High-speed steels
When tool steels contain a combination of more than 7% molybdenum, tungsten, and vanadium, and more than 0.60% carbon, they are referred to as high-speed steels. This term describes their ability to cut metals at “high speeds”. Until the 1950s, T-1 with 18% tungsten was the preferred machining steel. The development of controlled atmosphere heat treating furnaces then made it practical and cost effective to substitute part or all the tungsten with molybdenum.
| Grade | C | Cr | Mo | W | V |
|---|---|---|---|---|---|
| T-1 | 0.75 | – | – | 18.0 | 1.1 |
| M-2 | 0.95 | 4.2 | 5.0 | 6.0 | 2.0 |
| M-7 | 1.00 | 3.8 | 8.7 | 1.6 | 2.0 |
| M-42 | 1.10 | 3.8 | 9.5 | 1.5 | 1.2 |
| Defining property | AISI-SAE grade | Significant characteristics |
|---|---|---|
| Water-quenched | W | Molybdenum alloying optional |
| Cold-working | O | Oil-hardening, O6-0.3% molybdenum, cold-work steel used for gauges, cutting tools, woodworking tools and knives |
| A | Air-hardening, low distortion during heat treatment, balance of wear resistance and toughness, all molybdenum alloyed – 0.15-1.8% | |
| D | High carbon, high chromium, 0.9% molybdenum, very high wear resistance but not as tough as lower alloyed steels | |
| Hot-working | H | H1-H19 – chromium base H20-H39 – tungsten base H40-H59 – molybdenum base |
| Plastic moulding | P | Low segregation: reduced alloying of silicon, manganese and chromium Through hardenability: increased molybdenum and vanadium |
| High-speed | T | Tungsten base (today mostly replaced by M22) |
| M | Molybdenum base | |
| Shock resisting | S | Chromium-tungsten, silicon-molybdenum, silicon-manganese alloying, very high impact toughness and relatively low abrasion resistance |
| Special purpose | L | Low alloy, high toughness |
| F | Carbon-tungsten alloying, substantially more wear resistant than W-type tool steel |
Reviews
There are no reviews yet.