SBIR-STTR Award

The proposal submitted herein is based on prior research into effects of various groups of alloying elements on structure and properties of alpha- and gamma-iron based steels. Developed theory and previously obtained test results indicate that a complex of excellent mechanical characteristics (strength, ductility and fracture toughness) can be achieved in low alloy steels without the need for expensive purification processes (reduction in the level of S, P and other undesirable elements) and / or high levels of Co, Ni, Mo. These properties can be obtained through proper selection of relatively inexpensive alloying elements based, among other factors, on the element's atomic structure, their solubility in iron and their inter-crystalline and inter-phase adsorption activity. The objective of this proposal is to demonstrate that our alloying methodology allows production of relatively inexpensive steel alloys with excellent combination of mechanical properties - tensile strength, ductility, impact strength and fracture toughness, with yield strength and impact strength values within the target ranges of 235-325 ksi and 30-34 Ft-lbs respectively. It is expected that processing characteristics of these alloys will be comparable to common medium-carbon steel grades. Having also low cost, proposed alloys could potentially find wide military and commercial applications. Having low cost and excellent combination of mechanical and processing characteristics, proposed steel alloys could find use in various industries, potentially replacing some of the more expensive grades currently on the market.

Achieving a combination of high level of strength and toughness in metal alloys has always been the goal of metallurgical research, particularly true in development of construction steel alloys. Significant advances have been made in this area in the past twenty years, culminating with introduction of alloys AF1410 and AerMet100. Unfortunately the enhancement of properties was typically obtained through expensive processing and through use of substantial concentrations of cobalt and nickel. This drove the price of such alloys 6-10 times that of ordinary steel. At such price levels these grades are only suitable for the most exclusive and critical applications. Phase I research demonstrates feasibility of producing steel alloys with similar level of strength and toughness as that of HP9-4-20 and AerMet100, but at substantially reduced cost. This is accomplished through utilization of conventional production / processing methods and elimination from the composition of very expensive cobalt. These researchers believe that continued development will lead to production of an alloy with yield strength of 235-250 ksi and impact strength of 30-32 ft-lb but at production cost of under $1 per pound. This would represent a significant improvement over alloys currently utilized in the area of air delivered munitions.

Keywords:
high strength, yield strength, toughness, impact strength, steel alloy, nickel, quenching and tempering, hardness