What is hardest steel?

Answer 1

By Izod or Charpy impact strength, a widely-published property proportional to [fracture] toughness (which is barely to be found), the toughest metal is some grades of stainless steel (INCOLOY 803 [Fe:Ni:Cr:Al:Ti:C] claims 407 J; Gall-Tough PLUS [Fe:Cr:Ni:Mn:Si:Mo:N] claims 404 J.), then nickel alloy (Haynes Hastelloy B-3 [Ni:Mo:Cr:Fe], 358 J), then titanium (grade 1, 310 J; other grades are 100-200 J), then low-carbon steels (14-339 J).

Answer 2

The hardest steels and even the hardest metals are High speed steels (HSS). High speed steels are characterized by high carbon content (often well above 0.6%) and other additives that help the alloy take a bigger quench and maintain it's strength at high temperatures. In particular high speed steels always have a total of over ten percent of molybdenum and tungsten.

HSS's often also contain cobalt, vanadium and chromium in significant amounts.

Some HSS's such as M42 can even be hardened above a Rockwell C hardness of 70. Meanwhile common steel products will often only be in the 30's which is why HSS tools can be used to cut regular metals. The composition of M42 is as follows (exact percents will vary depending on the manufacturer).

1.1% carbon

3.8% chromium

9.5% molybdenum

1.5% tungsten

1.2% vanadium

8% cobalt

The remainder is iron.

Many sources will list tungsten carbide as the hardest metal but carbides are not classified as metals, they are ceramics. It is true that tungsten carbide is harder than any metal but it is not the hardest carbide if we are going to count them (boron carbide is the hardest carbide).

Answer 3

I'm not sure I understand your question. Iron is a metal, and steel is an iron alloy. But between steel and iron, steel can be considerably harder.

Answer 4

high alloy steel or tool steel