Description
JIS G4404 SKS7 / DIN115W8 / Werkstoff Nr.1.2442 modified is a low alloy tool and die steel. 1.2442 is a relatively tough steel, with good wear resistance and hardenability used in custom kitchen knives, at max hardness.
JIS G4404 SKS7 / DIN115W8 / Werkstoff Nr.1.2442 modified is similar to Hitachi Aogami 1 steel with a bit less Carbon and Chromium, but a bit more Tungsten(W). Main drawback compared to Aogami and Shirogami series would be much higher allowed amount for contaminants like Sulfur (S) and Phosphorus (P). Still, very decent alloy with proper heat treatment and geometry for the right task.
Also known as Wolfram Special.
The Japanese standard SKS 7 also fits this chemistry.
JIS G4404 SKS7 tool steel chemical composition %
| Grade | C | Si | Mn | P | S | Ni | Cr | W | V | Cu | |
| SKS7 |
min max |
1.10 1.20 |
0.35 |
0.50 |
0.030 |
0.030 |
0.25 |
0.20
0.50 |
2.00
2.50 |
– |
0.25 |
| Cast
D3934M |
1.13 | 0.20 | 0.24 | 0.012 | 0.016 | 0.08 | 0.42 | 2.23 | 0.13 | ||
JIS G4404 SKS7 tool steel hardness in the hardened and tempered condition
| Grade | Annealed hardness | Quenched and tempered hardness | |||
| Temperature ℃ | HB max | Quenching temperature℃ | Tempering temperature℃ | Hardness HV min | |
| SKS7
|
750-800
slow cooling |
217 | 860
oil cooling |
180
air cooling |
746 (62HRC) |
