[MW:6427] Re: Ductile to Brittle Transition Temperature

DBTT is the temperature at which the fracture surface of charpy-V
impact test samples turns in to brittle and the values drop down.
For determining this temperature you need a lot of charpy specimens
from the same material or weld sample.
You first start to test single specimens at different temperatures
(which temperature depends on the material) in order to find the
temperature range where you need to execute the test and to reduce the
number of specimens needed.
For example for carbon steel you may test a specimen at 0, -40 and -
80 °C. If the specimen at -40 °C already shows a full brittle fracture
surface without any lateral expansion, and at 0 °C the fracture
surface consist both brittle and tough parts it's sure that the DBTT
lays in between these temperatures.
From this point on you need to test sets of 3 specimens, in this case
at for example +20, +10, 0, -10, -20, -30°C. All these values you can
put in a diagram (Impact value against temperature) and will give you
a curve showing a line from 100% brittle fracture to 100% tough
fracture. You will see that you have a specific temperature where the
values drop from constant high values to constant low values.
To determine the exact DBTT you first need to specify this DBTT. Some
specifications say it should be the temperature half way between 100%
tough and 100% brittle, other specifications specify a minimum charpy
value for the DBTT.

The Drop Weight tear test is a test method similar to charpy impact
testing but at which full thickness samples will be tested against
standard 10x10 mm samples for charpy tests.

Hope this answers your question.

Best Regards,

Herman Pieper

On 10 aug, 17:21, limesh M <limes...@gmail.com> wrote:
> Dear All ,
>
> What is DBTT(Ductile to brittle transition temperature)?
>
> How we can find DBTT?
> Is there any relationship between DBTT and Drop weight tear test?
>
> Regards,
>
> Limesh

--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding-unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.