The Influence of Austenitization Temperature on the Mechanical Properties of a Prehardened Mould Steel

Hoseiny, Hamed; Caballero, Francisca G.; Martín, David San; Capdevila, Carlos

doi:10.4028/www.scientific.net/msf.706-709.2140

Cited by 15 publications

(11 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They have concluded that the hierarchical arrangement of packets/blocks and lath boundaries allows to accommodate the crystallographic shears of the transformation; this ensures that the net strain in the prior austenite grain is pure dilatation. Additionally, experimental evidence has shown that the prior-austenite grain size has a strong effect on the scale of packets and blocks and almost negligible effects on the lath substructure development [9][10][11][12]. This implies that the microstructure in the lath boundaries is practically independent of the prior-austenite grain size.…”

Section: Introductionmentioning

confidence: 92%

A model for the microstructure behaviour and strength evolution in lath martensite

Galindo-Nava

Rivera-Dı́az-del-Castillo

2015

Acta Materialia

292

View full text Add to dashboard Cite

a b s t r a c tA new model describing the microstructure and strength of lath martensite is introduced. The packet and block size were found to linearly depend on the prior-austenite grain size when introducing relevant crystallographic and geometric relationships of their hierarchical arrangements. A mechanism for the lath boundary arrangement within a block is postulated to ensure complete carbon redistribution to the lath boundaries. Accordingly, the dislocation density is obtained by considering the lattice distortion energy within a lath being equal to the strain energy of the dislocation density at the lath boundaries. Tempering effects are introduced by estimating the extent of carbon diffusing away from the lath boundaries; this mechanism relaxes the Cottrell atmospheres of lath dislocations and coarsens the boundaries. The yield stress as well as the microstructure evolution during tempering are successfully predicted by combining these results. The model is further extended to describe the yield stress in dual-phase steel microstructures by employing the iso-work principle. The model predictions are validated against experimental data in seven martensitic and five dual-phase steels, where the prior-austenite grain size, carbon content, tempering conditions and martensite volume fraction are employed as input. These results cover wide composition, initial microstructure and tempering conditions.

show abstract

Section: Introductionmentioning

confidence: 92%

A model for the microstructure behaviour and strength evolution in lath martensite

Galindo-Nava

Rivera-Dı́az-del-Castillo

2015

Acta Materialia

292

View full text Add to dashboard Cite

show abstract

“…often noticed that a steel containing large austenite grains forms coarse martensite. For example, a tool steel with 0.39-C, 1.95-Cr, 0.27-Mo, 1.0-Ni (wt.%) was investigated after austenitisation at several temperatures from 900 °C to 1050 °C [49]. It was reported that the prior austenite grain size increased from 23.5 µm to 80 µm, which caused an increase in martensite packet size from 9.7 to 28.5 µm while the martensite lath width also increased from 0.60 to 0.69 µm.…”

Section: The Effect Of Austenitisation Temperaturementioning

confidence: 99%

EBSD Analysis of Blocky Structures in Hardened and Tempered Microstructures of a 5 wt.% Cr Cold Work Tool Steel

Rehan¹,

Thuvander

Högman³

et al. 2021

Metallogr. Microstruct. Anal.

View full text Add to dashboard Cite

The hardened microstructure of 5 wt.% Cr cold work tool steels is mainly martensitic with significant amount of retained austenite and some undissolved carbides. Whereas the microstructure after tempering shows significant amounts of angular shaped blocky regions, which are interpretated as retained austenite or fresh martensite. The distinction between the phases is difficult due to the morphological similarities. Therefore, the blocky regions are characterized by electron backscatter diffraction to better understand the microstructures. The results showed that the characterisation of blocky structures in the microstructure of a 5 wt.% Cr cold work tool steels varied according to the austenitisation and tempering temperatures as well as the holding time at the tempering temperature. Electron backscatter diffraction of as-quenched microstructures revealed that the blocky structures were either retained austenite, fresh martensite or a combination of large part of fresh martensite with minute amounts of retained austenite. The blocky structures were entirely retained austenite after tempering at 200 °C. Tempering at 525 °C, for holding times of 0.1 or 0.5 h, more blocky regions were retained austenite contrasting to the blocky regions for holding times of 1 or 2 h, which were largely fresh martensite. It was further concluded that electron backscatter diffraction is a suitable technique for characterisation of blocky structures provided that the specimens are prepared by electro-polishing while X-ray diffraction is best suited for a bulk measurement of retained austenite.

show abstract

“…However, in some studies, transgranular crack initiation and early short crack propagation along martensitic laths were also observed [15,19]. A frequently used explanation for intergranular crack initiation and early short crack propagation at PAGBs is the preferential formation of carbides [25][26][27][28][29][30][31][32] or segregations [25,26,[28][29][30][31] along microstructural interfaces. Further reasons are the impingement of slip bands at PAGBs [20,33,34] or the anisotropic elastic and plastic properties of the grains [17,18,21,[35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Influence of Residual Stresses on the Crack Initiation and Short Crack Propagation in a Martensitic Spring Steel

Wildeis

Christ

Brandt

2022

Metals

View full text Add to dashboard Cite

The crack initiation and short crack propagation in a martensitic spring steel were investigated by means of in-situ fatigue testing. Shot peened samples as well as untreated samples were exposed to uniaxial alternating stress to analyze the impact of compressive residual stresses. The early fatigue damage started in both sample conditions with the formation of slip bands, which subsequently served as crack initiation sites. Most of the slip bands and, correspondingly, most of the short fatigue cracks initiated at or close to prior austenite grain boundaries. The observed crack density of the emerging network of short cracks increased with the number of cycles and with increasing applied stress amplitudes. Furthermore, the prior austenite grain boundaries acted as obstacles to short crack propagation in both sample conditions. Compressive residual stresses enhanced the fatigue strength, and it is assumed that this beneficial effect was due to a delayed transition from short crack propagation to long crack propagation and a shift of the crack initiation site from the sample surface to the sample interior.

show abstract

The Influence of Austenitization Temperature on the Mechanical Properties of a Prehardened Mould Steel

Cited by 15 publications

References 16 publications

A model for the microstructure behaviour and strength evolution in lath martensite

A model for the microstructure behaviour and strength evolution in lath martensite

EBSD Analysis of Blocky Structures in Hardened and Tempered Microstructures of a 5 wt.% Cr Cold Work Tool Steel

Influence of Residual Stresses on the Crack Initiation and Short Crack Propagation in a Martensitic Spring Steel

Contact Info

Product

Resources

About