This may answer your query partially, however The mechanical properties of plates do not only depend on the heat treatment conditions and the plate thickness but also very strong on the applied alloying concept. Depending on the actual requirement on mechanical properties (especially toughness), plate thickness, PWHT condition and maximum allowable CE value that the choice of the optimal alloying concept is necessary to guarantee good quality of the steel plates.
It was also demonstrated that too severe prescriptions in the specifications which only consider certain parts of the influencing factors as e. g. chemical composition or PWHT conditions limits the plate designer´s possibilities to optimize the materials properties. It is therefore recommended that the steel manufacturers involved in the plate design are included at an early stage in the development of the
specifications.
THE HOLLOMON - JAFFE PARAMETER
To describe the effects of a tempering and/or post-weld-heat treatment (PWHT) on the mechanical properties for a various number of steel grades the so called "Hollomon parameter" (HP) is used. By
means of the HP, it is possible to combine all relevant heat treatment parameters such as heating and cooling rate, holding time and -temperature into one value. The concept of the HP-parameter is not applicable in the case of heat treatments in the austenitic range such as heat treatment for hot forming or normalisation. The higher the HP-value, the stronger is the metallurgical effect on the mechanical properties. Especially for CrMo-steels, a strong correlation between HP and yield strength, tensile strength and toughness is discussed in the previous attachment. For a single PWHT, the HP value can be easily determined by the formula which is shown in figure below.
REFERENCES
THE INFLUENCE OF THE ALLOYING CONCEPTS ON MECHANICAL PROPERTIES OF CMn-STEEL GRADES
Dr. Ingo Detemple, Dillinger Hüttenwerke
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Prakash Hegde
Sent: Monday, November 01, 2010 8:17 PM
To: materials-welding@googlegroups.com
Subject: Re: [MW:7997] LM parameters
Thanks for literature of Dillinger on HP parameter
However I want to know how many time we can Normlise (Heat the CS plate above AC3 ) during hot rolling the plate (During hot forming of shell)
with out affecting themechanical properties
Regards
Hegde P.B.
From: Bathula Raghuram (Mumbai - PIPING) <R.Bathula@ticb.com>
To: "materials-welding@googlegroups.com" <materials-welding@googlegroups.com>
Sent: Mon, 1 November, 2010 5:15:53 PM
Subject: RE: [MW:7995] LM parameters
Thou I am not clear with this parameter, attached document might be helpful to you,
HP: You can calculate online @ dillinger.de
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Prakash Hegde
Sent: Monday, November 01, 2010 5:00 PM
To: materials-welding@googlegroups.com
Subject: [MW:7993] LM parameters
Requested to share your view
Regarding --LM parameter /HP parameter
While calculating total equvilalent heat treatment time through LM parameters Do we require to consider Normalising time also ?
Can we apply LM parameter for Normalising cycle also similar to Heat treatment below AC1 temp.
Regards
Hegde P.B.
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