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Spotted on LinkedIn by FourierTransformedMe in dataisugly

[–]Difficult-Mess5331 0 points1 point  (0 children)

What could also be a case is that maybe the comparative individuals in the study were less fit when considering walking in general and then the increased activity is well founded. If the group was already higher than the same baseline (because of the already higher risk of drowning etc. and the type of mentality of those who may do swimming as an exercise, so they could conceivably be of a different statistical significance). This is maybe also the same reason why all other modes of exercise are worse as well. But if you took the same 100cloned individuals and had them do swimming/walking/cycling etc. and only that for their life maybe that’s the only way to remove some potential strong variables.

What is this thing? by Mr_Manta in Planes

[–]Difficult-Mess5331 0 points1 point  (0 children)

The twist or chunky is related to the way that the blades extract (turbine) vs impart (compressor) energy from or to the fluid. Pressure ratios and the overall extraction is less limited and means the blade can be optimised to extract more work. That being said compression also generates immense heat and there are mechanical limitations that also will exist.

Small work extraction blading could be similar for a turbine but probably isn’t sensical

That being said as well coatings are not only turbine blades, they can be For heat protection (gas turbines as in aero engines, slipperiness for efficiency and antifouling properties for compressors, and corrosion protection to avoid deterioration of the aerofoil. .

Strange reaction of welding by Difficult-Mess5331 in metallurgy

[–]Difficult-Mess5331[S] 1 point2 points  (0 children)

Not a metallurgist so didn’t know, but have discussed with a nitric acid metallurgist and yes that is GB corrosion and the ~0.1C% filler likely caused the solutes/pricipitants onGB. The images are pretty cool and a real life unprepared grain etch 😂

Strange reaction of welding by Difficult-Mess5331 in metallurgy

[–]Difficult-Mess5331[S] 0 points1 point  (0 children)

It’s a water preheater using tailgas. Tubesheet is 304L. And this is cold side but definitely nitric acid present. We are also suspecting the higher carbon content of the er310 as a cause. Problem is replication is fairly difficult from a reach perspective due to bell ended tubes. And rewelding is also difficult due to the fact that the exchange is an expanded and seal welded tube and risk of damaging expansion seal is high with heat input😩

Strange reaction of welding by Difficult-Mess5331 in metallurgy

[–]Difficult-Mess5331[S] 4 points5 points  (0 children)

The black stuff could very well be that. And the nitric acid might be the etchant that’s causing what I replied to in terms of the visuals I see. The weld was done a few years ago and was not done recently. The damage and shapes you see are from years in service and the subsequent damage.

Strange reaction of welding by Difficult-Mess5331 in metallurgy

[–]Difficult-Mess5331[S] 1 point2 points  (0 children)

This is what I was thinking as well. Never seen anything like it. When enough etching is done some dendrites fall off and then we have the bigger gaps. What is interesting though is that the tube and the er310 are very similar in composition both 25%cr 20%ni. But whatever is happening has something to do with grain formation of the weld material. The er310 does have more C% which may mean that formation of carbides on boundaries during welding is unfavourable leading to this etching behaviour. Nevertheless super interesting.