Characterized by their durability, hardness, price, and ability to withstand shock without deforming, tool steels are used to cut, press, extrude, or stamp other metals. After being worked, they may be hardened to increase wear resistance and strength. Grades are specified by the American Iron and Steel Institutde (AISI), the Society of Automotive Engineers (SAE), or the American Society for Testing and Materials (ASTM).

Design Considerations

Tool Steel Grades

Tool steels are defined by their dimensional stability, wear resistance, toughness, hot hardness, and machinability. Severe conditions – high temperatures, heavy loads, or corrosive environments – require higher alloy and carbon contents.

How Standards Help Manufacturers

In the manufacturing industry, standards establish a common set of requirements to ensure conformity of products across all vendors. This eliminates trade borders, creates uniformity in production. Standards can also increase operational efficiency due to a strong focus on process that contributes to a reduction in production costs.

Cold Work Steels

Frequently used for making cold working tools for applications under 200°C (392°F). Higher amounts of chromium reduce distortion during heat treatment. Feature high hardenability, high toughness, and high abrasion, impact, and wear resistances.

A2-A10, Air-Hardening

Medium alloy composition with 1% – 6% carbon and up to 5% chromium. Has the least tendency to crack during hardening. Considered a mid‑range grade between oil‑hardening and shock resistant grades. Do not quench in oil or water.

01‑07, Oil‑Hardening

A low alloy/high carbon (0.85% – 1.55%) steel with manganese, chromium, and molybdenum. Quenched in oil to produce high wear resistance and hardness between HRC 56‑62.

D2‑D7, High Carbon, High Chromium

Contain 1.4% – 2.3% carbon and 12% – 14% chromium along with molybdenum, cobalt, and vanadium. Often thought of as stainless or semi‑stainless, but corrosion resistance is limited due to high chromium and carbon. Wear resistant, but not as tough as low alloy steels.

Hot Work Steels

Feature high hot yield strength, toughness, high red‑hardness, wear resistance, erosion resistance, and resistance to softening in temperatures up to 675°C (1,247°F).

H1‑H19

Medium carbon content with 5% chromium. Can be through hardened to HRC 40‑55 with little distortion. Requires oil quenching.

H20‑H26

Low carbon content with 9% – 18% tungsten and 3% – 4% chromium. Extra resistant to softening, more prone to brittleness, working hardness to HRC 45‑55. To minimize scaling, quench in oil or salt.

H41‑H43

Low carbon content with 8% molybdenum along with chromium, tungsten, and vanadium.

Water-Hardening Steels

W1‑W3

Most common. These general purpose, low‑cost, medium to high carbon (0.60% – 1.3%) steels are easily machined, or formed. They can be case hardened by heat treating up to HRC 68. Overall, they are more brittle and more susceptible to cracking or warping than other steels. Best suited for small parts and working conditions up to 150°C (302°F).

High-Speed Steels (HSS)

Designed for high speed metal cutting and machining operations. Features hardenability to HRC 60‑70, high heat resistance for red‑hardness up to 500°C (932°F) enables sharpening without damaging material, and reasonable toughness.

M1‑M47

Contain molybdenum as a primary alloying element that increases resistance to softening at elevated temperatures.

Shock-Resistant Steels

S1‑S7

Contain medium carbon content from 0.40% – 0.55%, 1% – 2% silicon, or up to 3% nickel. As their name suggests, they have good wear/abrasion resistance and resist shock at low to medium temperatures, with high strength and toughness. Can achieve HRC 58‑60.

Tool Steel Types

Quick Reference Guide

Common Names:
Tool Steel, Ground Flat Stock, Flat Bar Stock, Flat Stock, Gauge Plate

Applicable Standards:
AISI/SAE A2, AISI/SAE D2, AISI/SAE O2, AISI/SAE W2

Fabrication:
Cold drawn, annealed bar stock that is subsequently ground to remove all traces of decarburization and achieve precision height and width.

How to Identify:
Tight tolerances and ground surface finish. Durable and resistant to abrasion.

Common Uses:
Depending on grade, ground stock can be used as dies, punches, templates, and stripper plates.

Comments:
Ground stock is free from decarburization.

Common Names:
Drill Rod

Applicable Standards:
AISI/SAE A2, AISI/SAE D2, AISI/SAE O2, AISI/SAE H13, AISI/SAE W2

Fabrication:
Cold drawn, annealed round stock that is ground and polished to achieve exacting size with no decarburization left on the bars.

How to Identify:
Tight tolerances and ground surface finish. Durable and resistant to abrasion.

Common Uses:
Drill rod, depending on grade, is used to make tools like drill bits, taps, dowel pins, and hammers.

Comments:
Drill rod is free from decarburization.