SA 765 Grade II ( Normalize + Temper)
Chintan Raval
abdullah Alhiji
To calculate the soaking time for tempering cycle at 670°C for a 50mm thick SA516 Gr.70 plate, the following steps can be taken:
Determine the required tempering time: The tempering time required for a 50mm thick SA516 Gr.70 plate can be estimated based on empirical data or by referring to industry standards or the manufacturer's recommendations. As a starting point, a tempering time of 2-3 hours is typically recommended for plates of this thickness.
Calculate the heating time: The heating time required to reach the target temperature of 670°C can be calculated based on the plate thickness, the heating rate of the furnace, and the specific heat capacity of the plate material. The heating rate of the furnace can be obtained from the furnace manufacturer or from empirical data. The specific heat capacity of SA516 Gr.70 can be obtained from engineering handbooks or from the material data sheet.
Determine the soaking time: The soaking time is the time required for the entire thickness of the plate to reach the target temperature and to remain at that temperature for the required tempering time. The soaking time can be calculated by subtracting the heating time from the required tempering time.
For example, if a tempering time of 3 hours is required for a 50mm thick SA516 Gr.70 plate, and the heating rate of the furnace is 50°C per hour, the heating time required to reach 670°C would be:
Heating time = Plate thickness / Heating rate Heating time = 50 mm / 50°C per hour Heating time = 1 hour
Subtracting the heating time from the required tempering time gives the soaking time:
Soaking time = Required tempering time - Heating time Soaking time = 3 hours - 1 hour Soaking time = 2 hours
Therefore, the soaking time for a tempering cycle at 670°C for a 50mm thick SA516 Gr.70 plate would be 2 hours.
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P Goswami
Hello Chintan,
Both SA 765 Gr II & SA 516/70 are classified as P1 Gr2 as per Sec-IX. However, if you though between the lines of individual specifications in Sec-II, Pt-A, you’ll notice subtle differences. The differences are with respect to heat treatment and Notch Toughness acceptance criteria. Usually, higher acceptance margins are called for SA 765, Gr II.
If your project specifications call for PWHT @ 670 Deg C that’s too high for any C-Mn steels, say SA 516/70. In my opinion it would be advisable to test SA516/70 base metal first with a simulation heat treatment @ 670 Deg C. The soaking cycle could be as per UCS 56, assuming Sec VIII, DIV1 is the code of construction or the applicable code.
Based on the results it would be the judgement call to qualify PQR on 516/70 steels or not.
The soaking time calculation may be adopted as per the code of construction (DIV-1 o DIV-2).
Thanks.
Pradip Goswami.P.Eng, IWE.
Independent Welding & Metallurgical Engineering Specialist
Consultant: SNC Lavalin Inc. (Nuclear &Non-Nuclear)
Saudi Aramco Approved Designated Project Welding Engineer (DPWR)
Qatar Petroleum Approved, SME-Materials & Corrosion Engineering.
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On Mon, Mar 13, 2023 at 11:52 AM Chintan Raval <chin...@gmail.com> wrote:
Dear Expert,
Kindly advice
for subjected material I want to qualify PQR P1G2 ( normalize) to P1G2 ( normalize + temper) for impact application.
As lead time for forging SA 765 gr 2 is quite high I want to perform tempering on plate SA516 gr 70 (Normalize) to simulate actual condition of N+ T before welding.
Kindly advice soaking time calculation for tempering cycle @ 670 deg cel.
Plate thick 50 mm
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