best heat treatment to improve impact toughness at -40 ¦C
best heat treatment to improve impact toughness at -40 ¦C
(OP)
Hi everybody
A friend who work on casting part with this composition (according to the ASTM A 148) want to improve the impact toughness at -40 °C ?
Can anyone give us best practices in heat treatment to improve the impact toughness at -40°C
- What is the austenization temperature AC3 + ????
- Can a homogenization before the austenization improve the mechanical properties?
- Can a normalizing before the austenization may be improve the mechanical properties?
- What is the temperature of the tempering ?
- Is a second tempering may improve the impact toughness ?
- How can we adjust the chemical composition to improve the impact toughness at -40 °C
C 0.13
SI 0.52
Mn 1.31
S 0.005
P 0.011
Cr 0.165
Ni 0.70
Mo 0.06
Al 0.05
Cu 0.08
Nb 0.004
V 0.001
Ti 0.003
Sn 0.004
B 0.0005
Thanks in advance
A friend who work on casting part with this composition (according to the ASTM A 148) want to improve the impact toughness at -40 °C ?
Can anyone give us best practices in heat treatment to improve the impact toughness at -40°C
- What is the austenization temperature AC3 + ????
- Can a homogenization before the austenization improve the mechanical properties?
- Can a normalizing before the austenization may be improve the mechanical properties?
- What is the temperature of the tempering ?
- Is a second tempering may improve the impact toughness ?
- How can we adjust the chemical composition to improve the impact toughness at -40 °C
C 0.13
SI 0.52
Mn 1.31
S 0.005
P 0.011
Cr 0.165
Ni 0.70
Mo 0.06
Al 0.05
Cu 0.08
Nb 0.004
V 0.001
Ti 0.003
Sn 0.004
B 0.0005
Thanks in advance





RE: best heat treatment to improve impact toughness at -40 ¦C
The ASTM A 148 specification requires either normalization, normalization and temper or quench and temper heat treatment. Several questions are below based on a review of A 148;
Questions
What heat treatment has your friend performed thus far and what are the impact test results at -40 deg C?
What size casting?
What minimum strength level is necessary for the casting?
What minimum impact value are you looking to achieve at -40 deg C?
Basically, for austenization you need to keep grain size under control. Coarse austenitic grains will result in lower
notch toughness. The quench and temper heat treatment should be the best for notch toughness.
Regarding chemical composition the low carbon content, which you have shown below, is good because this is the main element that affects notch toughness behavior.
RE: best heat treatment to improve impact toughness at -40 ¦C
What heat treatment has your friend performed thus far and what are the impact test results at -40 deg C?
Autenization at 940 °C and tempering at 630-650°C
What size casting?
3250 * 325 * 325 mm bloc test
What minimum strength level is necessary for the casting?
90 Ksi
What minimum impact value are you looking to achieve at -40 deg C?
27 Joules
RE: best heat treatment to improve impact toughness at -40 ¦C
A comparison of the two indicates that your carbon is low 0.13% and Mn high 1.31%. Did your friend achieve R.T mechanical properties with 0.13% C?(90ksi)
Normally even for 148 grades, carbon is maintained at around 0.25-0.28% and Mn around 1-1.1%. Your Ni addition is good,add some Mo 0.2%(it helps,don't ask how or why?)
Once you have adjusted the chemistry, Normalise and double temper the castings,you will get the -40C impact values. Just forgot add some grain refiners like CaSi,mischmetal,ferro silicon zirconium in the melt just before pouring.
If you think education is expensive, try Ignorance.
- Andy McIntyre
_____________________________________
RE: best heat treatment to improve impact toughness at -40 ¦C
The data given by my friend indicated that he tried several compositions
here some examples
RE: best heat treatment to improve impact toughness at -40 ¦C
If you think education is expensive, try Ignorance.
- Andy McIntyre
_____________________________________
RE: best heat treatment to improve impact toughness at -40 ¦C
Thanks but what about the quenching and tempering temperatures ?
RE: best heat treatment to improve impact toughness at -40 ¦C
My experience with heavy section castings is limited,perhaps others might come in soon and share their experience.
Good Night!
If you think education is expensive, try Ignorance.
- Andy McIntyre
_____________________________________
RE: best heat treatment to improve impact toughness at -40 ¦C
RE: best heat treatment to improve impact toughness at -40 ¦C
RE: best heat treatment to improve impact toughness at -40 ¦C
If you think education is expensive, try Ignorance.
- Andy McIntyre
_____________________________________