Ok. does it change from material to material then? or is there a proper formula?
I was testing Duplex Steel the other day with a measured velocity of .5815
which is between 'Steel, 4150, Rc64' of .582 and Magnesium (O-1) .580.
but the shear velocity has a big jump between the two materials...
We are unable to get a V1 block made out of this kind of steel...
17:50 Jan-27-2009 Michel Couture NDT Inspector, consultant, Canada, Joined Sep 2006 804
Re: ULTRASONICS: Shear/Longitudinal Velocity Calculation...In Reply to Nathan at 14:29 Jan-27-2009 (Opening).
I'm a little curious, so I hope you won't mind if I ask a few questions? Is this Duplex Steel a material that you have to inspect on a regular basis? And why can't you get a block made? The reason I'm asking is because has you know, we should use a Calibration Block of similar material properties to what we are inspecting. ASTM E 164 gives you all the dimensions with tolerances for both a U.S. and Metric block.
I often come across similar situation with one of my client and when this arise, we ask him to make a Calibration Block that will suit our inspection requierement. In our case, it may be a little easier because they also have a very large machine shop that will accomodate our needs.
Re: ULTRASONICS: Shear/Longitudinal Velocity Calculation...In Reply to Michel Couture at 17:50 Jan-27-2009 .
It was more of a theoretical question really.
I got sent to an offshore platform to get some wall thickness readings on some new carbon steel pipework,when I arrived, I noticed it was Duplex Steel D3N450. So I measured a pipework flange with a micrometer, then used this measurment for the velocity calibration on my Epoch LT.
We will only really be checking this piping for internal erosion, so the exact wall thickness is not 'that' important, however, the amount of loss (if there is going to be any) has to be logged. So, as we'll always use the same velocity, we should be able to calculate the loss.
The reason we can't get a V1 block made is that our supplier can only supply in aluminum, carbon steel or duplex.
17:26 Jan-29-2009 Michel Couture NDT Inspector, consultant, Canada, Joined Sep 2006 804
Re: ULTRASONICS: Shear/Longitudinal Velocity Calculation...In Reply to Nathan at 09:20 Jan-28-2009 .
I know where you're coming from. At some occasions, I was in the same situation. I relsove my problem by finding a good reliable machine shop and contracted them to do my calibration pieces. It's true that I didn't really have to deal with exotic metals. At the time, being in the aircraft industry, 2024T3, 7075T6 Al and Ti are readily available in my area.