Effect of Heat Treatment on Microstructure and Mechanical Properties of 12Cr–10Ni–0.25Ti–0.7Mo Stainless Steel

Abstract

In this investigation, a precipitation hardenable martensitic stainless steel (12Cr-10Ni-0.25Ti-0.7Mo) was subjected to different heat treatment cycles to study their influence on the microstructure and mechanical properties. The heat treatment cycles include solution treatment (S), cryogenic treatment (C), and aging (A). Two solution treatment temperatures, 750 and 1000°C, and two aging temperatures, 250 and 500°C, were selected. Solution treatment was followed by a cryogenic treatment at-70°C for 2 h and an aging treatment at the aforementioned temperatures. Transmission electron microscopy of the solution-treated samples showed four phases: martensite matrix, M 23 C 6 carbide, Ti(C, N), and retained austenite. On aging at 500°C, an additional phase (Ni 3 Ti precipitates) was observed in the martensite matrix. Mechanical properties were evaluated at room temperature for all the heat-treated samples. A reasonable increase in yield strength (YS) was observed after cryogenic treatment possibly due to transformation of retained austenite to martensite. After aging at 500°C, a significant increase in the YS was observed over solution-treated condition. This increase in YS after aging is attributed to precipitation of fine Ni 3 Ti precipitates. Solution treatment temperature had an insignificant effect on the mechanical properties of the stainless steel.

Microstructure and Properties of 15Cr‐5Ni‐1Mo‐1W Martensitic Stainless Steel

“…Use of cryo treatment is well known for high carbon MSS used in wear applications . These heat treatments are used for accomplishing specific functions (i) ST (950–1050°C) to achieve supersaturated solid solution which facilitates proper precipitation; (ii) CT (−70 to −196°C) to achieve fully martensite structure which ensures dimensional stability and imparts strength; (iii) Aging (400–500°C) to improve the strength by formation of precipitates of Cu, Ni 3 Ti, Ni 3 Mo, Mo 2 C, NiAl . Few martensitic stainless steels based on Fe‐15Cr‐(X)Ni with the addition of Mo, Cu, and Al were extensively studied for microstructure and properties after different heat treatment .…”

Effect of Cold Work, Ageing on Hardness and Ultimate Tensile Strength of Microalloyed Steel

“…The strong interaction of dislocation and precipitates restricts the recrystallisation and retain the higher hardness values even after prolonged ageing [32 & 33]. Many renowned researchers [32][33][34][35][36][37][38] have applied many techniques, e.g., heat treatment, aging, adding the alloying elements and different Thermomechanical Treatments (TMT) for improving the mechanical properties of steels. Many different production methods have also been modified.…”

“…Many different production methods have also been modified. Moreover, to improve the resistance of metals, following methods, viz, cold working (CW), Solid Solution Hardening (SSH) and precipitation hardening have been applied in the literature [33][34][35][36][37][38][39][40][41][42][43][44].…”