Effect of differences in grain size on the mechanical properties of steel 18Kh2N4MA

Gulyaev, A. P.; Serebrennikov, L. N.

doi:10.1007/bf00700803

Cited by 7 publications

(6 citation statements)

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“…The mechanical properties of materials displaying a bimodal austenite grain size distribution could be degraded, and some examples of such a situation have been already reported. 1) The study of the HAZ to this respect is an important issue in welding. 2) Thus, it is important to control austenite annealing conditions so as to avoid heterogeneities in grain size.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous Austenite Grain Growth in ASTM A213–T91 Steel

2007

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Heterogeneous grain growth during austenitization in ASTM A213-T91 steel has been studied using a Gleeble 3500 thermomechanical simulator. Starting from a uniform, fine austenite grain size distribution after 1 min austenite holding time, a heterogeneous austenite grain size distribution was observed after 15 min austenite holding time at 1 060°C and 1 080°C. The state of precipitation of second phase particles was studied in detail as a function of austenitization time. The particle size distribution changed towards a bimodal feature as a function of time whereas the count frequency of the coarse precipitates increased and the count frequency of fine precipitates diminished with time. V-rich precipitates were dissolved during austenitization and only Nb-rich particles remained after 15 min austenitizing time. The experimental observations on the evolution of the austenite grain size distribution are rationalized on the basis of the Gladman's approach to abnormal grain growth.

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“…The mechanical properties of materials displaying a bimodal austenite grain size distribution could be degraded, and some examples of such a situation have been already reported. 1) The study of the HAZ to this respect is an important issue in welding. 2) Thus, it is important to control austenite annealing conditions so as to avoid heterogeneities in grain size.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous Austenite Grain Growth in ASTM A213–T91 Steel

2007

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“…[23][24][25] In cases in which heterogeneity occurs and/or a bimodal AGSD is present, the mechanical properties of steels could be degraded, and some examples of such a situation have been already reported. 26 In a previous contribution, 27 we have reported the austenitising conditions (heating rate to austenite and initial metallurgical condition) under which homogeneous or heterogeneous AGSDs are developed during austenite annealing at fixed temperature and holding time in an ASTM A213-T91 steel. In that work, we focused our attention on the presence of a few very large austenite grains in a small to medium sized matrix, with no further analysis of the AGSD itself.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous austenite grain growth in ASTM A213 Grade T91 steels: Analysis of austenitic grain size distribution using kernel density estimation methodology

Zavaleta-Gutierrez

Toda‐Caraballo

Luppo

et al. 2014

Materials Science and Technology

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The present work studies, using statistical methods, the features of austenite grain size distributions (AGSDs) obtained in an ASTM A213-T91 steel by applying two-step thermal cycles, namely, thermal treatment at tempering temperature+‘ in situ’ austenitisation. Changes in AGSD were produced by varying the holding time at tempering temperature and the heating rate to austenite. The application of different thermal cycle conditions induced two main characteristics in the AGSDs, i.e. the growth of a few very large grains in a matrix of small to medium sized grains, that is, heterogeneous grain size, and a bimodal grain size distribution in that matrix. Statistical techniques were used to describe the resulting AGSDs and to investigate a possible correlation between bimodality and heterogeneity. The characterisations have been carried out using the kernel density estimation (KDE) technique to compute the underlying statistical distribution, and then applying a significance test able to assess whether or not bimodality, if detected with KDE, is statistically significant. Results indicate that bimodality is evidenced for the higher heating rates to austenite and is very likely related to the development of the heterogeneous grain size structure.

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“…The mechanical properties of materials displaying a bimodal austenite grain size distribution could be degraded, and some examples of such a situation have been already reported. 11,12,13 Therefore, it is important to control the thermal cycle parameters in processes requiring stages of austenite holding so as to avoid heterogeneities in grain size. In this sense, the influence of the heating rate V H to austenite in the austenitic grain size distribution, particularly, in the formation of a heterogeneous grain size structure, has been reported in the literature referred to carbon steels, 7,14 microalloyed steels containing Ti, and V and Nb, 8,9,10,11,15,18 ferritic-martensitic 9% Cr 19,20,21 and martensitic 14%Cr 22 steels .…”

Section: Introductionmentioning

confidence: 99%

“…11,12,13 Therefore, it is important to control the thermal cycle parameters in processes requiring stages of austenite holding so as to avoid heterogeneities in grain size. In this sense, the influence of the heating rate V H to austenite in the austenitic grain size distribution, particularly, in the formation of a heterogeneous grain size structure, has been reported in the literature referred to carbon steels, 7,14 microalloyed steels containing Ti, and V and Nb, 8,9,10,11,15,18 ferritic-martensitic 9% Cr 19,20,21 and martensitic 14%Cr 22 steels . In some cases, a critical value for the heating rate has been found, above which a heterogeneous austenite grain size distribution is developed for fixed conditions of austenite temperature and holding time.…”

Section: Introductionmentioning

confidence: 99%

“…Heterogeneous or abnormal grain growth in austenite may be a non-wished result of manufacturing processes implying austenitisation. The mechanical properties of materials displaying a bimodal austenite grain size distribution could be degraded, and some examples of such a situation have been already reported 11,12,13. Therefore, it is important to control the thermal cycle parameters in processes requiring stages of austenite holding so as to avoid heterogeneities in grain size.…”

Section: Introductionmentioning

confidence: 99%

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Heterogeneous austenite grain growth in martensitic 9cr steel: Coupled influence of initial metallurgical state and heating rate

Zavaleta-Gutierrez

Luppo

Danón

et al. 2013

Materials Science and Technology

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The coupled influence of the initial metallurgical state and the heating rate to austenite on the occurrence of heterogeneous grain growth during austenitization of an ASTM A213 -T91 steel has been studied. To that aim, two-step thermal cycles were designed. In the first step, different starting metallurgical conditions were obtained by treating the as-received material at 780 C for increasing times up to 6 hours. In the second step, "in situ" austenitization was performed by heating to austenite at rates of 1, 30 and 50 ºC/s and then holding at 1050 ºC for 30'.Two types of austenite grain structures were obtained after austenitization, namely, homogeneous and heterogeneous. The homogeneous structure was characterized by a smooth size distribution of approximately equiaxed, normally grown grains. The heterogeneous structure, instead, exhibited the exaggerated growth of a few austenite grains embedded in a small to medium-sized "matrix".For the 1 ºC/s heating rate and all of the initial metallurgical states, only homogeneous grain growth was observed, whereas for the 50 ºC/s heating rate only heterogeneous grain growth was observed regardless the starting metallurgical condition. Instead, the occurrence of homogeneous or heterogeneous grain growth after heating at 30 ºC/s was observed to be a function of the time of previous tempering. Some explanations of the phenomenon are advanced taking into account the precipitation state of second phases.

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Effect of differences in grain size on the mechanical properties of steel 18Kh2N4MA

Cited by 7 publications

References 1 publication

Heterogeneous Austenite Grain Growth in ASTM A213–T91 Steel

Heterogeneous Austenite Grain Growth in ASTM A213–T91 Steel

Heterogeneous austenite grain growth in ASTM A213 Grade T91 steels: Analysis of austenitic grain size distribution using kernel density estimation methodology

Heterogeneous austenite grain growth in martensitic 9cr steel: Coupled influence of initial metallurgical state and heating rate

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