Effect of cobalt on the structure and properties of high-speed steels

Gulyaev, A. P.; Kupalova, I. K.

doi:10.1007/bf00654791

Cited by 18 publications

(9 citation statements)

References 3 publications

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“…Cobalt is not carbides former. It inhibits grain growth at elevated temperatures and improves substantially retention of hardness and high temperature strength [18]. The carbides are very hard and signi cantly contribute to wear resistance and hot hardness (hardness at high temperature) [19].…”

Section: Resultsmentioning

confidence: 99%

Failure Analysis of Super Hard End Mill HSS-Co

Tjahjana

Waloyo

Triyono³

2019

Open Engineering

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The failure of tools will make a large impact to the productivity, so it must be investigated to avoid the next failure. In this case, the super hard end mill HSS-Co list 4SE code 6210 was broken when it was used for side milling processing of mild steel AISI A36 with rotation speed, cutting speed and cutting depth of 540 rpm, 0.10 m/min (4 ipm) and 16 mm respectively. Standard procedure of failure analysis was performed including macro-micro investigation using Scanning Electron Microscopy (SEM) with energy-dispersive spectrometry (EDS) attachment, micro hardness test, and Finite Element Methods (FEM) simulation. The results of failure analysis showed that fracture occurred due to stress concentration and micro defects of the super hard end mill. Two parts of fracture surface, rough and fine surface were found. Based on SEM-EDS investigation, it was known that the content of tungsten (W) and cobalt (Co) elements on the rough and fine surface was inhomogeneous. Excessive Co and W elements appeared on the fine surface while they disappeared on the rough surface. Excessive Co will diffuse with tungsten and carbon and lead to the separation of tungsten and carbon elements, so it greatly destroyed the alloys and lead to form the non-stoichiometry carbide points. Hence, the defective manufacturing processes which made the elements distribute inhomogeneous is concluded as the reason of the super hard end mill failure.

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Section: Resultsmentioning

confidence: 99%

Failure Analysis of Super Hard End Mill HSS-Co

Tjahjana

Waloyo

Triyono³

2019

Open Engineering

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“…To overcome the tempering effects, a new alloy (LC2) has been developed through addition of Co, which was expected to stabilize the mobility of carbon in the solid solution. The Co addition changes the properties of the solid solution by increasing the binding strength and reduces the diffusion mobility of carbon [33,43], as a result of which martensitic softening was slowed down. Jakubéczyová et al [32] state that Co addition in HSS increases the secondary hardness by decreasing the solubility of W and Mo in the solid solution.…”

Section: Discussionmentioning

confidence: 99%

“…Jakubéczyová et al [32] state that Co addition in HSS increases the secondary hardness by decreasing the solubility of W and Mo in the solid solution. Addition of Co reduces the growth and coalescence of carbides and also raises the austenising and melting temperatures [33]. According to EBSD analysis, Co stays in the solid solution with Fe and is also adsorbed at the surface of carbides ( fig.8).…”

Section: Discussionmentioning

confidence: 99%

“…Similar to the LC1, the phase fraction of LC2 also consisted of VC, Mo 2 C and Cr 23 C 6 carbides. EBSD analysis revealed that Co stays in the solid solution with Fe and also adsorbed on the surfaces of carbides [32,33], while the rest is indexed as martensite. IPF mapping of LC2 also revealed a heterogeneous distribution of grain orientations, see fig.8b.…”

Section: Multilayer Depositionmentioning

confidence: 99%

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Development and characterization of multilayer laser cladded high speed steels

Rahman¹,

Capuano²,

Meer³

et al. 2018

Additive Manufacturing

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Two high speed steel (HSS) alloys were laser cladded on 42CrMo 4 steel cylindrical substrate by using a 4 kW Nd:YAG laser source. After optimization of the laser material processing parameters for single layers, multilayered clads were produced. Microstructural characterization of the laser deposits constitutes studies of the carbides and matrix, which was done by using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Electron Backscattered Diffraction (EBSD) and High Resolution Transmission Electron Microscopy (HRTEM). The strengthening mechanism of LC1 (Fe-Cr-MoW -V) was comprised of a martensitic matrix and retained austenite along with networks of VC and Mo 2 C eutectic carbides. Cr enriched fine carbides (Cr 7 C 3 and Cr 23 C 6) were embedded within the matrix. During laser cladding of the multilayer

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“…However better wetting properties and sintering performance are expected from M48 HSS due to the presence of Co as an alloying element and higher solubility of NbC in Co compared to Ni [6,11]. Moreover, Co improves the mechanical properties of the tool steel making it superior to 316 and 430 stainless steels [20]. The other benefit of using M48 as the binder is the presence of W, V, Mo in the form of cubic carbides in the structure.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Effect of sintering temperature on microstructural evolution of M48 high speed tool steel bonded NbC matrix cemented carbides sintered in inert atmosphere

Hadian

Zamani

Clemens

2018

International Journal of Refractory Metals and Hard Materials

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This work presents the results on microstructure and hardness evaluation of NbC-12wt% M48 high speed steel (HSS) cemented carbides, pressureless sintered at different temperatures in argon atmosphere. To evaluate the effect of sintering process on the microstructure, sintering was performed in the range of 1260 ˚C to 1420 ˚C according to dilatometer analysis. The sintered samples were characterized using several techniques, including determination of density by Archimedes, measurement of hardness and fracture resistance, microstructural analysis by scanning electron microscope (SEM), phase analysis using X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). As expected, microstructural results indicated higher NbC grain growth at elevated sintering temperatures. The high speed steel wetted the NbC particles at high temperature (> 1340 ˚C). As a result, the metallic binder spread and a homogenous distribution between the NbC grains could be achieved. Mechanical analysis showed a dependence of mechanical properties on NbC grain size and the state of the microstructure. A maximum hardness of 14.91 ± 0.14 GPa was measured for cemented carbide samples sintered at 1300 ˚C, while the highest fracture resistance (1.56 ± 0.3 MPa.m 1/2) was associated with the sample sintered at 1380 ˚C

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Effect of cobalt on the structure and properties of high-speed steels

Cited by 18 publications

References 3 publications

Failure Analysis of Super Hard End Mill HSS-Co

Failure Analysis of Super Hard End Mill HSS-Co

Development and characterization of multilayer laser cladded high speed steels

Effect of sintering temperature on microstructural evolution of M48 high speed tool steel bonded NbC matrix cemented carbides sintered in inert atmosphere

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