I have a kitchen knife (Japanese type chiefs knife.) that was made in the U.S. by Simco in the 1920's or earlier which makes it now over 100 years old. The blade is not stainless and did turn blue black after cutting onions. I am wondering what kind of steel this knife was made of as I do not think such things as D2 steel even existed back in 1920 so therefore I do not know what kind of steel kitchen knives were generally made of before the big switch over to stainless steels starting after the year 1900.