Dear Sirs,
I am working in closed-die steel forging company. Nowadays, we have problem about the production of connection rod
Details are as follows:
Forging Equipment: 6300 mkg Lasco Counterblow hammer
Raw Mateial: SAE 4140
Forging Temperature:~ 950-1000 C 1st question: What must be the hardnees value as forged in air cooled condition?
For the heat treatment,
First, the part was austenized at about ~880 C during 40 minutes and quenched in 90 C oil bath.
Then tempering was performed at about ~ 550 C during 1 hour. After heat treatment;
Surface Hardness was 34 HRC => This is OK
We have cut a tensile test sample from the body of the part as being perpendicular to the forging direction.The section that we have taken test sample was 20 mm and the diameter of the gage length region after turning was 10 mm. When we performed tensile testing;
Tensile Strength was 1100 MPa => This is OK( the range of this value must be between 1000 to 1150 MPa)
Yield Strength was 513 MPA=> This is not OK. This value must be greater than 650 MPa 2nd question :Can anyone has a suggestion to provide yield strength greater than 650 MPa without causing deviation of tensile strength from the tolerance range 1000 to 1150 MPa ?
Attached the picture of finished connecting rod and drawing of tensile test specimen are available.
Thanks for your assist in advance.
Regards,
Schmieden
