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bzcc
Participant

Join Date: Jan 2010
Posts: 4

Tensile Fracture Behavior on Tempered Steel

01/20/2010 10:06 AM

i already done by using AISI1040 medium carbon steel... 1stly i heating 14 specimens in a furnace to austenitizing temperature 870 C for 1/2 hour. Then quenching in oil quenching medium..after that i re-heat the specimen for tempering process one by one because i want to make comparison at different tempering temperature but in same tempering time..Tempering temperature start at 100 C,150 C, 200 C,250 C....until 750 C.. but tempering time is same which is 1 hour.

Then the problem is why when i do tensile test, the maximum load is increases. The 1st specimen max load is 50.Mpa..2nd is 100..Mpa.3rd is 147Mpa and so on..and for your info UTM machine is only can do till 250Mpa and i have to stop the experiment due to this case..my question is why the max load increase when the tempering temperature is increase..it is suppose max load decrease while tempering temperature increase...tempering suppose reduced the hardness and increase ductility but why i get those result...plss help me..
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nick name
Guru

Join Date: Mar 2007
Location: City of Light
Posts: 3943
Good Answers: 183
#1

Re: Tensile Fracture Behavior on Tempered Steel

01/21/2010 7:03 AM

Have you thought about internal strains due to quenching?

May be they are released progressively by the tempering and then a higher external stress is required for fracture.
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crstn
Associate

Join Date: Aug 2009
Posts: 25
Good Answers: 1
#2
In reply to #1

Re: Tensile Fracture Behavior on Tempered Steel

01/21/2010 8:26 AM

I subscribe to what nick name said. It seams reasonable.

However I would like to know if you have collected data regarding elongation at the same stress value, versus different tempering temperatures?
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bzcc
Participant

Join Date: Jan 2010
Posts: 4
#5
In reply to #2

Re: Tensile Fracture Behavior on Tempered Steel

01/21/2010 3:14 PM

tq for reply...but i want to know maximum load when i do the tensile test on tempered steel it is suppose increase or decrease while tempering temperature is increase???
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Anonymous Poster
#3

Re: Tensile Fracture Behavior on Tempered Steel

01/21/2010 10:21 AM

1040 is a very shallow hardening steel and oil is a relatively slow quench. You don't say what thickness your test specimens are or what shape (round, flat, or complex) , but it seems likely they are not through-hardening to start with. As suggested above, the tempering could be relieving internal stresses.
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bzcc
Participant

Join Date: Jan 2010
Posts: 4
#4
In reply to #3

Re: Tensile Fracture Behavior on Tempered Steel

01/21/2010 3:10 PM

tq for reply..for your info i`m using round bar gage length diameter is 12.7mm..i want to know the maximum load when apply tensile test to this tempered specimen, it is suppose increase or decrease wile tempering temperature is increase??????????/
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