Fracture Micromechanism of Cryogenically Processed Vanadis 6 Tool Steel

Abstract:

The effect of cryogenic processing and tempering on selected mechanical properties and fracture micromechanism of Vanadis 6 high alloy cold work tool steel was analysed. The samples were processed in cold nitrogen gas at -140 °C for 48 h, and tempered at temperatures of 170 – 530 °C. It was found that the hardness of sub-zero treated Vanadis 6 steel decreases with increasing tempering temperature. The highest hardness of the specimen 960 HV10 was achieved by tempering at 170 °C and the lowest hardness 790 HV10 resulted from tempering at the highest tempering temperature, i.e. 530 °C. However, the hardness of conventional heat treated samples was less than 800 HV10 in full range of tempering temperatures. The fracture toughness of sub-zero treated samples does not differ from what was obtained by conventional heat treatment schedule except the case of the high tempering temperature of 530 °C where an increase in fracture toughness by approx.. 3 MPa.m^1/2 has been recorded. The carbides differ clearly in their role in the fracture propagation. While the secondary carbides undergo easily cleavage the eutectic carbides assist more probably decohesive fracture propagation.

• Periodical: Defect and Diffusion Forum (Volume 395)
• Pages: 45-54
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.395.45
• Online since: August 2019
• Authors: Juraj Ďurica*, Jana Ptačinová, Peter Jurči
• Keywords: Fracture Micromechanism, Fracture Toughness, Hardness, Subzero Treatment, Vanadis 6

References

[1] D. Das, A.K. Dutta, K.K. Ray, Influence of varied cryotreatment on the wear behaviour of AISI D2 steel, Wear 266 (2009) 297 – 309.

DOI: 10.1016/j.wear.2008.07.001

[2] P. Jurči, Cr-V Ledeburitic Cold-Work Tool Steels, Mater. Tehnol., 45 (2011) 383 - 394.

[3] D.N. Collins, Cryogenic treatment of tool steels, Adv. Mater. Process. 12 (1998) 24 – 29.

[4] D.N. Collins, J. Dormer, Deep Cryogenic Treatment of a D2 Cold-Work Tool Steel, Heat Treat. Met. 24 (1997) 71 - 74.

[5] J. Sobotová, P. Jurči, I. Dlouhý, The effect of sub-zero treatment on microstructure, fracture toughness, and wear resistance of Vanadis 6 tool steel. Mater. Sci. Eng. A652 (2016) 192 – 204.

DOI: 10.3390/met8121047

[6] K. Amini, A. Akhbarizadeh, S. Javadpour, Investigating the effect of holding duration on the microstructure of 1.2080 tool steel during the deep cryogenic treatment, Vacuum 86 (2012) 1534 – 1540.

DOI: 10.1016/j.vacuum.2012.02.013

[7] D. Das, A.K. Dutta, K.K. Ray, Sub-zero treatments of AISI D2 steel: Part I. Microstructure and hardness. Mater. Sci. Eng. A527 (2010) 2182 – 2193.

DOI: 10.1016/j.msea.2009.10.070

[8] P. Jurči, M. Dománková, L. Čaplovič, J. Ptačinová, J. Sobotová, P. Salabová, O. Prikner, B. Šuštaršič, D. Jenko, Microstructure and hardness of sub-zero treated and no tempered P/M Vanadis 6 ledeburitic tool steel. Vacuum 111 (2015) 92 – 101.

DOI: 10.1016/j.vacuum.2014.10.004

[9] ISO 12135:2016 Metallic materials — Unified method of test for the determination of quasistatic fracture toughness.

DOI: 10.3403/30394398u

[10] P. Jurči, M. Dománková, M. Hudáková, J. Ptačinová, M. Pašák, P. Palček, Characterization of microstructure and tempering response of conventionally quenched, short- and long-time sub-zero treated PM Vanadis 6 ledeburitic tool steel. Mater. Charact. 134 (2017) 398 – 415.

DOI: 10.1016/j.matchar.2017.10.029

[11] P. Jurči, I. Dlouhý, P. Priknerová, Z. Mrštný, Effect of Sub-Zero Treatment Temperatures on Hardness, Flexural Strength, and Fracture Toughness of Vanadis 6 Ledeburitic Die Steel, Metals, 8 (2018) Article Number 1047.

DOI: 10.3390/met8121047

[12] ASTM E975-13. Standard Practice for X-ray Determination of Retained Austenite in Steel with Near Random Crystallographic Orientation; ASTM Book of Standards: West Conshohocken, PA, USA, 2004; Volume 3.01.

DOI: 10.1520/e0975-03r08

[13] J. Ptačinová, P. Jurči, I. Dlouhý, Fracture toughness of ledeburitic Vanadis 6 steel after sub-zero treatment for 17 H and double tempering. Mater. Tehnol. 51 (2017) 729 – 733.

DOI: 10.17222/mit.2016.118

[14] J. Ďurica, P. Jurči, J. Ptačinová, Microstructural evaluation of tool steel Vanadis 6 after sub-zero treatment at -140 °C without tempering, Manufacturing Technology, 18 (2018) 222 – 226.

DOI: 10.21062/ujep/81.2018/a/1213-2489/mt/18/2/222

[15] S. Buytoz, Microstructural properties of M7C3 eutectic carbides in a Fe–Cr–C alloy, Mater. Lett., 60 (2006) 605 – 608.

DOI: 10.1016/j.matlet.2005.09.046