Harden-ability of 4130
Harden-ability of 4130
(OP)
Currently looking at doing some HT on some rather large cross sections of 4130. What is the average through hardness depth that is usually seen out of 4130? I keep getting a wide range of values, but from what I have heard it is about 2 inches which seems low... going to be HT,Qenched and Tempered to 235 HBW max.
Looking at 3 different specimens: 20"x 17"x 44" , 20"x 17"x 24", and 21"x 18"x 65", all with a 2" through bore drilled through the entire length.
Looking at 3 different specimens: 20"x 17"x 44" , 20"x 17"x 24", and 21"x 18"x 65", all with a 2" through bore drilled through the entire length.





RE: Harden-ability of 4130
RE: Harden-ability of 4130
RE: Harden-ability of 4130
To achieve maximum hardness with 4130, israelkk's thickness suggestions are in line with my own experience. But getting the material below 235 HBW will require basically an anneal step after the harden, and I'd guess it will be that same hardness all the way through even large sections.
RE: Harden-ability of 4130
Current process will be: Normalize at 1700F for 5.5hr, then Austenitize at 1600F 5.5hr, quench below 400F, then temper at 1200 for 11 hours, finally ending with air cooling...
With this current process you're saying I should have full through hardness, even through 11" sections? Or I should expect only .5"?
-M
RE: Harden-ability of 4130
RE: Harden-ability of 4130
-M
RE: Harden-ability of 4130
After the 11 hour temper at 1200°F (equivalent to a subcritical anneal), I believe the part will be the same (low) hardness all the way through even 11".
An 80 ksi minimum yield strength might required a minimum UTS of around 120 ksi (very approximately, yield-UTS relationships vary by alloy and part geometry). 120ksi UTS actually correlates to a little above a 235 BHN hardness. Absent previous data on tensile testing from similar parts, meeting the minimum yield strength would be more my concern than having a uniform annealed hardness level throughout the part.