. however, after several months, the crack line occured on the surface of the unwelded. Could this things happen because of the hardfacing weld? we are using the pump casing which made by maxidur 5 material which can withstand a friction of materials from 0.06mm to 6mm for at least 2 years.





RE: cracked pump-hardfacing effects?
Based on the above information, this cast iron has very poor weldability. You are in a tough situation because having performed hardface welding and attempting to re-repair will be difficult, at best.
The only repair scenario I can think of is to remove the crack from the pump case, and locally weld restore using a Nickel-base weld rod under a high preheat (500 deg F). If you can deposit this nickel-base weld layer over the repair area, you can deposit the hardface on top of this material.
I would start looking at replacement pump casings.
RE: cracked pump-hardfacing effects?
I make these pump castings and any increase in heat input during rough grinding causes the parts to crack. Welding is never a good option,though I have got away with it in non working areas and in stationary parts.
RE: cracked pump-hardfacing effects?
RE: cracked pump-hardfacing effects?
At this moment Molybdenen is extremely expensive. For this reason Max 5 is very tricky. If it's content is reduced or completely left out of the alloy (and we have seen this), it produces a hard case (60-65 HRC) around a softer core. Most dredgers only look at hardness values in there acceptance criteria and will not notice this. In service the hard surface will wear off exposing the softer material.
A good and at this moment cheaper alternative can be Nihard 4. This alloy does not contain Molybdenen and is precipition hardened leaving a uniform hardeness throughout the wall thickness. I dont think it is possible, or at least economically feasable, to sheat on this alloy. The hardness you measure at the surface is the same (within a marginal reduction of 2 or 3 points) as at the inside.
The patterns used for Max 5 can also be used for Nihard 4.
RE: cracked pump-hardfacing effects?
RE: cracked pump-hardfacing effects?
Thank you for the star, I'm flatered.
What do you mean with the issue on the carbide types?
RE: cracked pump-hardfacing effects?
i just follows the references i made to the smit-weld which claims that the maxidur 5 can be hardfaced by using the sterno 40FMC welding electrodes with some precautions. when the pumps start cracking, i aware that something going wrong during the process. i not yet analyse in the materials used for the electrodes.
gieter,
where can i refer the contetnt and material composition for
1. Maxidur 5
2. Maxidur Top
3. Maxidur R
4. Nihard
one thing, i'll discuss with a local pump manufacturer here to fabricate a new pump casing for my usage. What factor should we pay a lot of attention in order to improved our maxidur 5? any suggestions?
RE: cracked pump-hardfacing effects?
There are different grades of Nihard developed by NIDI. The most used is grade 4 which is a GX300CrNiSi9.5.2 containing about 3% C, 8-10% Cr, 4-7 Ni and 1.5-2% Si.
This material is very well documented by NIDI. Have a look at their site http://www.nidi.org
Both alloys are high alloyed white cast irons and only obtain their optimum properties after appropriate heat treatment.
Maxidur TOP is some sort of steel plate with an abrassion resistant cladding (I think welded) and Maxidur R is claimed to be a bimetalic cast material with a soft carrier material and a hard top. Both are not suted for dredging pump housings at this time.
RE: cracked pump-hardfacing effects?
i can weld the casing but, as you said, now its time to look for replacements. gieter proposed to used Nihard grade 4. How 'bout you? any suggestion to improved my pump rather than max 5 or nihard?
RE: cracked pump-hardfacing effects?
RE: cracked pump-hardfacing effects?
RE: cracked pump-hardfacing effects?
If it was me, I would go with arunmrao's recommendation in using the 15Cr-3Mo grade of casting for this application. He is involved with supplying castings, so I would follow his advice.
RE: cracked pump-hardfacing effects?
thanks for your recommendation. in order to get the best performance, many consideration has to be made. either using 15Cr-3Mo or Nihard, both have thier own advantage and disadvantage. However, i need to consider the market price and availability for all materials involved such as Mo, Si, Ni (not including Cr, Carbon and iron as base materials)in asian region. And i have no doubt to again use max 5 with some other precaution in the system itself. Sometimes, doesn't mean the best is the 'best'. sometimes, the worst could be best. The best way for us (maybe) to think the way to improve our existing parts by applying suggestion and experiences which was discussed in this forums.
your kind comments and recommendation is always welcome.
RE: cracked pump-hardfacing effects?
Below are list of the links to image taken for failed pumps for you to get the clear pictures for comments
1. http://tinypic.com/kf31ch.jpg - Failures on wearing plate
2. http://tinypic.com/kf32th.jpg - Location of the fails
3. http://tinypic.com/kf32x5.jpg - Cracked casing
4. http://tinypic.com/kf333k.jpg - Crack
*Please post yout comments
RE: cracked pump-hardfacing effects?
Hence your attempt in knowing the price of Mo,Ni etc may not be very useful.