Optimising heat treatment requirements for improved toughness of V containing 3%NiCrMo steel

Abstract

AbstractOne major field of application of medium carbon low alloy steels is military hardware, especially the production of mortars. In manufacturing, it is usually necessary to adhere to specific standards; however, since economic and technological requirements depend on using scrap extensively, it can be difficult to keep minor additions within the specification. Heat treatment will therefore play an important role in obtaining the required mechanical properties. The combined effect of vanadium level and heat treatment cycles on strength and toughness of type 4337V (3%NiCrMo) 'gun steel' has been investigated. Vanadium is added mainly as a grain refiner, but it is also a strong carbide former, and therefore likely to reduce toughness. Conventional heat treatment (normalising at 900°C followed by quenching from 850°C), a modified heat treatment (double normalising at 900 and 800°C, successively, before the conventional treatment), and thermomechanical treatment (quenching in oil directly from the forging...