Found the following chart from the Internet. I thought it is a good idea to share this piece of information about the selection of Tool Steel with my Blog readers.

This chart comparing the toughness and wear resistance of some common tool steels such as A-2, D-2, L-6, O-1, S-7 and H-13. It provides a guide to the tool designers when comes to selection of correct tool steel.

D-2 tool steel is a high carbon, high chromium tool steel used on applications requiring high wears resistance. D-2 steel can be surface treated such as nitride, titanium nitride if to increase it surface hardness.

O-1 is common oil hardening tool steel that may be hardened from fairly low temperatures with little size change. O-1 can be given standard surface treatments such as hard chrome plating if desired. Nitriding is not generally practical due to a substantial loss of core hardness.

AISI L-6 tool stee is tough, high- strength tool steel that suitable for general purpose applications.

Like wise, L-6 can be given standard surface treatments such as hard chrome plating if desired but not suitable for Nitriding process due to a substantial loss of core hardness.

AISI A-2 tool steel is an air hardening medium alloy tool steel that is heat treatable to HRC 60-62. It has wear resistance intermediate between the oil hardening tool steels ( O-1) and the high carbon chromium tool steels ( D-2) . Because it offers a combination of good toughness along with moderate wear resistance, it has been widely used for many years in variety of cold work applications. A-2 is quite easily machined in the annealed condition and exhibits minimal distortion on hardening, making it an excellent choice for dies of complicated design.

A-2 can be surface treated such as nitriding, titanium nitride coating to further improve it surface harness, hence, improve wear resistance.

S-7 is a shock-resistant air hardening tool steel. It commonly applied for high impact resistance application such as coining, clod forging. It offers good toughness to withstand chipping and breaking, combined with high attainable hardness and good wear resistance.

S7 is not typically suitable for nitriding or similar surface treatments.

H-13 is the most popular and most versatile hot work tool steel that provides a good balance of toughness, heat check resistance, and high temperature strength. It may be used for tool temperatures up to about 1000 F (530 C).

Because of its high tempering temperatures characteristic, H-13can be treated by most surface treating processes, including conventional and ion nitriding, titanium nitriding, and other coatings or treatments to further improve it surface hardness.