1.2550 AISI S1 is a high duty shock resisting alloy tool steel. In the hardened condition 1.2550 60WCrV7 is a heat resisting tool steel that combines great hardness with good toughness and shock resisting properties. 1.2550 tool steel is one of the shock resisting tool steel types with very good thoughness in combination with high hardenability. Impact-resistant, tungsten-alloyed cold-work tool.
General purpose, tungsten type of shock resisting tool steel. A versatile steel with excellent properties for cold battering tools and hot work shock applications. Low carbon content contributes to its toughness. Has sufficient carbide forming alloys to give ample abrasion resistance and depth of hardenability for the majority of shock tools. For additional wear resistance, carburize surface of tools during pack-hardening. Will still retain the shock resistance. Silicon content improves the hot work characteristics for shock tools at high temperatures.
Application include cutting tools (dies, punchers) for plate, woodworking tools, blanking dies for cutting sheet metals up to 12 mm thickness, trimming and spliting dies, cold piercing punches, performing punches, shear blades, chipping knives, pneumatic chisels, coining tools, cold shear blades, ejectors.
Forging: Heat the 1.2550 tool steel component slowly and uniformly to 1000°C. Forge within a range of 1000/800°C, reheating if necessary. Cool slowly (preferably in a furnace) to avoid setting up stresses. Annealing: Heat the 1.2550 tool uniformly to 770°C, equalise, then furnace cool.
Stress Relieving: If machining operations have been heavy or if the 1.2550 tool has an unbalanced section, remove stresses before hardening by heating up to 700°C, equalise, then cool slowly.
Hardening: Pre heat the 1.2550 tool steel to 650°C and thoroughly soak. Continue heating to the final hardening temperature of 900/950°C. Allow sufficient time for the component to be heated through. Quenching in oil.
Martempering: Martempering is an alternative hardening procedure for 1.2550 which may be used when suitable salt bath equipment is available.
Tempering: Heat uniformly and thoroughly at the selected tempering temperature and hold for at least one hour per inch of total thickness
Advantages
- Maximum shock resistance for cold or hot work applications
- Good wear resistance
- Good red-hardness value
Typical Analysis
CARBON ……………0.50 CHROMIUM ………..1.15
SILICON ……………0.75 TUNGSTEN ………..2.50
VANADIUM …………0.20
Heat Treatment
FORGING ………………………………..2000°F to 2100°F, stop at 1600°F
NORMALIZING ………………………...Do not normalize
ANNEALING ……………………………1475°F, cool slowly. Brinell 212 max
PREHEATING ……………………………1200°F – prior to hardening
HARDENING …………………………….1750 °F, oil quench to 150°F
TEMPERING ……………………………...300° to 500°F cold work, hardness Rockwell c-57-64, 1000° F, for hardness Rockwell C-47-42.
In the thoroughly annealed condition, has a machinability rating of 75, as compared with a rating of 100 for a one percent carbon tool steel.
Tempering Results
Specimens 1 in. diameter by 6 in. long were quenched in oil from 1750° F and tempered at 100°F intervals from 300°F, to 1200°F for one hour.
Tempering
Temperatures °F |
Hardness
Rockwell C |
| None |
57 |
| 300 |
55 |
| 400 |
54 |
| 500 |
53 |
| 600 |
51 |
| 700 |
51 |
| 800 |
50 |
| 900 |
49 |
| 1000 |
47 |
| 1100 |
45 |
| 1200 |
42 |
Results may be used as a guide in tempering tools to desired hardness. However, since 1 in. diameter specimens were used in this test, tools of heavy section or mass may be several points lower in Rockwell hardness for a given treatment.
| Tempering °C |
150 |
200 |
250 |
350 |
400 |
HRc |
62/61 |
61/60 |
60/59 |
58/57 |
55/54 |
