Heat Treating 4130 for toughness

[hillmd92]

We are experiencing problems coming up with the best “recipe” for heat treating a 4130 part for toughness (not hardness). Can anyone provide the best parameters for:
- Austentizing
- Quenching
- Tempering

 

[Metalguy]

Part thickness? 1575 F, water quench. Temper 1000 MINIMUM.

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein

 

[hillmd92]

The part is 0.070" thick. We are currently doing the following which is resulting a a brittle part and a 43RC:
- 1585F for 1 1/2 hours
- Oil quench to room temp (oil maintained at 60°c)
- Temper at 750F for 2 hours
- Air cool to room temp

What have you found to be the most significant factor in making 4130 tough?

 

[Metalguy]

your hold time at 1585 is way too long. Try ~20 min. Then temper at 1,000 F minimum. What hardness do you need?

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein

 

[hillmd92]

We are quickly learning that toughness is more critical than hardness in this application. We were originally shooting for a hardness of RC 43 - 45 to resist drilling/punching etc. This is no long as critical as toughness - resistance to cracking/tearing.

I have attached a drawing so you can get a better idea of the shape of the part.

 

[cloa]

Hillmd92 Try again with the attachment

 

[hillmd92]

Sorry, new to this.

 

[Metalguy]

You should get Rc32 if you temper at 1,000F. Toughness of 4130 increases dramatically from 900 F to 1000F.

Many high pressure gas cylinders (oxygen, etc) are 4130 and tempered at 1,000 F min. Cylinders are VERY tough.

If cost counts, consider using 1030 and water quenching. Will be approx. the same hardness and toughness in such a thin part.

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein

 

[hillmd92]

What happens over 1000F?

 

[Metalguy]

~Rc28, very slight increase in toughness. Use a TRUE temp. of 1,000 and you'll be OK.

Time for dinner!

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein

 

[arunmrao]

Have you tried fast air cooling as your thickness is low.

 

[hillmd92]

Thank you very much for all the help, I think I am on the right track.

The next challenge I am facing is hydrogen embittlement after Rohs Zinc plating.

We have notice a significant decrease in toughness after plating. So far we have tried baking the parts within 4 hours after plating at 375°F for 4 hours but we are still seeing the problem. I assume we need to lengthen the baking time, is there any rules for how long? Is there anything else I should be aware of with 4130?

 

[Metalguy]

Use 24 hr at 375F, but I don't think HE will be a problem after you temper at 1000F min.

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein