500pcs/Set M3 Black Zinc-Plated Carbon Steel Pan Head Self Tapping Screws, Assortment Drilling Screws with Storage Case, 6mm 8mm 10mm 12mm 16mm 18mm 20mm

At least I think they're zinc. Some metal softer than iron/steel at least. Here's a sample from my amazon order history. https://www.amazon.com/dp/B07DLWSQD5 They say zinc-plated steel, but I am not sure that's truthful. All of the really terrible screws I've had at least have all been black. Not that all black ones are terrible, but I haven't had terrible silver ones.