Microstructure, Mechanical Properties, and Thermal Stability of Carbon-Free High Speed Tool Steel Strengthened by Intermetallics Compared to Vanadis 60 Steel Strengthened by Carbides

High speed tool steels are materials that exhibit superior mechanical properties (e.g., high hardness). They should also be resistant to thermal exposure to maintain high hardness during the machining process. In this paper, a C-free tool steel formed of Fe matrix and a Mo6Co7 intermetallic phase was studied. This steel was compared to the well-known Vanadis 60 steel containing Fe matrix and carbides. Microstructures were investigated by scanning (SEM) and transmission (TEM) electron microscopy, and the mechanical properties and thermal stability of both materials were compared. It was proven that the strengthening in the Vanadis 60 steel was mainly caused by the carbides, while the C-free steel was strengthened by the Mo6Co7 phase. The hardness values of both materials were comparable in the utilization state (approx. 950 HV). The hardness of Vanadis 60 steel decreased after several minutes of annealing at 650 °C under the value that enables material utilization. The hardness value of the steel strengthened by the intermetallics also decreased but significantly slower. Based on these results, the main finding of this study is that the C-free steel exhibited much better thermal stability and may be utilized at higher temperatures for longer periods of time than Vanadis 60.

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Enhanced High-Temperature Mechanical Properties of Al–Cu–Li Alloy through T1 Coarsening Inhibition and Ce-Containing Intermetallic Refinement

Materials ◽

10.3390/ma12091521 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1521 ◽

Cited By ~ 3

Author(s):

Xinxiang Yu ◽

Zhiguo Zhao ◽

Dandan Shi ◽

Han Dai ◽

Jie Sun ◽

...

Keyword(s):

Mechanical Properties ◽

Thermal Stability ◽

High Temperature ◽

Tensile Elongation ◽

Intermetallic Phase ◽

Phase Interface ◽

Thermal Exposure ◽

Main Element ◽

Temperature Deformation ◽

High Temperature Mechanical Properties

The effects of the addition of 0.29 wt% Ce on the high-temperature mechanical properties of an Al–Cu–Li alloy were investigated. Ce addition contributes to T1 (Al2CuLi) phase coarsening inhibition and Ce-containing intermetallic refinement which greatly improved the thermal stability and high-temperature deformation uniformity of this alloy. On the one hand, small Ce in solid solution and segregation at phase interface can effectively prevent the diffusion and convergence of the main element Cu on T1 phase during thermal exposure. Therefore, the thermal stability of Ce-containing alloy substantiality improves during thermal exposure at the medium-high-temperature stage (170 °C to 270 °C). On the other hand, the increment of the tensile elongation in Ce-containing alloy is much greater than that in Ce-free alloy at high temperatures tensile test, because the refined Al8Cu4Ce intermetallic phase with high-temperature stability are mainly located in the fracture area with plastic fracture characteristics. This work provides a new method for enhancing high-temperature mechanical properties of Al–Cu–Li alloy which could be used as a construction material for high-temperature structural components.

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Effects of Mg and Sc additions on the microstructure, mechanical properties, and thermal stability of a cast Al-2Li-2Cu-0.2Zr alloy after thermal exposure

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2019.02.062 ◽

2019 ◽

Vol 788 ◽

pp. 367-382 ◽

Cited By ~ 3

Author(s):

Xiaolong Zhang ◽

Guohua Wu ◽

Liang Zhang ◽

Chunchang Shi

Keyword(s):

Mechanical Properties ◽

Thermal Stability ◽

Thermal Exposure ◽

Thermal Stability Of

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Enhanced electrical conductivity and mechanical properties in thermally stable fine-grained copper wire

Communications Materials ◽

10.1038/s43246-021-00150-1 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Qingzhong Mao ◽

Yusheng Zhang ◽

Yazhou Guo ◽

Yonghao Zhao

Keyword(s):

Mechanical Properties ◽

Thermal Stability ◽

Electrical Conductivity ◽

Yield Strength ◽

High Speed ◽

Copper Wire ◽

Rapid Development ◽

Dislocation Slip ◽

Ultrafine Grains ◽

The Wire

AbstractThe rapid development of high-speed rail requires copper contact wire that simultaneously possesses excellent electrical conductivity, thermal stability and mechanical properties. Unfortunately, these are generally mutually exclusive properties. Here, we demonstrate directional optimization of microstructure and overcome the strength-conductivity tradeoff in copper wire. We use rotary swaging to prepare copper wire with a fiber texture and long ultrafine grains aligned along the wire axis. The wire exhibits a high electrical conductivity of 97% of the international annealed copper standard (IACS), a yield strength of over 450 MPa, high impact and wear resistances, and thermal stability of up to 573 K for 1 h. Subsequent annealing enhances the conductivity to 103 % of IACS while maintaining a yield strength above 380 MPa. The long grains provide a channel for free electrons, while the low-angle grain boundaries between ultrafine grains block dislocation slip and crack propagation, and lower the ability for boundary migration.

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Controlling the Thermal Stability of Kyanite-Based Refractory Geopolymers

Materials ◽

10.3390/ma14112903 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2903

Author(s):

Juvenal Giogetti Nemaleu Deutou ◽

Rodrigue Cyriaque Kaze ◽

Elie Kamseu ◽

Vincenzo M. Sglavo

Keyword(s):

Mechanical Properties ◽

Thermal Stability ◽

High Strength ◽

Treatment Temperature ◽

Strength Development ◽

Particle Sizes ◽

Cold Setting ◽

Thermal Stability Of ◽

Geopolymer Composites ◽

Refractory Composites

The present project investigated the thermal stability of cold-setting refractory composites under high-temperature cycles. The proposed route dealt with the feasibility of using fillers with different particle sizes and studying their influence on the thermo-mechanical properties of refractory geopolymer composites. The volumetric shrinkage was studied with respect to particle sizes of fillers (80, 200 and 500 µm), treatment temperature (1050–1250 °C) and amount of fillers (70–85 wt.%). The results, combined with thermal analysis, indicated the efficiency of refractory-based kyanite aggregates for enhancing thermo-mechanical properties. At low temperatures, larger amounts of kyanite aggregates promoted mechanical strength development. Flexural strengths of 45, 42 and 40 MPa were obtained for geopolymer samples, respectively, at 1200 °C, made with filler particles sieved at 80, 200 and 500 µm. In addition, a sintering temperature equal to 1200 °C appeared beneficial for the promotion of densification as well as bonding between kyanite aggregates and the matrix, contributing to the reinforcement of the refractory geopolymer composites without any sign of vitrification. From the obtained properties of thermal stability, good densification and high strength, kyanite aggregates are efficient and promising candidates for the production of environmentally friendly, castable refractory composites.

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