Trying to estimate the DBTT temperature for A572 & RHA steel based on alloying composition.
Dear Varun:
Without prior exoerimental data on this particular steel, I would maintain that it is practically impossible to accurately predict the DBTT for any low carbon steel. The DBTT will depend on its composition of course, but also on its microstructure and prior heat treatment. The DBTT, however, is extremely sensitive to any small amounts of impurities, such as S and P. The best low carbon steels, with the lowest DBTT, invariably have very low content of these impurity elements (this is termed "aircraft quality" in many higher strength steels). My advice to you is to experimentally measure the DBTT using such simple tests as Charpy impact tests; relying on any predictions or estimates would be highly questionable.
ROR
1.There are several empirical equations that can be used to estimate the DBTT of low carbon steels based on their chemical composition. One commonly used equation is the Pickering-Gladman equation:
DBTT (°C) = 10 + 560C + 80Mn + 20Si + 20P + 10Cr
Where the elemental concentrations are in weight percent (wt%).
This equation provides a rough estimate of the DBTT based on the chemical composition. More advanced models may include additional factors or use different coefficients for specific steel grades.
2.Consult reference data or databases:Look for published data or models specific to the A572/RHA steel grade that you are interested in. Material handbooks, technical reports, or relevant journal articles may provide more accurate DBTT prediction methods for these steels. Online databases or steel property calculators may also offer tools to estimate the DBTT based on the chemical composition and other parameters.
3.Understand the key factors influencing DBTT:The main alloying elements that affect the DBTT of low carbon steels are carbon (C), manganese (Mn), silicon (Si), and sulfur (S). Other factors, such as grain size, cooling rate, and heat treatment, can also influence the DBTT.
EVALUATION OF THE DUCTILE-TO-BRITTLE TRANSITION TEMPERATURE IN STEEL LOW CARBON
Personally I wouldn't trust these empirical approaches. They really are very rough estimates. If the application of the steel is a critical one, I would still insist that an experimental measurement is mandatory.
ROR
Nageswara Rao could you give me the reference for the equation you mentioned, I tried searching online but I can't find it. If you could provide the reference it would be a great help.
Hello Dear Varun
I found The Pickering-Gladman equation for estimating the Ductile-Brittle Transition Temperature (DBTT) of low carbon steels is commonly referenced in the literature.
The original source of this equation appears to be the following publication:
Reference:
Pickering, F. B., & Gladman, T. (1963). Metallurgical developments in carbon steels (Vol. 15, p. 109). Specialist Report, Iron and Steel Institute.
In this publication, Pickering and Gladman presented an empirical equation to estimate the DBTT of low carbon steels based on their chemical composition.
thank you Nageswara Rao but I'm not able to find that literature online. If you have the PDF version would you be able to sent me.
Estimating or predicting the Ductile-to-Brittle Transition Temperature (DBTT) for low carbon steel, such as A572 or RHA, based on chemical composition involves considering several factors. DBTT is the temperature below which the steel transitions from ductile to brittle behavior. For low carbon steels, this transition can be influenced by alloying elements, grain size, and other factors.
Here’s a general approach to estimate the DBTT based on chemical composition:
1. **Identify Alloying Elements**: For low carbon steels, the key alloying elements that influence DBTT are:
- **Carbon (C)**: Generally, higher carbon content increases the DBTT.
- **Manganese (Mn)**: Manganese can improve toughness and lower the DBTT.
- **Phosphorus (P)**: Phosphorus increases the DBTT as it promotes brittle behavior.
- **Sulfur (S)**: Sulfur also increases DBTT by forming sulfide inclusions that impair ductility.
2. **Quantify Composition**: Obtain the exact chemical composition of the steel. Typical compositions for low carbon steels include:
- Carbon (C): ~0.2% to 0.3%
- Manganese (Mn): ~0.7% to 1.2%
- Phosphorus (P):
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