New Cobalt-Free Alloy Can Cut Weight of Key Components

I’ve written in recent years about how the American steel industry has moved to premium, higher-value products as a route to profitability and survival in the era of low-priced imports and huge buildups of basic steel capacity in China.

One of the companies that has made that transformation is Carpenter Technology. This month Carpenter announced commercialization of a high-strength, cobalt-free alloy called Premomet. The high toughness quenched and tempered alloy is produced in a recently built premium vacuum melt furnace in Reading, PA. It’s aimed at high-demand power train components in heavy-duty diesel engines and other commercial transportation and locomotive applications. It costs less than cobalt alloys. Cobalt prices soared from around $16 per pound in 2005 to more than $40 per pound in 2008, and have fallen considerably this year.

Due to its advanced strength and fracture toughness properties, design engineers can reduce the weight of parts for high-load applications by as much as 25 percent, according to Carpenter. The weight reduction estimates are based on the attainable ultimate tensile strength of 2,040 MPa (296 ksi) combined with the fracture toughness which is much higher than the lower-strength alternatives. Lighter-weight components could result in a reduction of stress on other parts, meaning lower energy consumption throughout a product’s lifecycle.

Carbon content is just 0.40 percent. Its chemistry includes molybdenum, vanadium and manganese. There is some chromium in the alloy, but it is not a stainless and may require plating or coating to resist corrosion. PremoMet is available in bar, hollow bar, wire, strip, plate and billet forms. Patents are pending.

Key property comparisons are indicated in the following table supplied by Carpenter Technology.