Numerical Simulation of Water Quenching of Large Size Steel Forgings: Effects of Macrosegregation and Grain Size on Phase Distribution

Abstract

In this paper, water quenching of large ingots was simulated using FORGE NxT 1.1 ® Finite Element code. Simulations were carried out for as-forged medium-carbon low-alloy steel. A novel method is proposed to simulate the different parts of a large size forged block with different chemical compositions and grain sizes using the multiple materials method. The effects of macrosegregation, grain size variation and cooling rate on phase distribution through the volume of the forged block were investigated. The delay in transformation kinetics, which is due to the effect of grain size variation and carbon content, was analyzed. Results show that macrosegregation and grain size variations significantly influence transformation start points and the volume fraction of phases that are present in each location of the forged ingot. The proposed prediction method was validated using high-resolution dilatometry experiments and X-ray diffraction measurements to evaluate accurately the volume fraction of martensite, bainite and the percentage of retained austenite for each condition.

Retained Austenite Decomposition and Carbide Precipitation during Isothermal Tempering of a Medium-Carbon Low-Alloy Bainitic Steel

“…The objective of the tempering process is to reduce or eliminate the undesirable retained austenite and improve the ductility of the material by decreasing the carbon supersaturation in the martensitic and bainitic constituents through carbide precipitation [ 6 , 7 ]. Carbon segregation, precipitation of transition carbides, retained austenite decomposition, carbide precipitation and carbide coarsening are the main microstructural changes that take place during the tempering process [ 8 , 9 , 10 , 11 ].…”

Real-time interface-tracking framework for the evolution of the phases during the quenching of the steel balls

“…Performing the simulation and assigning the constants given in the Table 3, the temperature T profile is illustrated in the Figure 7 and its respective transient development based on the couplings of the Equations 1, 2, 3 and 4 is shown in the Figure 8. Regarding the temperature dependence of the heat conductivity α for the microstructures (Austenite, Martensite, Bainite and Pearlite), we have used their average values in the range of the original temperature T 0 and the quench temperature T q from the respective temperature-dependent graphs [32].…”

Microstructure, Mechanical, and Corrosion Properties of Ni-Free Austenitic Stainless Steel Prepared by Mechanical Alloying and HIPping

“…It caused an increase of the interparticle (neck) contact area and a more intensive densification process [43]. The slightly lower density of the water cooled sample is difficult to explain, however, it may be related to the local martensitic transformation that may occur after fast cooling [44]. The heat treatment of the HIPped samples caused the grain growth (see Figure 8).…”