Material Comparisons 1

[Vaultner]

I am working with a product which is investment casted of 4140, through hardened to 400 BHN and surfaced hardened to 550-600 BHN. All kinds of abrasive material impacts and wears down my product as the system processes it.

Examples include: 6" minus material; Rock, broken glass, dirt(compost), wood, paper, plastics

I want to find a material that will deliver better wear properties without making it any more brittle. I am looking at 4340, 8630, and now manganese. Any suggestions would be appreciated whether or not my picks would work, not work; not using "White Iron" which has amazing wear properties but would crack and shatter like a ceramic pot.

 

[ornerynorsk]

Investigate the use of eutectic overlays (hardfacing).

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[arunmrao]

4140, will have poor abrasive resistance, as there are no chromium carbides (M7C3 and M23C6 types) . Have you considered NiHard or High chrome irons for the application?

 

[Vaultner]

The reason 4140 was used was purely availability. I have looked at some higher chrome but haven't looked at NiHard. Is this a readily available material? I looked it up and it is known for wear resistances and can be heat treated to 700 BHN. Of course I don't need it that hard but the wear resistance is intriguing.

 

[arunmrao]

You need to invest cast these parts and heat treat. What is the part,that you want to cast?

 

[Vaultner]

Its a 10 lb disc with impact points used for screening material, not crushing. I believe we lost-wax cast (investment cast) these currently.

 

[arunmrao]

A simple solution can be that you cast in 4140 and at the impact points , create slots/grooves in casting. Later you can embed tungsten carbide bits and braze . This I hope will help, as I have used several times this simple technique.

 

[TVP]

Two very good suggestions: tungsten carbide inserts in the investment cast body or hardfacing/overlay with stellite or similar.

 

[hsemus]

I will prefer F22 material which is much better than AISI 4140.

 

[arunmrao]

TVP, my experience has been that hard facing has a shorter life compared to placing the carbide inserts.

 

[TVP]

Arun,

I agree, the carbide insert option would be best, but it would require a design modification. Hardfacing should be better than straight 4140, and can be deposited directly on the surface, so maybe this could be implemented on a short-term basis while awaiting the longer-term solution.

 

[Vaultner]

In terms of purely the material, 4140 can be through hardened and surface hardened to give a high impact and decent wear resistant part.

I need to maintain the same impact strength or close to it and purely increase wear life. Cost is still a consideration and even small baby steps would help. That's the reason I am looking into 4340 for better wear resistance. I looked into NiHard, but the weld ability is specialized and am unsure of availability. These modifications to the material would be an immediate change where after we would redesign for something like a carbide insert. There are numerous parts per machine and they still need to be mass produced. Cant afford too much individual detail per part as there are hundreds on a machine.