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

Abstract

Standard heat treatment of martensitic stainless steel consists of quenching and tempering. However, this results in high strength and hardness, while Charpy impact toughness shows lower values and a large deviation in its values. Therefore, a modified heat treatment of 0.1C-13Cr-3Ni martensitic stainless steel (PK993/1CH13N3) with intercritical annealing between Ac1 and Ac3 was introduced before tempering to study its effect on the microstructure and mechanical properties (yield strength, tensile strength, hardness and Charpy impact toughness). The temperatures of intercritical annealing were 740, 760, 780 and 800 °C. ThermoCalc was used for thermodynamic calculations. Microstructure characterization was performed on an optical and scanning electron microscope, while XRD was used for the determination of retained austenite. Results show that intercritical annealing improves impact toughness and lowers deviation of its values. This can be attributed to the dissolution of the thin carbide film along prior austenite grain boundaries and prevention of its re-occurrence during tempering. On the other hand, lower carbon concentration in martensite that was quenching from the intercritical region resulted in lower strength and hardness. Intercritical annealing refines the martensitic microstructure creating a lamellar morphology.

In Situ Observations of the Microstructural Evolution during Heat Treatment of a PH 13‐8 Mo Maraging Steel

“…However, a diffusion-controlled austenite formation accompanied with an inheritance of geometrically necessary dislocations was recently assessed to be the most probable variant for an alloy akin to PH 13-8 Mo maraging steels at a similar heating rate (3.3 K s À1 ). [43] Although effective refinement of the martensitic structure and an increase in toughness after intercritical annealing were reported for other martensitic steels, [19,49] it is proposed that a refinement of the PAG size and, subsequently, the martensitic structure through single intercritical annealing is impeded by the austenite memory effect in PH 13-8 Mo maraging steels. Insignificant change in the PAGs was also reported in the study by Guo et al [10] for the same steel after intercritical annealing at 760 °C for 2 h. On the contrary, effective grain refinement was observed by the same authors after a double sequence of solution and intercritical annealing.…”

Microstructure and Some Mechanical Properties of AISI 630 Stainless Steel Hardened by Precipitation Hardening

“…PH stainless steels belong to the Fe-Cr-Ni stainless steels family and contain alloying elements such as copper, molybdenum, niobium, titanium and aluminum [2]. These stainless steels are widely used in high-speed aircraft exteriors, missile hulls, watercraft, fuel tanks, aircraft landing gear, pumps, shafts, nuts, bolts, cutting tools, and couplings, because of their high strength, good ductility, nice fabrication characteristics and superior corrosion resistance [3].…”

A Novel Reticular Retained Austenite on the Weld Fusion Line of Low Carbon Martensitic Stainless Steel 06Cr13Ni4Mo and the Influence on the Mechanical Properties

“…Ni can enlarge the high-temperature austenite phase zone, increase the phase stability of austenite and the solubility of Cr, and improve the hardenability [8,9]. Normalizing and double-tempering treatment are usually applied with a normalizing temperature and tempering temperature of 950~1050 • C and ~600 • C, respectively [9][10][11][12]. After tempering, a mixed microstructure composed of lath martensite and trace reversed austenite dispersing between laths can be obtained [9,13,14].…”