increasing tensile strengthn of 4140 steel shaft 7ft

[jawdayub1]

Hello,

I'm looking to build olympic barbell, i have purchased 4140 grade in annealed form which typical hardness is around 20HRC. I have done knurling on the shaft but i need to increase the tensile strength. the typical tempering and hardness seems to be very expensive to meet the tensile requirements i need it at 205,000PSI. Can i do induction hardness instead? Does induction hardness increase the tensile strength of the bar. We don't have shot peen equipment where i live. How should i meet the UTS with minimum cost?

 

and rusting should NEVER be an issue!

Always keep in mind, the 'stainless' part of 'stainless steel' originated with the marketing department, not the laboratory

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[EdStainless]

yes IM, human sweat is one of the most aggressive fluid out there.
That is why these bars usually have thin Cr plated sleeves over them. Easy to replace and any damage does not compromise the strength of the bar.

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P.E. Metallurgy, consulting work welcomed

 

[jawdayub1]

ah i guess i have no choice but to do through hardening, which seems way too costly? How does rogue fitness and kabuki strength does, there bars don't cost a lot and other brands swell. Do they import from china for large batch manufacturing? Can i buy the bars at 35-40HRC and do the knurling after ?

 

[mfgenggear]

Jawdayub1

check out frysteel bar Normalize and tempered

https://www.frysteel.com/MeetTheMetals/showmetal.php?metal=aircraft##

 

[Martinos]

Hi, jawdayub1, definitely you can buy the bars at 35-40 HRC and do the knurling after. It is very common (and effective) to buy prehardened bars and do machining operations after. QT condition 35 - 40 HRC is not such a terrific regarding machinability, but yes, it is not machinability level like for some free machining shit with tenths of sulphur and lead, or soft annealed ona.

 

Knurling is not a lot of machining, so pre-hardened sounds like the best way to go for a one-off

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[jawdayub1]

40HRC seems to be good idea, hopefully i don't need any special knurling tools and kits for these. Getting pre-hardened seems to be better solution than doing them after will be much costly compare to get it hardened straight from the mill.