Influence of heating rate on the alpha?gamma-transformation critical temperatures in 40Kh steel

Nikishov, N. A.; Sokolov, Andrey M.; Ul'yanov, V. G.

doi:10.1007/bf00774833

Cited by 2 publications

(2 citation statements)

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“…Repeated measurements confirmed this trend, not only for these steels, but also other industrial melts of the same steels. This is somewhat consistent with the work of Nikishov et al, who found a decrease in A c3 with increasing heating rate in the range of 0–15 °C s −1 in a non‐microalloyed steel 40 Kh (plain C steel with 0.4 wt% C) with a martensitic starting microstructure. Similarly, Law and Edmonds found in the steel Fe–1V–0.2C steel with 0.038 wt% Nb that the A c3 slightly decreases or remains constant when the heating rate is raised from 0.05 to 0.5 °C s −1 , and then continuously increases with further increase in heating rate.…”

Section: Methodssupporting

confidence: 92%

Study of Structural Inheritance of Austenite in Nb‐Microalloyed 18CrNiMo7–6 Steel

Sharma

Bleck

2018

steel research int.

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Structural inheritance (SI) is a phenomenon in which the newly formed austenite retains the prior austenite grain size, shape, and orientation of the previous martensitic, bainitic, or even tempered martensitic microstructure. The present work studies SI in 18CrNiMo7-6 steel with 0.08 wt% Nb and compares it with that in a similar but non-microalloyed steel, 20MnCr5. While a coarse prior austenite grain size (PAGS) and a martensitic, bainitic, or tempered martensitic microstructure are found to be the pre-requisites for the manifestation of SI, heating rate, tempering, and steel composition equally influence its occurrence. The larger the PAGS, the easier is the production of SI. SI occurs with the greatest ease in a martensitic microstructure. Tempering is found to retard SI. The ease of occurrence of SI is this: as-quenched martensite>bainite>tempered martensite. The effect of heating rate is non-monotonic, in that, SI is more likely on very slow (0.05 C s À1 ) or very fast heating (50 C s À1 ; 100 C s À1 ) compared with intermediate heating rates (0.5 C s À1 ; 5 C s À1 ). Nb increases the tendency for SI, but a steel without Nb can also exhibit SI.

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Section: Methodssupporting

confidence: 92%

Study of Structural Inheritance of Austenite in Nb‐Microalloyed 18CrNiMo7–6 Steel

Sharma

Bleck

2018

steel research int.

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“…It had been suggested that the original microstructure, ferritic-pearlitic and martensite, affected reverse transformation by increasing or decreasing transformation temperature of A c1 and A c3 , 8 while the morphology and grain size of initial phase also had a notable influence on the transformation rate. 9 Besides, the addition of alloys such as Mn, Si and Cr retarded austenite reformation.…”

Section: Introductionmentioning

confidence: 99%

In situ observation of bainite to austenite transformation of microalloyed high strength steel during simulated welding cycle

Lei

Wang

et al. 2014

Science and Technology of Welding and Joining

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A confocal scanning laser microscope, equipped with a high temperature stage, was used for in-situ observation of the bainite-to-austenite transformation in a micro-alloyed ultra-high strength steel. Austenite grain growth was observed and measured directly from 1040 °C to the peak temperature of 1340 °C during the heating process, as well as the subsequent cooling down to 1040 °C. The grain growth rate versus temperature was analyzed. It was demonstrated that the austenite grains grew up simultaneously by means of grain boundary migration and "grain swallowing" phenomena. The variation in grain growth rate was attributed to the presence of impeding precipitates e.g. carbonitrides Nb,Ti(C,N). The work also showed that coarsening and/or dissolution of carbonitride precipitates, above a certain temperature, led to a fast grain growth. The in-situ observation by confocal scanning laser microscope can provide valuable information on the austenite reformation and final microstructure of weldments.

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Influence of heating rate on the alpha?gamma-transformation critical temperatures in 40Kh steel

Cited by 2 publications

References 1 publication

Study of Structural Inheritance of Austenite in Nb‐Microalloyed 18CrNiMo7–6 Steel

Study of Structural Inheritance of Austenite in Nb‐Microalloyed 18CrNiMo7–6 Steel

In situ observation of bainite to austenite transformation of microalloyed high strength steel during simulated welding cycle

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