Effects of alloying elements and cooling rates on the high-strength pearlite steels

Abstract

The effects of the alloying elements of Cr, Mn and the cooling rates after hot deformation on the microstructures and mechanical properties of pearlite steels were studied. Results show that increasing Cr and decreasing Mn significantly increase the eutectoid transformation temperature of steel. The grain sizes of prior austenite of the steels after hot deformation are ∼12 µm. However, the high-Cr–low-Mn steel exhibits a finer interlamellar spacing and some better mechanical properties than that of the high-Mn–low-Cr steel. A full pearlite microstructure with an interlamellar spacing of 97 nm was obtained on the former steel, which exhibits a hardness of HRC49, a tensile strength of 1700 MPa and an elongation of 19%.

Influence of Cooling Rate and Chemical Composition on Phase Transformation and Hardness of C70S6 Steel

“…Both the degree of super-cooling and the free enthalpy difference of ferrite transformation increase with the cooling rate increasing, while the critical nucleation free energies of grain boundaries and dislocations gradually decrease. Thus, the phase transformation temperature is decreased [12].Because the transformation of austenite to pearlite is a type of diffusion phase transformation and the degree of super-cooling increases with the cooling rate, the ferrite nucleation further is expedited but the grain growth process is suppressed, so that the microstructure is refined. Finally, the thin section sorbite is obtained.…”

Wear behaviour and microstructure evolution of pearlitic steels under block-on-ring wear process

“…In pearlitic steels with relatively large pearlite interlamellar spacing, the dislocations in wide ferrite were easy to multiply and slip, which resulted in the pile-ups of dislocations at the interfaces between ferrite and cementite. The increase in pile-ups resulted in the localised stress concentration which promoted the formation of large plastic deformation and micro cracks; thus, the steel with large pearlite interlamellar spacing possessed a low tensile strength [8,30,31]. Therefore, by comparing the properties of the three kinds of pearlitic steels treated by different heat treatments, the steel acquired from direct accelerated cooling after rolling obtained a thinner pearlite interlamellar spacing which possessed a relatively higher hardness and strength.…”

Effects of deformation and addition of aluminium on spheroidisation of high-carbon-bearing steel

“…The lamellar pearlite microstructures are obtained in all the steels, and the interlamellar spacings of the steels containing aluminium are thinner than that of 0Al steel. The interlamellar spacing values of the steels were calculated using Formulas (1) and (2) [22][23][24], and the results are listed in Table 2. It can be seen that adding aluminium can refine the interlamellar spacing of pearlite.…”