Quantitative high temperature calorimetry on precipitation in steel and nickel alloys

Rowolt, Christian; Andreazza, Philipp; Keßler, Olaf

doi:10.1016/j.tca.2019.01.026

Cited by 12 publications

(12 citation statements)

References 16 publications

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“…For instance, quench-induced precipitation in magnesium alloys [123] and the tempering of steels have been analysed [221,222]. Recently, the DSC method for the analysis of solid-solid phase transformation kinetics was successfully adapted for use with high-temperature alloys up to 1100 • C [122]. The in situ analysis of quench-induced precipitation in precipitation hardening martensitic steels [122,131,215], and Ni-based alloys [122] has successfully been demonstrated.…”

Section: Application Of the Derived Dsc Methods To Other Alloy Systemsmentioning

confidence: 99%

“…Ni-based alloys can also benefit from precipitation strengthening. Recently the precipitation behaviour of Inconel 718 (a Ni-17Cr-17Fe-5Nb-3Mo alloy, mass fraction in % ) during cooling from solution treatment was investigated [122]. Figure 84a shows continuous DSC cooling curves for this alloy after solution annealing at 980 °C for 60 min, and Figure 84b illustrates the hardness and the specific precipitation heat, which depend upon the cooling rate.…”

Section: Application Of the Derived Dsc Methods To Other Alloy Systemsmentioning

confidence: 99%

“…It may be difficult to find appropriate reference material, but in the case of Al alloys, pure Al has proven to be very well suited [120,121]. Pure Al reference samples are preferably used in a pre-oxidised condition, i.e., heated once before the actual measurement; however, there are various strategies for obtaining a suitable reference sample [122], and changes in the sample mass to adjust the total heat capacities of the sample and reference sample may further improve the signal quality [122,123]. Figure 6.…”

Section: Basic Concepts Of Dsc Measurementsmentioning

confidence: 99%

“…To obtain good zero-level accuracy, it is important to ensure that symmetry is maintained within the experimental setup. This includes sample and reference heat capacities [122,123], crucible or pan masses/heat capacities, and of course sample positioning and potentially sensor cover placement [125].…”

Section: Zero-level Accuracymentioning

confidence: 99%

“…This may be caused by slight differences in the sample position for each individual measurement, for instance [125]. Thus, the raw DSC data must undergo a sophisticated data treatment prior to evaluation, including baseline subtraction in each case, and possibly also the elimination of the remaining zero-level curvature [120] or a mean value curve calculation [122,123,127]. If efforts are made to ensure the best zero level quality, a result that is straight and close to zero can be achieved.…”

Section: Zero-level Accuracymentioning

confidence: 99%

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Review of the Quench Sensitivity of Aluminium Alloys: Analysis of the Kinetics and Nature of Quench-Induced Precipitation

et al. 2019

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For aluminium alloys, precipitation strengthening is controlled by age-hardening heat treatments, including solution treatment, quenching, and ageing. In terms of technological applications, quenching is considered a critical step, because detrimental quench-induced precipitation must be avoided to exploit the full age-hardening potential of the alloy. The alloy therefore needs to be quenched faster than a critical cooling rate, but slow enough to avoid undesired distortion and residual stresses. These contrary requirements for quenching can only be aligned based on detailed knowledge of the kinetics of quench-induced precipitation. Until the beginning of the 21st century, the kinetics of relevant solid-solid phase transformations in aluminium alloys could only be estimated by ex-situ testing of different properties. Over the past ten years, significant progress has been achieved in this field of materials science, enabled by the development of highly sensitive differential scanning calorimetry (DSC) techniques. This review presents a comprehensive report on the solid-solid phase transformation kinetics in Al alloys covering precipitation and dissolution reactions during heating from different initial states, dissolution during solution annealing and to a vast extent quench-induced precipitation during continuous cooling over a dynamic cooling rate range of ten orders of magnitude. The kinetic analyses are complemented by sophisticated micro- and nano-structural analyses and continuous cooling precipitation (CCP) diagrams are derived. The measurement of enthalpies released by quench-induced precipitation as a function of the cooling rate also enables predictions of the quench sensitivities of Al alloys using physically-based models. Various alloys are compared, and general aspects of quench-induced precipitation in Al alloys are derived.

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Section: Application Of the Derived Dsc Methods To Other Alloy Systemsmentioning

confidence: 99%

Section: Application Of the Derived Dsc Methods To Other Alloy Systemsmentioning

confidence: 99%

Section: Basic Concepts Of Dsc Measurementsmentioning

confidence: 99%

Section: Zero-level Accuracymentioning

confidence: 99%

Section: Zero-level Accuracymentioning

confidence: 99%

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Review of the Quench Sensitivity of Aluminium Alloys: Analysis of the Kinetics and Nature of Quench-Induced Precipitation

et al. 2019

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Dissolution and precipitation of copper-rich phases during heating and cooling of precipitation-hardening steel X5CrNiCuNb16-4 (17-4 PH)

et al. 2020

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Continuous heating transformation (CHT) diagrams and continuous cooling transformation (CCT) diagrams of precipitation-hardening steels have the drawback that important information on the dissolution and precipitation of Cu-rich phases during continuous heating and cooling are missing. This work uses a comparison of different techniques, namely dilatometry and differential scanning calorimetry for the in situ analysis of the so far neglected dissolution and precipitation of Cu-rich phases during continuous heating and cooling to overcome these drawbacks. Compared to dilatometry, DSC is much more sensitive to phase transformation affecting small volume fractions, like precipitation. Thus, the important solvus temperature for the dissolution of Cu-rich phases was revealed from DSC and integrated into the CHT diagram. Moreover, DSC reveals that during continuous cooling from solution treatment, premature Cu-rich phases may form depending on cooling rate. Those quench-induced precipitates were analysed for a broad range of cooling rates and imaged for microstructural analysis using optical microscopy, scanning electron microscopy and transmission electron microscopy. This information substantially improves the CCT diagram.

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Continuous Heating Dissolution and Continuous Cooling Precipitation Diagrams of a Nickel-Titanium Shape Memory Alloy

Rowolt

Milkereit

Broer

et al. 2021

Shap. Mem. Superelasticity

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Binary NiTi alloys are the most common shape memory alloys in medical applications, combining good mechanical properties and high biocompatibility. In NiTi alloys, the shape memory effect is caused by the transformation of an austenite phase to a martensite phase and the reverse process. Transformation temperatures are strongly influenced by the exact chemical composition of the NiTi phase and the presence of precipitates in the microstructure induced by thermo-mechanical treatment, especially solution annealing and ageing. Isothermal time–temperature precipitation diagrams can be found in the literature. Cooling is frequently not considered, as water quenching is typically assumed to be sufficient. To the best of our knowledge, continuous heating dissolution (CHD) and continuous cooling precipitation (CCP) diagrams do not exist. Differential scanning calorimetry (DSC) is a common method to analyse the austenite/martensite transformation in shape memory alloys, but it has not yet been used to analyse precipitation processes during continuous temperature changes. We have enabled DSC to analyse dissolution and precipitation processes in situ during heating as well as during cooling from the solution annealing temperature. Results are presented as CHD and CCP diagrams, including information from microstructure analysis and the associated changes in the austenite/martensite transformation temperatures.

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Quantitative high temperature calorimetry on precipitation in steel and nickel alloys

Cited by 12 publications

References 16 publications

Review of the Quench Sensitivity of Aluminium Alloys: Analysis of the Kinetics and Nature of Quench-Induced Precipitation

Review of the Quench Sensitivity of Aluminium Alloys: Analysis of the Kinetics and Nature of Quench-Induced Precipitation

Dissolution and precipitation of copper-rich phases during heating and cooling of precipitation-hardening steel X5CrNiCuNb16-4 (17-4 PH)

Continuous Heating Dissolution and Continuous Cooling Precipitation Diagrams of a Nickel-Titanium Shape Memory Alloy

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