Cosmetic Repair of 4140 machining error 1

[mfritze]

Hello,

I need to disposition a part where the machinist goofed and gauged a small (1/8") cosmetic defect into a structural part. The part is 4140 Q&T to 35-40 HRC. I would prefer not to weld repair this defect as I am unsure of the effects of the welding on the heat-treated 4140. Although if anyone has a quality reference on welding heat-treated 4140 successfully I would certainly consider.

This part is going to get electroless-nickel plated. Is there a solder or braze that might work to fill this defect, not affect the parent material heat-treat properties, and able to be electroless nickel plated? I am thinking a low temp material that bonds to steel and is able to plated might fix these nicely but do not know of such a material.

Thanks,

 

[Tmoose]

Does the designer/engineer agree it is a cosmetic defect.

Just sayin' .

regards,

Dan T

 

[redpicker]

Blend it by grinding to form a smooth contour and submit it to the customer for acceptance. If it will not affect form, fit, or function, you may have a chance. I wouldn't try to repair it by filling. If blended is unacceptable, anything that is done to fill it that gets discovered after it is put into use will be a much bigger problem than just scrapping it now.

 

[arunmrao]

3M has some good products, that might help. These are cold setting with different metal fillers, they can be machinedor ground subsequently.Any thermal process like metal spray, can affect the properties.


"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[mfritze]

Ok thanks. It's in a little hoop that serves as a lanyard holder for a quick-release pin -so its in a non-structural area (and fracture Fail-Safe). I might see how well we can blend it.

 

[metengr]

I would also suggest you perform a surface NDT (wet MT or Liquid Penetrant test) after blend grinding to ensure no cracks or other defects present.