Shock-resistant cold work die steel

Citation

(2001), "Shock-resistant cold work die steel", Aircraft Engineering and Aerospace Technology, Vol. 73 No. 4. https://doi.org/10.1108/aeat.2001.12773dad.018

Shock-resistant cold work die steel

Shock-resistant cold work die steelKeywords: Carpenter Technology, Steel

A new shock-resistant cold work die steel claiming an excellent combination of toughness and wear resistance may be considered for tooling applications.

Carpenter Micro-Melt® CD #1 alloy, developed by Carpenter Technology Corp., is said to offer a combination of properties that have been found useful in many types of cold work tooling applications (Plate 8).

The new alloy is made by Carpenter's patented powder metallurgy process known as micro-melt process. Steels made by this method are described as having a refined microstructure with very fine grain size and smaller, more uniformily distributed carbide particles. The segregation found in conventional cast-wrought alloys are said to be eliminated.

Plate 8 Typical hardened and tempered microstructure of Carpenter Micro-Melt® CD #1 alloy at 1,000x

According to Carpenter magnification at 1,000 times has verified the fine microstructure of the new, highly alloyed material. The fine carbide distribution, combined with low sulfur content, makes dies and tools of this alloy easy to polish.

Consistent microstructure gives the alloy its good toughness and consistent, reproducible response to heat treatment. Carpenter also considers that 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 molybdemun carbides. The steel can reportedly be heat treated in salt, vacuum or controlled atmosphere furnaces, and secondary hardened at 950°F (1,066°C). Using this treatment, hardness levels up to 61/62 HRC are believed to be achievable with low residual stress in the cold work tools made from the material.

Like other Carpenter Micro-Melt alloys, the new CD# 1 alloy is claimed to be more forgiving during heat treatment than conventional tool steels. Carpenter informs us that 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 thought to be improved in the annealed condition.

The typical analysis of Micro-Melt CD#1 alloy is: carbon 0.70 per cent, manganese 0.40 per cent, silicon 1.00 per cent, chromium 8.25 per cent, molybdenum 1.40 per cent, nickel 1.50 per cent, vanadium 1.00 per cent, nitrogen 0.09 per cent, iron balance.

This new material is available in round, square and flat bar; billet and powder.

Further details are available from Carpenter Specialty Alloys. Tel: +2 610 208 2579; Fax: +1 610 736 8547; (Canada) Tel: +1 800 268 4740; Web site: www.cartech.com