JoeWilson
Mame
Most good tool producers will tell you what steel is used. But with stainless, it can be a bit murky; sometimes, only "stainless" will be specified, and this can mean a dozen different types of steel. So I would try to stick to manufacturers who tell you what the steel is. If you see something like "Hitachi/Yasugi high-carbon stainless steel" this is likely one of two steels, ginsan aka silver paper steel, or SLD. For brand new tools, SLD seems more common. If you find older stock somewhere, it might be ginsan (I spend a lot of time on the Japanese auction sites, where it's more common). SLD is a variant of D2, which is a cold die tool steel, so it's something like a mid-point between simple high-carbon steel and HSS - a tool steel meant to cut other metals, but not at high speeds.
As to which steels are more brittle, easier to chip, etc, this can get pretty complex and usually depends on how well they are heat-treated. That said, high-carbon steels, especially Hitachi white steel, which is the most common steel used for Japanese tools, are typically considered brittle. That's one of the reasons that a softer backing steel or iron is used in the typical Japanese laminated construction. The soft steel (jigane) helps to add toughness to the tool, which the hard, brittle steel (hagane) lacks. By a skilled blacksmith, white paper steel #1 (the purest variety) can be forged in such a way that it is hard (63-65 hrc), can get extremely sharp, is relatively easy to sharpen, and is quite durable. But the range for forging and properly heat-treating white steel #1 is quite small and difficult to hit; really only the master blacksmiths, most of whom are no longer with us, were able to do it consistently. You can still buy white #1 tools, but if they were made in the last decade or two, chances are the heat-treatment is dubious, and they may be very brittle and chippy. When it comes to woodworking chisels, you can usually grind back the first 1/8" of the blade and find more stable steel. With scissors, this is impractical, though. So if you want good, traditional high-carbon Japanese tools, I would recommend trying to find vintage ones from the 70s-80s or so, when all those great blacksmiths were in their prime.
Anyway, most inexpensive, high-carbon Japanese tools you can easily find from US retailers (for example, Wazakura) use cheap steel like S58C or S55C, which are not great tool steels and will be somewhat brittle and prone to chipping while having poor edge retention and rust resistance. The main thing these have going for them is you can get them in 2 days on Amazon Prime, otherwise...
Usually, the problem with (cheap) stainless is not that it's brittle, but that it's soft and won't take or hold an edge. In terms of brittleness, Ginsan is the closest stainless steel to the traditional high-carbon Hitachi Japanese steels, so you can expect it to be moderately brittle. I haven't personally noticed ginsan being more brittle than white steel, for example. But I would treat it like a standard high-carbon steel. Don't push it too hard or try to cut thick branches with it, and don't cut anything dirty, sandy, or abrasive.
More modern or higher-end stainless steels are often tougher and less likely to chip than simple carbon steels (steels with only iron and carbon). Modern stainless steels use a combination of alloys to increase the toughness, edge retention, and rust resistance, producing steel that is better in most ways than high-carbon steel. The only real drawback to using modern alloyed stainless steels is that they tend to take longer to sharpen. However, scissors are usually pretty fast to sharpen, and if the steel holds an edge longer, you don't need to sharpen as often. The difference is more evident in other cases, for example, if you have a kitchen knife you need to thin (grind back significantly), that's where you'll feel it. But unless you're reprofiling your scissors or grinding back huge chips, you shouldn't notice it. Even the high-end stainless steels are usually only a little harder to sharpen than high-carbon, a couple of notches below the pain that HSS can be. Good stainless steel is typically more expensive, too, but you get what you pay for.
Most people have an allergic reaction to stainless steel because they've used cheap knives made with 410 or some similarly garbage steel. This stuff is butter-soft (literally only good for butter knives) and can not hold an edge to save its life. 420 is better, but it is still an entry level steel. When we get up to 440b/c or so, this is where decent stainless tool steel starts. Tianbonsai's "Master Craftsman" series uses 9Cr25, which is roughly equivalent to 440, but made in China rather than Japan. SLD should be better than 440. If you want better than that, you get into various exotic alloyed stainless steels like colbalt-infused ATS-314, which is more common in hairdressing scissors. And super stainless steels like CPM-Magnacut and various forms of HSS, which are more difficult to find in scissors form.
If you want to go on a deeper dive, have a look at: https://knifesteelnerds.com/2021/10...ness-edge-retention-and-corrosion-resistance/
Specifically, if you want to know which steels can hold an edge for a long time, look at this chart:
The simple high-carbon steels are towards the bottom, and as you go up, you get into HSS and various forms of quality stainless steels. They don't have white steel on here, but you can see Hitachi Blue Super around 340, roughly on par with 420 stainless, and A8 is in that range too. Then 440C is up a notch higher than that, and D2, which should perform similarly to SLD, is a notch further up, near M2, the most common type of HSS. ATS-314 should be somewhere around here, too, being something like an improved version of VG10. Things get kind of crazy above that, but it's not relevant unless you're willing to spend hundreds (or thousands) of dollars on hairdressing scissors.
I've been putting together a list to keep track of some of the popular or easy-to-find brands in the US. This isn't exhaustive or complete, but should give you an idea. Some of the hardness figures here are estimated based on the working range for these steels, while others are from the manufacturer's specs.
