Does High CE Explain Martensite Formation?
Does High CE Explain Martensite Formation?
(OP)
I understand that high carbon alloys (~ 0.3- 0.4% and greater) require post weld stress relief and thermal treatment because of the likely formation of hard martensite that needs to be tempered and that the ability to form martensite is related to the carbon content.
But what about other chrome molys that have a low carbon content (< 0.15%) but have a high CE value due to high chrome and Moly, i.e., 2.25% Cr & 1%Mo? Is martensite formation still possible with this alloy even though it has low C?
If so, suppose I maintain a high preheat temperature, say 400 deg F? will this be sufficient to slow the cooling rate through the HAZ and prevent formation of martensite?
But what about other chrome molys that have a low carbon content (< 0.15%) but have a high CE value due to high chrome and Moly, i.e., 2.25% Cr & 1%Mo? Is martensite formation still possible with this alloy even though it has low C?
If so, suppose I maintain a high preheat temperature, say 400 deg F? will this be sufficient to slow the cooling rate through the HAZ and prevent formation of martensite?





RE: Does High CE Explain Martensite Formation?
Yes. There is a good article in the recent AWS Welding Journal that explains the correlation with carbon equivalent equation, prehat requirements and hardness (related to formation of martensite). Also here is a web site that shows predicted hardness related to chemical composition;
http://homepage3.nifty.com/yurioka/exp.html
RE: Does High CE Explain Martensite Formation?
Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)
RE: Does High CE Explain Martensite Formation?
Thanks
RE: Does High CE Explain Martensite Formation?
November, 2008
"Estimating Welding Preheat Requirements for Unknown Grades of Carbon and Low Alloy Steel"
by Hinton and Wiswesser
RE: Does High CE Explain Martensite Formation?
Also there are good source of information on the web like this from Steel Matter:
"An increase in Mo content shifts the CCT and TTT curves to the right and also separates the ferrite + pearlite region from the bainite region making the attainment of a bainitic structure more controllable."
http://w
and this
Martensite and Martensitic Phase Transformations
http://
hope this help
S
Corrosion Prevention & Corrosion Control
RE: Does High CE Explain Martensite Formation?
Thanks for the WJ reference, it will be a week before my copy arrives.
I would interpret the "move to the right" will cause slower cooling rates to more readliy result in martensite formation rather than pearlite formation - would this be true?
Arunmrao - what is the significance of "carbon content in the martensite will be of a lower order" ? will this simply mean that whatever martensite is formed that it will be in a less hardened state? or will it mean that overall less martensite will be formed and leave a greater percentage of austenite?
RE: Does High CE Explain Martensite Formation?
Correct.
Lower order I believe would refer to lower hardness. Besides a potent hardener for martensite, carbon is an austenite stabilizer, so increased carbon would tend to increase retained austenite upon quenching.
RE: Does High CE Explain Martensite Formation?
Regards,
Cory
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.
RE: Does High CE Explain Martensite Formation?
Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)
RE: Does High CE Explain Martensite Formation?
RE: Does High CE Explain Martensite Formation?
I produce mandrel casting having C 0.15%, Ni 4.5%, Cr 1.2% and Mo 1.2%. In my ignorance, I removed the feeder heads by oxy acetylene cutting,and then did snag grinding of the surface. These were then annealed and during machining, beautiful cracks appeared on the gas cut surface .
I learnt my lesson of treating low carbon martensite with respect that day .
Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)