T1

Data verified

T1 is the original 18-4-1 tungsten high-speed steel from which the whole HSS family descends. It remains in use for lathe tools and cutters in shops worldwide, and as China’s W18Cr4V and Japan’s SKH2.

Hardness62–65 HRC

DIN1.3355

AISIT1

JISSKH2

CategoryTool Steel

Chemical composition

Element	Content (%)
C	0.65–0.80
Si	≤0.40
Mn	≤0.40
Cr	3.75–4.50
W	17.25–18.75
V	0.90–1.30

Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.

Properties

Delivery condition	Annealed
Hardness (hardened)	62–65 HRC
Density	8.60 g/cm³
Red hardness	The original 18-4-1 benchmark

Heat treatment

Preheat 850 °C; harden 1260–1300 °C (the hottest of the common HSS); triple temper 540–580 °C.

Equivalent grades

Standard	Designation
din	1.3355
aisi	T1
jis	SKH2
gb	W18Cr4V

Compare side by side: T1 vs T4 · T1 vs M2

Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.

Applications & Processing

Applications: Lathe and planer tools, milling cutters, drills, woodworking cutters, form tools.

Processing: Very high hardening temperature demands good furnace control. Tougher than its reputation, but molybdenum grades have displaced it in most new tooling.

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Source: ASTM A600 / EN ISO 4957 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.