The Effect of Heat Treatment Process Parameters on Mechanical Properties, Precipitation, Fatigue Life, and Fracture Mode
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JMEPEG (2018) 27:5246–5253 https://doi.org/10.1007/s11665-018-3625-y
The Effect of Heat Treatment Process Parameters on Mechanical Properties, Precipitation, Fatigue Life, and Fracture Mode of an Austenitic Mn Hadfield Steel S.H. Mousavi Anijdan
and M. Sabzi
(Submitted January 10, 2018; in revised form July 4, 2018; published online September 6, 2018) In this study, the effect of cooling rate after heat treatment on mechanical properties, fatigue life, precipitation and fracture mode of an austenitic Mn Hadfield steel was investigated. Cast samples of the Hadfield steel were heat treated at 1100 C for 2 h. The samples were subsequently quenched in pure water and also in 3 wt.% NaCl salt bath. Optical microscope (OM) and scanning electron microscope (SEM) were used to analyze microstructure and fracture surfaces. Transmission electron microscope (TEM) was used to assess the precipitates. X-ray diffraction (XRD) was used to determine the phases formed. Mechanical properties and fatigue life were determined by uniaxial tensile test, bending fatigue and hardness measurements. Results showed that the sample quenched in salt bath had lower Mn3C precipitates, hardness, yield and tensile strengths. Instead, this situation resulted in a more ductile fracture mode and higher formability. Finally, the fatigue life of the sample quenched in salt bath was longer than the one quenched in pure water. Keywords
austenitic Mn Hadfield steel, fatigue life, fracture mode, mechanical properties, cooling rate
1. Introduction An austenitic Mn steel that contained about 1.2 wt.%C and 12%Mn was first produced by Robert Hadfield in 1882. Since then, a significant deal of improvement was achieved in the Hadfield steels. Hadfield steel is a non-magnetic steel containing 1-1.4%C and 10-14%Mn which has very good work hardening capability together with high wear resistance. This steel, with its high strength, good formability and wear resistivity, is widely used in different industries such as cement, mining, construction, and railway, etc (Ref 1-3). Alloying elements are often added to the compositions of Hadfield steels depending on the application. Of the most important alloying elements added is Ti which reduces the grain size of the steel and increases its hardness (Ref 4, 5). Although Ti(N,C) increases the hardness and wear resistance of the Hadfield steels, the formation of TiC comes at the expense of lower formability (Ref 6). Srivastava and Das reported that the wear resistance of the steel can be substantially improved by producing a composite containing Hadfield steel matrix and TiC particle reinforcement (Ref 7). Srivastava et al. also assessed corrosion behavior of composites with Hadfield steel as the matrix and found that TiC particles would reduce corrosion resistance (Ref 8). Al is another important element that was paid attention to in the Hadfield steels for grain refinement purposes. It was found that increasing the amount of Al in Mn steels, increases the driving force for the transformation of austenite to martensite and
S.H. Mousa
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