The influence of temper embrittlement on fracture toughness

Abstract

The susceptibility of an air-hardened martensitic stainless steel (En56C) to temper brittleness has been measured over a range of test temperatures from −150°C to room temperature, using the plane strain fracture toughness, K _lc, and the critical COD for rapid fracture. Valid K _lcvalues obtained at −150°C indicated a fall in toughness with increasing embrittlement time. The critical COD and the extent of slow crack growth preceding rapid fracture also decreased with embrittlement time, the effect becoming greater as the test temperature was increased.