Shock Resistant Cold Work Die Steel Combines Toughness and Wear Resistance
Technical Guide
A shock-resistant cold work die steel with an excellent combination of toughness and wear resistance may be considered for tooling applications such as coining dies, blanking dies, slitter knives, chipper knives and rotary shears, among others.
Carpenter Micro-Melt® CD #1 alloy, developed by Carpenter Technology Corp., offers a combination of properties that have been found useful in coining applications as well as many types of cold work tooling applications.
The alloy is made by Carpenter's patented powder metallurgy process known as Micro-Melt Process. Steels made by this method have a refined microstructure with very fine grain size and smaller, more uniformly distributed carbide particles. Eliminated is the segregation found in conventional cast-wrought alloys.
Magnification at 1000 times has verified the fine microstructure of the new, highly alloyed material. The fine carbide distribution, combined with low sulfur content, make dies and tools of this alloy easy to polish. This characteristic makes the alloy an exceptional candidate for coining applications.
Consistent microstructure gives the alloy its good toughness and consistent, reproducible response to heat treatment. Fatigue resistance under repetitive compressive forces has been outstanding. The alloy balance, particularly nickel, contributes both to toughness and hardness.
Wear resistance comes from the grade's good hardness coupled with the formation of vanadium, chromium and molybdenum carbides. The steel can be heat treated in salt, vacuum or controlled atmosphere furnaces, and secondary hardened at 950°F (1066°C). Using this treatment, hardness levels up to 61/62 HRC can be achieved with low residual stress in the cold work tools or coining dies made from the material.
Like other Carpenter Micro-Melt alloys, the new CD#1 alloy is more forgiving during heat treatment than conventional tool steels. In addition to predictable response to heat treatment, the alloy remains more dimensionally stable when making a tool, and exhibits less out-of-round distortion after heat treatment. Machinability is also improved in the annealed condition.
The typical analysis of Micro-Melt CD#1 alloy is: carbon 0.70%, manganese 0.40%, silicon 1.00%, chromium 8.25%, molybdenum 1.40%, nickel 1.50%, vanadium 1.00%, nitrogen 0.09%, iron balance.
This material is available in round, square and flat bar; billet and powder.