I have three studs made from 416 stainless steel, consistent with ASTM A582. Two of them have a hardness of ~RB 90 while the third has a hardness of RB 99. Similarly, tensile specimens machined from these three studs have a tensile strength of 87 ksi vs 105 ksi. The two lower strength bolts...
Lots of fragments of the babbitt, some popped out. The fracture surface of the babbit looks like a fatigue surface and there is not a lot of smearing. Metengr made mention in an old posting of babbitt fatigue (see thread605-155979 ) and this sound like what he describes. Can anyone provide...
Anyone have data regarding the depth of the surface damage induced by sand blasting (using sand/slag/oxide, not the more esoteric materials like soda ash, dry ice, or sponge) carbon steel to remove adherent oxide (magnetite)?
Does anyone have actual metallographic images of this type of cracking. I've got a failure analysis I am working on that is not creep related, but someone got it in their head that it is Type IV creep cracking and I would like an image to show how what we have is completely different from what...
I have a 347 stainless steel superheater tube that is sensitized. The microstructure shows the grain boundaries even before I etch due to the really big carbides along them and under the electron microscope some of these carbides are niobium rich and others are chromium rich. No surprise.
The...
I've got a 310 stainless steel sootblower nozzle that failed in service and was found in the bottom ash system some time later. The fracture is intergranular (I'm thinking creep, given that the unit has a history of cooking their sootblower long retracts) on both the outer and inner surfaces...
Does anybody have such a phase diagram? How 'bout zinc + sulfur binary phase diagram? My copy of the Metals Handbook does not have either and I'm looking for temperatures for when things turn to liquid.
I have a threaded stem nut that drives a valve shaft up and down. The threads on the stem nut have been worn to 50% width (estimated). Would I be able to state that the stress in the threads is therefore doubled?
Any thoughts on the manufacturing process for doing this? The wire is drawn to diameter, coiled and then the spring is heat treated. I have a compression spring with a hardness of RC 55 (converted from Vickers) that would suggest a H900 heat treatment if this were a forging/shaft type of...
I have 5/8" diameter barstock, 12" long, that I want to solution heat treat to return it to the fully annealed condition before I run a series of sensitization HT for some experiments. My plan is to soak it at 1900°F for 30 minutes. Any thoughts?
One of the techniques used to deslag a boiler is through the careful use of explosives to remove the slag from the underlying steel tubes. On occassion, there are consequences of this process in the form of damage to the underlying tubes.
If one looks at a carbon steel (or low alloy) with a...
I have a drain line in a base-loaded power plant that failed due to corrosion in the bend. That is, the wall thickness is near original in the straight sections but decreases rather gradually as you move into the bend (from either direction). If I take a hardness measurement of the 2¼Cr-1Mo...
Does anyone have suggestions regarding the possibility of reheat cracking of bolts. I have two that failed by overload when they were torqued, but both have a small (10% of the cross-sectional area) semi-circular region of initiation that is intergranular, oxidized (magnetite, rather than...
Anyone have thoughts on the fatigue behaviour of spheroidized steel would be different than that of a clean ferrite & pearlite microstructure? The material in question is a carbon steel boiler tube that is subject to thermal fatigue cracking. The structure is fully spheroidized (during...
Anybody have any idea what a Co-Cr-Mo alloy would be doing inside a 230/69 kV transformer? The compartment in question has a copper blush of copper and copper-zinc particles over much of the surfaces, but mixed in with this debris are particles of this Co-Cr-Mo material (58Co-31Cr-11Mo). Any...
Assume, for the moment, that you have a piece of low alloy steel that has experienced elevated temperature service to the extent that it has creep damage (random microvoids at the worst - metallography showed no aligned microvoids or microcracks visible). Now take that piece of steel and pull...
My Brackground:
I have a nickel-aluminum-bronze (cast) electrical bolt that contains a tin coating. The casting has a large number of casting voids in it (that resulted in failure when torqued). Examination of the casting porosity shows tin 'flakes' on the surface of the dendrites. I have a...
Does anybody have any thoughts on mitigation of corrosion of an anodized aluminum water jacket? This is a chamber that fits around a metallographic mounting press to cool the mold chamber after the plastic mount is finished "baking". The temperature of the mold is 300°F when the process's...
If I recall correctly, the the Larson-Miller parameter for creep, defined as
P = T(20+log t), where T is abs. Temp & t is hours,
can be used for time/Temperature substitution for heat treating of steels. I have a boiler tube (centerwall, max design metal temp 850 F) that may have experienced...
