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Are there certain types of plastic that we should look for if we have, say, an alkaline cleaner for a passivation cleaning? This thread is suddenly becoming extremely relevant IRL.

I would seriously love to come to this... but I have an audit that week :-(

Didn't mean to offend any QA working in the Chinese Steel industry - just figured the cheap-ass moniker was a quick way to indicate that we're buying this stuff because it's the absolute cheapest we can get. All other things being equal, you get what you pay for in most cases. Polishing and...

The quick breakdown: - 52100 Steel, through-hardened to a martensitic phase for bearings. - Material from other sources with this part # are running fine, but this specific batch of material is growing/shrinking all over the place, going way out of round and out of flat. - Cut and polished a...

So I've been tasked with coming up with controls for a stainless steel passivation line, and one of the requirements is a weekly check of the concentration in a tank of alkali cleaner/degreaser. Our machine operators have digital refractometers that they use to check the concentration of their...

I know this pretty much just echoes redpicker's synopsis, but it's so rare that I actually get to contribute to one of these because I actually have experience in the field. How are the parts processed through heat treat? Are they furnace hardened or induction hardened? Are they hardened one at...

Sorry, was in a rush when I wrote the original. The cracks are in the "root" between the teeth. Material is regular old AISI 4140 H. Quenchant is polymer-based. More info has come to light since this post that has all but defined the problem. I appreciate the help.

Analyzing a very large round gear (~15 feet across) that has teeth case hardened to ~.100-.150 case depth. The teeth are on the inner circumference of the round gear. Induction hardening does an "every other gap" process when case hardening the gear teeth. On the second pass, the areas not...

A decent Q&D test that I have found is to subject the part to a sub-zero cooling cycle (-90 F) for a couple hours, then seeing if the hardness has jumped a couple points from its previous state. If an increase in RHC is seen, chances are there was some retained austenite in the part. (Don't...

So I work for a small bearing company that recently (~6 months ago) got an induction hardener to through harden stainless steel bearing races. Predictably, the faster production rate has the production manager trying to cram anything and everything that they can run into this machine. (The...

I have applied a sub-zero treatment and the hardness only came up about 2 points, so I'm going to guess it's not a retained austenite. If others have had decarb issues with forgings like this it would make more sense with some of the other things I've found out today.

Dear Engineering Hive Mind of the Internets, I currently work for a facility that through-hardens 440c small Bearing Races via Induction Hardening. Recently, a part that was "only soft on one side" was brought to me for analysis. After polishing/microhardness/etch, there is a visibly "shiny"...

Greetings, Background: We currently use an induction hardening process to through-harden very thin (~.25 in) bearing races, normally 440C and polymer quenched. Recently, we have started using this process on our 52100 bearings as well, to limited success. We have seen improvements in our...

Wow, thanks for all the great information! We are in fact deep freezing before any tempering step. The parts in question are in fact round, and have a maximum cross-section of about 1/2." So I would expect to see mostly martensite. As I understand it, the water quenching is mostly so the...

While I have plenty of experience with low-carbon steel microstructures, I have only recently begun working with stainless steel (specifically, 440c.) I have been trying to polish and etch a few samples that based on the heat treatment of the cycle should be mostly martensitic in nature. (Thin...