Thermal aging of 16Cr – 5Ni – 1Mo stainless steel Part 2 – Mechanical property characterisation

Abstract

Mechanical property characterisation has been carried out on specimens of 16Cr -5Ni -1Mo stainless steel, subjected to various aging cycles. The heat treatment cycles involved solution treatment at 1050°C for 1 h followed by heating in the temperature range 400 -750°C for different holding times (1 -16 h). After heat treatment, tensile, hardness, impact, and creep tests were conducted. Specimens aged at 475°C exhibited maximum values of tensile strength and hardness with minimum values of ductility and impact toughness, while specimens aged at 625°C had maximum values of impact toughness and ductility. The results were correlated with the microstructural data presented in Part 1 of this study. Softening of the martensitic matrix at 625°C occurs as a result of the elimination of internal stresses, the decrease in the dislocation density, and the high volume fraction of austenite which lead to the drop in values of tensile strength and hardness. The results of the study reveal that aging at 550°C for 4 h gives the optimum combination of strength, hardness, ductility and toughness for this steel.MST/5715

Austenite reversion in low-carbon martensitic stainless steels – a CALPHAD-assisted review

“…1Mo (wt.%) soft martensitic stainless steel (EN 1.4418) at room temperature after 4 h soaking at various temperatures, adapted from Refs [13,14]…”

“…Fraction austenite and mechanical properties of a 16Cr-5Ni-1Mo stainless steel at room temperature in the hardened condition (HC) and after 4 h soaking at various temperatures: (a) Ultimate tensile strength (UTS), 0.2% yield strength (YS), elongation and fraction austenite ( ); (b) Hardness and Charpy V impact toughness; The lines are spline functions of measured data (symbols) and do not represent physical values (adapted from Dawood et al[13,14]) Cr and Ni in austenite and ferrite by computing phase equilibria (Thermo-Calc 2017a[92] with TCFE6 database[69]). For this purpose, the alloying elements Cr, Ni, Mo, Mn, Si, Cu, C and N and the phases fcc, bcc, cementite, M 6 C, M 7 C 3 and M 23 C 6 were taken into account, representing the most common elements and phases reported in literature[93].…”

In-situ analysis of redistribution of carbon and nitrogen during tempering of low interstitial martensitic stainless steel

“…In martensitic stainless steels, annealing in the inter-critical region between A 1 and A 3 leads to formation and stabilization of reversed austenite at lath boundaries [3][4][5]. Such dual phase microstructure significantly enhances toughness and ductility, and reduces yield strength, hardness and ultimate tensile strength [6][7][8].…”

Effect of Intercritical Annealing on the Microstructure and Mechanical Properties of 0.1C-13Cr-3Ni Martensitic Stainless Steel

“…MSS combine good corrosion resistance of the high chromium content and high hardness of martensite, which is mainly determined by the carbon content. They exhibit good ductility, even at high strengths, excellent impact toughness, and resistance to wet abrasion and cavitation [1,7,9,10]. However, MSS have the lowest corrosion resistance among stainless steels, due to chromium and molybdenum restrictions, which are needed for full austenitisation during the heat treatment process.…”