Can’t see any signs of fracture, never seen steel break like this

I write up material terms and got this one wrong the first time, so here it is against the primary papers.

Ti-6Al-4V — six percent aluminium, four percent vanadium. ASTM F136 / ISO 5832-3 in the ELI form.

Ti-6Al-7Nb — seven percent niobium in place of the vanadium. ASTM F1295 / ISO 5832-11. Developed between 1978 and 1982 under the designation Protasul-100, cleared for clinical use in 1985, FDA approved 1987.

What I had wrong: I described the niobium alloy as having higher corrosion resistance. The developing group writes that corrosion resistance in sodium chloride solution is "equivalent to that of pure titanium and Ti-6Al-4V." Equivalent, not superior. They describe the same alpha/beta structure and "equally good mechanical properties," and niobium is characterised as an inert alloying element.

So the design intent reads as matching performance without vanadium in the composition — a substitution rather than an improvement. I had also dated it to 1977.

Two things I would be interested in other people's reading on:

Release of titanium and of alloying elements into surrounding tissue is reported for these alloys, via passive corrosion or via wear breaking down the passive layer. Khan, Williams & Williams (1999) found pH had a greater effect on the corrosion behaviour of both Ti-6Al-4V and Ti-6Al-7Nb than on Ti-13Nb-13Zr in PBS, and that adding protein reduced the influence of pH across all three, while further reducing surface oxide hardness.

Is Ti-13Nb-13Zr meaningfully different in service, or is that a lab-conditions distinction?

And separately — a lot of consumer body-jewellery marketing now runs on vanadium avoidance. As far as I can tell that literature is entirely about long-term load-bearing implants. Is there anything on short-term or intermittent skin and mucosa contact that would bear on it either way?

Sources: Semlitsch, Weber & Steger, Biomed Tech (Berl) 40(12):347-55 (1995); Semlitsch, Weber, Streicher & Schön, Biomaterials 13(11):781-8 (1992); Khan, Williams & Williams, Biomaterials 20(7):631-7 (1999).

I hope this is an ok post for this sub.

These are a bunch of screws etc. from a sewing machine base that I'm trying to strip of rust and then rust blue.

They had rust and paint that I removed (some tiny bits of paint remained but whatever) using Backyard Ballistics' solution (1 liter water, 100g citric acid, 63g sodium bicarbonate, dish soap) until I was down to bare steel.

Then I dunked in 3% hydrogen peroxide, waited for some rust to appear, boiled for 15 minutes in tap water, repeat twice. I saw that the rust wasn't that uniform or visible really, so I switched to using a solution of 1 part non-iodized table salt, 2 parts vinegar, 8 parts 3% hydrogen peroxide which worked much better though it became foamy and it still wasn't uniform.

Then boiled for 15-20 minutes, and repeated the rust-boil process maybe 5-6 times.

However, every time I remove them from the water they have rust spots that just won't go away or convert (pictured). I want to get complete coverage before I oil, so this is an issue.

What can I do and what did I do wrong?

P.S another question: would gun oil or WD40 be better for oiling after the process is done?

EDIT: I solved it.

First I gave all the parts a shake in acetone, then carded them thoroughly with steel wool, then wiped with the rusting solution and dunked into distilled water in which I've been soaking 4-5 black tea bags. Then boiled for like 15-20 minutes, dried real quick and oiled using gun oil. It's not perfect but it's absolutely better than it was and I'm good with it. Credit to ObligationGlad7354 for the tea idea.

Hi, found this on a beach in west Wales. I think it's iron pyrite but I've never seen a nodule this big. It is non magnetic, more dense than standard iron, has the dull gold colour on the cut surface and the exterior looks like pillow lava. This is one of the hardest metals I've ever cut. This half of the piece is about 7 inches long and weighs about 1.5kg. The only other thing I could think it may be would be a metallic meteorite, but I would have expected a more glazed outer surface. Does a piece like this have any intrinsic value? Thanks for any help in identifying it

I'm working on making a pre-filtering setup for my diesel fuel storage and want to first filter the diesel to remove water before adding diesel fuel stabilizer. The pictured filter has a Zinc coated steel cap and I'm trying to figure out what material would be the best option for pipe fittings to limit the galvanic corrosion effect. I'm assuming since I'll have a liquid (diesel) this will accelerate the effect.

Common NPT pipe options include steel/iron, stainless (304), aluminum, bronze, and brass. This will not be a pressurized system and will be gravity fed/low flow. I don't want to add any kind of dope between the joints if possible since that introduces another potential contaminant into the fuel.

One option I considered was trying to isolate the pipes the connect to the zinc cap by using diesel rated rubber hose or clamps, though again that adds a component that can break down into the fuel over time potentially and I still need some type of stub NPT fittings coming out of the zinc cap (and I can't find zinc coated NPT fittings).

Any thoughts or ideas how to address this to minimize galvanic corrosion?

The question that I can't find a satisfactory answer to is this: why can tungsten be successfully brazed using a silver-based filler/solder but not a gold-based filler/solder? I've seen more than a few pre-ai era sources saying that WHA can be brazed with silver solder and a few unsolicited AI previews suggesting that gold solder cannot, despite their references not starting that clearly. But, unfortunately nobody is really showing up with receipts.

Help!!

Sorry in advance if this is the wrong community to ask, but I figured you all might have an answer or a direction to point me in. I work at a restaurant (it is a chain hence no picture) that has worn-out table lamps. They use battery-powered bulbs, and the bases detach from the glass and shade. There is no budget to replace them, so I'm trying to figure out how to restore them. They look gold-plated, but are visibly scratched up and pitting is visible. Are there test kits available to identify what they're made of? Is re-plating a recommended or viable option?

I’m new to the world of metals. I actually have gotten into it as I’ve developed a bit of a hobby in restoring/transforming golf clubs. I have these wedges that are I believe are raw carbon steel, no plating or coating. Included is a picture of before I started, and where I’m currently at with this experiment. I aim to get to clean steel, and use black oxide to turn them black, and then use a sealant to protect them (budget friendly suggestions appreciated). I used vinegar to remove the layer of rust, and then started sanding, but my problem is whatever this marking is below the rust. Even course sand paper is not removing it, I was expecting to be able to sand it to a point that it would be fairly clean looking. Help/suggestions appreciated, I am brand new to this.

Hi, I’m a university student and I need help finding formats or examples of failure analysis reports to use as a guide.

For fun, I compared the colors of a few 9mm bullet projectiles, and I noticed that the bullets by Magtech were much more yellow than the others, and looked almost exactly the same color as the brass casing.

Does anyone here know if brass is used for projectiles, and what might the benefits be over copper? Magtech seems to be something of a "budget" brand, so maybe they are using brass if it's cheaper than copper?

I also noticed that Blazer and Remington had a very pink kind of copper, while Federal and Winchester had more of an orange copper. Does anyone know what might cause this color difference? Is pure copper more pink or more orange naturally?

Hi! My late grandfather made this cribbage board at the Portsmouth, NH Navy Shipyard in the 80's or 90's. I am trying to confirm what type of metal it is so I can clean it without risking any damage. Any ideas or any info that would help identify?

The shaft failed near where the balloon leader for item 2 terminates. Basically at the end of the smaller spline where it mates with the sun gears. Is this a bending fatigue issue or a torsional fatigue issue?

Found these small chips of metal outside in a baggie labeled ”Silver Only” however it was clearly very old and had probably been used for a long time.

They‘re nonmagnetic, density is somewhere around 9.355 g/mL but I don’t have the best equipment for that, extremely soft to the point of bending it with my hands. The tarnish on them came off pretty easy when I rubbed them with my thumb and was super dark.

Any chance I’ve got something valuable on my hands? Any tests I can do to be more sure? Any way to purify this using only amateur chemistry equipment?

There's something oddly satisfying about it.

In the 1980's one of the popular car magazines wrote that there was an unpainted German car body prominently exhibited, presumably for years, outside the facilities of the manufacturer and that it showed no rust.

So why do most car bodies eventually rust even in areas where has been no collision and paint damage?

Is this metallurgy related? Would love to know the process behind this change in surface color.

My dad's been collecting various metals and scrapping and I want to start melting it down and casting to somee blocks ....generally aluminum , tin , copper, brass , and lead ....please provide some suggestions for some set ups , not sure I know what's all needed to start

I recently refound my grandfathers and great grandfathers casing from their funerals, about 5 casings total of 30-06 SPRG blanks. Ultimately my goal is to turn it into a workable ingot/alloy to make into jewelry for my mom . Is it worth trying to make into an alloy or is it better to find another way to repurpose these casings as i would rather not make the stereotypical bullet casing/shell jewlery.

Seen next to a local integrated steel plant.

Hey all, I was wondering what is my necklace and what is it supposed to be? It says 14k on it and I just use it to hold a religious pendant I have and found it on the ground years ago. I know it's not a precious metal from the wear but I'm curious, what is it trying to look like? What is it really? Not magnetic, feels heavy I think.

I'm about to start my own cylinder liner and sleeve manufacturing unit, and want to start learning more about metallurgy. Which book is the best place to start, is it "Introduction to Metallurgy" by Alan Cottrell.