Investigation of Size Effects Due to Different Cooling Rates of As-Quenched Martensite Microstructures in a Low-Alloy Steel

Abstract

Martensite transformation is a complex mechanism in materials that is classically initiated by a suitable heat treatment. This heat treatment process can be optimized based on a better understanding of the physical mechanisms on the length scale of several prior austenite grains. It is therefore appropriate to consider individual process steps of heat treatment in isolation. The aim of this study is to characterize the microstructural size changes caused by a variation of the cooling rate applied during the quenching process. For this purpose, individual martensitic microstructures from different heat treatments are analyzed using the electron backscatter diffraction (EBSD) method. With special orientation relationships between the parent austenite and martensite, the structure of the prior austenite grains and the close packet plane packets can then be reconstructed. The influence of the heat treatments on these characteristics as well as on the martensite blocks is thus quantified. No significant influence of the quenching rate on the sizes of martensite blocks and packets could be found.

Effect of Different Quenching Methods on the Microstructure and Mechanical Properties of 30MnB5NbTi

“…However, Villa [19] studied the effect of cooling rate on microstructure in the range of 1.5-50 k min À1 , and observed no effect of cooling rate on microstructure scale was observed. Marius [20] also did not find that the quenching rate has a significant effect on the size of martensite block and packet. Some discussions on the influence of the quenching method on the microstructure and mechanical properties can be found in the relevant researches.…”

“…[45] In this study, the size of martensite decreases with the increase of cooling rate, which is in contrast to the study of Marius. [20] Marius proposed that the quenching rate has no significant effect on the size of martensite block and packet. This motivates a detailed discussion of the differences.…”

“…However, Villa [ 19 ] studied the effect of cooling rate on microstructure in the range of 1.5–50 k min −1 , and observed no effect of cooling rate on microstructure scale was observed. Marius [ 20 ] also did not find that the quenching rate has a significant effect on the size of martensite block and packet.…”

Effect of Microstructural Evolution on the Mechanical Properties of Ni-Cr-Mo Ultra-Heavy Steel Plate

“…The different cooling rates across the thickness under the quenching process is the main factor that affects the microstructural homogeneity [ 5 , 6 , 7 ]. In general, a heavy plate under the roller quenching process mainly consisted of three types of microstructure: martensite (M), martensite/lath bainite (M/LB) and lath bainite/granular bainite (LB/GB) [ 8 , 9 , 10 ].…”

Effect of cooling rate on the microstructures of three low carbon alloys with different manganese and molybdenum contents

“…Su et al [23] combined dilatometric and electron backscattered diffraction (EBSD) measurements, but only for constituent identification. Graf et al [24] used EBSD to investigate the influence of the cooling rate on martensite on a low-alloy steel. They found no significant dependence of the cooling rate on the block and packet.…”