Microstructural evolution and mechanical behaviour of boronized martensitic stainless steels

Abstract

13Cr-4Ni and 16Cr-5Ni martensitic stainless steels are boronized at 900°C, 950°C and 1000°C for 2, 4, 6, 8 h using powder pack boronizing followed by tempering at 600°C for 2 h. Boronized layer morphology, composition and case depth are studied using optical microscopy, XRD, XPS and SEM. The influence of temperature and duration of boronizing on the growth kinetics of boronized layer is studied. Higher alloy content of 16Cr-5Ni MSS resulted in higher activation energy of boronizing, limiting the attainable case depth. Higher boronizing temperatures produced additional borides besides iron borides that increased hardness and decreased ductility, strain energy density and fracture toughness. Identified boronizing parameters could be useful in enhancing the performance of these grades in hydraulic machinery.

Numerical Simulation of Reversed Austenite Evolution during Intercritical Tempering of Low-Carbon Martensitic Stainless Steel

“…Low-carbon martensitic stainless steels with excellent comprehensive mechanical properties and an adjustable structure are widely used in many fields such as petroleum pipelines and hydraulic turbines [1][2][3][4][5]. With the further development of energy resources in extreme environments such as the seabed and the Arctic, higher requirements are put forward for the performance of low-carbon martensitic stainless steels [6,7]. Lowcarbon martensitic stainless steels with a microstructure consisting of hard martensite lath embedded in soft and ductile reversed austenite possess an outstanding combination of strength and formability.…”