Carbides Evolution and Tensile Property of 4Cr5MoSiV1 Die Steel with Rare Earth Addition

Hanghang Liu,Dianzhong Li,Hongwei Liu,Chen Sun,Paixian Fu,Jinzhu Gao

doi:10.3390/met7100436

Hanghang Liu, Dianzhong Li + Show 4 more

Open Access

https://doi.org/10.3390/met7100436

Copy DOI

Abstract

Studies of 4Cr5MoSiV1 die steel suggest that under appropriate conditions, additions of rare earth (RE) can enhance tensile property. This improvement is apparently due to the more uniform distribution of carbides and the enhancement of precipitation strengthening after RE additions. In this present work, the effect of the RE addition on the carbides evolution and tensile property of 4Cr5MoSiV1 steel with various RE contents (0, 0.018, 0.048 and 0.15 wt %) were systematically investigated. The two-dimensional detection techniques such as optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to investigate the carbides evolution of as-cast, annealed and tempered with RE addition. The results indicated that the carbides in 4Cr5MoSiV1 steels were modified by adding the suitable amount of RE. The eutectic structure and coarse eutectic carbides were all refining and the morphology of the annealed carbides initiated change from strip shape to ellipsoidal shape compared with the unmodified test steel (0RE). In addition, the amount of the tempered M8C7 carbides increased initially and then decreased with the alteration of RE addition from 0.018 to 0.15 wt %. Notably, the tensile test indicated that the average value of ultimate tensile strength (UTS) and elongation rate of 0.048RE steel increased slightly to 1474 MPa and 15%, higher than the 1452 MPa and 12% for the unmodified test steel (0RE), respectively. Such an addition of RE (0.048 wt %) would have a significant effect on the carbides evolution of as-cast, annealed and tempered and resulting in the tensile property of 4Cr5MoSiV1 die steel.

Highlights

Studies of 4Cr5MoSiV1 die steel suggest that under appropriate conditions, additions of rare earth (RE) can enhance tensile property
Researchers found that the uniform hardness, impact toughness, tensile strength and high temperature fatigue strength will be beneficial to prolong the service life when the die steel is subjected to intense friction and mechanical shock in service [3,4,5,6,7,8,9]
Fu [18] and Gao [19] reported that RE elements like Ce, La and Y can form highly stable oxides, oxy-sulphides and sulphides, which precipitate as solid particles in the melt due to their high melting temperatures

Summary

Introduction

Studies of 4Cr5MoSiV1 die steel suggest that under appropriate conditions, additions of rare earth (RE) can enhance tensile property This improvement is apparently due to the more uniform distribution of carbides and the enhancement of precipitation strengthening after RE additions. The tensile test indicated that the average value of ultimate tensile strength (UTS) and elongation rate of 0.048RE steel increased slightly to 1474 MPa and 15%, higher than the 1452 MPa and 12% for the unmodified test steel (0RE), respectively Such an addition of RE (0.048 wt %) would have a significant effect on the carbides evolution of as-cast, annealed and tempered and resulting in the tensile property of 4Cr5MoSiV1 die steel. The reason for the enhancement of the tensile property points to morphological changes of the phase constituents and phase fractions [15]

Results

Discussion

Conclusion