Highly alloyed tool steels — tungsten, molybdenum, vanadium, chromium and often cobalt — that stay hard at the red heat a cutting edge reaches in fast machining. High speed steel is the material of drills, taps, end mills, broaches and saw blades, and of punches that need more wear resistance than cold-work steel gives.
Also called
HSS
HSS-Co
HSS-E
M2
M35
M42
T1
HS6-5-2
1.3343
PM HSS
Powder metallurgy high speed steel
AR
صلب السرعات العالية
ZH
高速工具钢
DE
Schnellarbeitsstahl
FR
Acier rapide
ES
Acero rápido
IT
Acciaio rapido
TR
Yüksek hız çeliği
RU
Быстрорежущая сталь
Main formsRound bars, flats, ground drill rod, tool bits, strip for saw blades, wire
Typical sizesRounds 1–250 mm; flats and squares; tool bits 4–25 mm square
Main standardsISO 4957, ASTM A600, JIS G4403, GB/T 9943, GOST 19265
Typical usesDrills, taps, end mills, reamers, broaches, hacksaw and bandsaw teeth, punches, form tools
Overview
High speed steels contain large amounts of carbide-forming elements: tungsten and molybdenum (together around 10–20%), vanadium (1–5%), about 4% chromium, and in the cobalt grades 5–10% cobalt. After hardening from close to the melting point and tempering two or three times, they reach 63–67 HRC and — the property that names them — keep that hardness up to about 600 °C, so a tool can cut much faster than a carbon-steel one before the edge softens.
There are two families. Tungsten grades (T1, 18-4-1) were the original; molybdenum grades such as M2 replaced most of them because molybdenum does the same work at about half the weight. Cobalt grades (M35, M42) add hot hardness for difficult materials such as stainless steel and titanium. Powder-metallurgy HSS, made by atomising the melt and consolidating the powder, has a very fine, even carbide distribution and is used where conventional HSS chips or wears too fast.
Each grade has three names in use: the AISI letter (M2), the Werkstoff number (1.3343) and the ISO composition code (HS6-5-2, giving W-Mo-V, with cobalt as a fourth figure). Tool catalogues mark HSS as HSS, HSS-E or HSS-Co for cobalt grades and HSS-PM for powder grades.
In the Middle East high speed steel is bought mostly as finished cutting tools; bar and flat stock is imported by tool-steel stockists for regrinding shops, punch makers and the tooling departments of fabrication and oil-tool plants.
Forms & sizes
Round bars
Annealed, black or peeled, and centreless-ground drill rod in h8–h9
Flats and squares
For form tools, punches and knives
Tool bits
Hardened and ground square and rectangular blanks for lathe tools
Strip and wire
Edge material for bimetal saw blades, welded to a spring-steel back
Delivery condition
Soft annealed (about 240–300 HB); the user hardens after machining
