The effect of the austenite grain refinement on the tensile and impact properties of cast Hadfield steel

Abstract

This paper studied the effect of the austenite grain refinement on the tensile and impact properties of a cast Hadfield steel (12 % Mn, 1.2 %C and 0.65 % Si). The austenite grain refinement was obtained by hafnium inoculation. Microstructural characterization showed that the Hf-refined cast Hadfield steel featured a grain size of 600 µm, while the non-refined condition presented a grain size of 3000 µm. Mechanical test results indicated that the austenite grain refinement promoted an increase in the values of the yield stress (6%), the ultimate tensile strength (37%), the toughness (88%), the work-hardening coefficient (50%) and the Charpy absorbed energy (15%). Microscopic characterization of the fractured test-pieces indicated that the grain refinement increased the proportion of plastic deformation by the twinning mechanism and furthermore improved the values of the mechanical properties of the cast Hadfield steel considerably.

Effect of titanium and nitrogen inoculation on the microstructure, mechanical properties and abrasive wear resistance of Hadfield Steels

“…The effect of grain size on yield strength is expected according to the Hall-Petch law. The strain hardening capacity was negatively affected by the increase in grain size, which is in agreement with the results observed by and Venturelli et al (2018). Nevertheless, these authors diverge on their conclusion about the mechanism that leads to this difference in strain hardening capacity.…”

“…The 12Mn sample depicted a small increase in im-pact resistance, whereas sample 12MnCr presented a slight decrease in the same property. Despite this decrease observed in the 12MnCrTi case, the obtained results are consistent with the expected values for Hadfield steels (Subramanyan et al, 1990;Kuyucak, 2004;Venturelli et al, 2018). Table 3 and Figure 6 show the results of dry sand rubber wheel abrasion tests.…”

“…Nevertheless, these authors diverge on their conclusion about the mechanism that leads to this difference in strain hardening capacity. Venturelli et al (2018) attributed the increase in the strain hardening coefficient in fine mi-crostructures to an increase in the twin density. On the other hand, suggested that the increase in the strain hardening coefficient in a fine grain microstructure is related to a stronger slip activity.…”

Cast Iron Cooling Rate Variation Using Cooling Channels: A Numerical Approach

“…Fast cooling results in grain refinement, while slow cooling produces coarse grain. The microstructural features of iron-based materials are refined with higher cooling rates [8] and this has an attendant positive impact on the mechanical properties [9][10][11]. It is, however, important to ensure even cooling as uneven cooling produces low-quality cast.…”

Investigation into Changes of Microstructure and Abrasive Wear Resistance Occurring in High Manganese Steel X120Mn12 during Isothermal Annealing and Re-Austenitisation Process

“…The heat treatment carried out and described in this article follows the trend of modifying high-manganese steel without the addition of carbide-forming elements. However, the selected heat treatment parameters and cooling conditions are designed to: (1) Avoid excessive austenite grain growth due to high temperature of solution heat treatment, which negatively affects mechanical properties [ 26 , 27 ]; (2) avoid the formation of micro-cracks [ 26 , 28 ] or the development of corrosion after the heat treatment [ 29 ] due to the use of salt solution in the cooling process; (3) maximise the proportion of pearlite colonies formation by long-term isothermal heating at relatively higher temperatures to sustain atomic diffusion.…”