Evolution of microstructure and impact-strength energy in thermally and thermomechanically aged 15-5 PH

Abstract

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author -deposited version published in: http://oatao. • -400• C, the alloy embrittles through the decomposition of the martensite into iron-rich and chromium-rich domains. Depending on the ageing time, these domains are either interconnected or unconnected with each other. The embrittlement results in a drastic drop of the impact strength-energy and an increase of the ductile-to-brittle transition temperature. The initial microstructure and mechanical properties can be recovered through a re-homogenization of the distribution of chromium and iron atoms in the material in the case where the decomposition of the matrix is not too pronounced. The application of a stress higher than 60 per cent of the yield strength further enhances the ageing kinetics in the case where the combined effect of temperature and time results in the spinodal decomposition of the martensite.

Evolution of the microstructure of a 15-5PH martensitic stainless steel during precipitation hardening heat treatment

“…First, we compared the distribution of compositions M(C) measured by scanning a box of 100 atoms of base 1 × 1 nm 2 through the APT reconstructed volume, and compared it to the theoretical distribution R(C) for a random distribution of Cr atoms. The difference between the two distributions allows defining the degree of phase separation through the so-called V parameter [43][44][45][46]. Fig.…”

Microstructural evolution during long time aging of 15–5PH stainless steel

“…A possible application for this kind of stainless steel is as constitutive material of structural parts of airplane pylons. During use, due to the proximity of the pylon to the engine, the 15-5PH undergoes thermal aging at relatively low temperatures, around 300°C, leading to a significant change of the mechanical behavior of the alloy [1][2][3][4][5][6] that may lead to a decrease in toughness. This change in mechanical properties of the material is caused by evolutions of its complex initial microstructure, which we have presented in details in a former work [7].…”

The effect of heat treatment on the mechanical properties of a low carbon steel (0.1%) for offshore structural application

“…Subsequently, the samples were subjected to tempering heat treatment process to improve their toughness to fracture. 14,15 Tempering was carried out for 2 h and at the tempering temperatures of 450 °C, 550 °C, and 650 °C, which was followed by the various cooling methods from the temperature. The average cooling rates were 0.23, 36 and 50 °C/s for the air cooling, water cooling, and stirred water cooling methods, respectively.…”