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Title: Cryogenic deformation microstructures of 32Mn-7Cr-1Mo-0.3N austenitic steels

Abstract

The cryogenic deformation microstructures of impact and tensile specimens of 32Mn-7Cr-1Mo-0.3N austenitic steel were investigated using light microscopy and transmission electron microscopy. The results show that the deformation microstructures of the impact specimens are mainly composed of stacking faults, network dislocation, slip bands, and a few mechanical twins and {epsilon}-martensite. These microstructures cross with each other in a crystal angle. The deformation microstructures of the tensile specimens consist only of massive slip bands, in which a few mechanical twins and {epsilon}-martenite are located. Because of the larger plastic deformation the slip band traces become bent. All the deformation microstructures are formed on the {l_brace}111{r_brace} planes and along the <110> orientation.

Authors:
 [1];  [2];  [2];  [2];  [2]
  1. Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, QinHuang Dao 066004 (China). E-mail: rdfu@ysu.edu.cn
  2. Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, QinHuang Dao 066004 (China)
Publication Date:
OSTI Identifier:
20833175
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 55; Journal Issue: 4-5; Other Information: DOI: 10.1016/j.matchar.2005.07.014; PII: S1044-5803(05)00194-4; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AUSTENITIC STEELS; CHROMIUM ALLOYS; CRYSTALS; DEFORMATION; DISLOCATIONS; MANGANESE ALLOYS; MARTENSITE; MICROSTRUCTURE; MOLYBDENUM ALLOYS; PLASTICITY; STACKING FAULTS; TRANSMISSION ELECTRON MICROSCOPY

Citation Formats

Fu Ruidong, Qiu Liang, Wang Tiansheng, Wang Cunyu, and Zheng Yangzeng. Cryogenic deformation microstructures of 32Mn-7Cr-1Mo-0.3N austenitic steels. United States: N. p., 2005. Web.
Fu Ruidong, Qiu Liang, Wang Tiansheng, Wang Cunyu, & Zheng Yangzeng. Cryogenic deformation microstructures of 32Mn-7Cr-1Mo-0.3N austenitic steels. United States.
Fu Ruidong, Qiu Liang, Wang Tiansheng, Wang Cunyu, and Zheng Yangzeng. Tue . "Cryogenic deformation microstructures of 32Mn-7Cr-1Mo-0.3N austenitic steels". United States. doi:.
@article{osti_20833175,
title = {Cryogenic deformation microstructures of 32Mn-7Cr-1Mo-0.3N austenitic steels},
author = {Fu Ruidong and Qiu Liang and Wang Tiansheng and Wang Cunyu and Zheng Yangzeng},
abstractNote = {The cryogenic deformation microstructures of impact and tensile specimens of 32Mn-7Cr-1Mo-0.3N austenitic steel were investigated using light microscopy and transmission electron microscopy. The results show that the deformation microstructures of the impact specimens are mainly composed of stacking faults, network dislocation, slip bands, and a few mechanical twins and {epsilon}-martensite. These microstructures cross with each other in a crystal angle. The deformation microstructures of the tensile specimens consist only of massive slip bands, in which a few mechanical twins and {epsilon}-martenite are located. Because of the larger plastic deformation the slip band traces become bent. All the deformation microstructures are formed on the {l_brace}111{r_brace} planes and along the <110> orientation.},
doi = {},
journal = {Materials Characterization},
number = 4-5,
volume = 55,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2005},
month = {Tue Nov 15 00:00:00 EST 2005}
}
  • In this research, the tensile properties of a Fe-32Mn-12Cr-0.4C cryogenic alloy were investigated at temperatures between {minus}196 C to 250 C. This study was intended to clarify the influence of temperature on tensile properties and to correlate the deformed microstructures with the tensile elongation. The formation of strain-induced changes, deformation twins and strain-induced {var_epsilon}-martensite, was analyzed at various temperatures. The effects of the strain-induced changes on strain hardening rate were discussed to explain the variation of tensile elongation of Fe-32Mn-12Cr-0.4C cryogenic alloy.
  • The influence of temperature cycling from room temperature to 77 K on nitrogen-alloyed austenitic stainless steels, Fe24Mn13Cr0.4N, Fe24Mn18Cr3Ni0.6N, Fe1Mn19Cr8Ni0.2N and Fe17Mn14Cr1Ni0.4N, has been studied by optical microscopy and scanning electronic microscopy (SEM). Results show that the phase transformation from austenite to {epsilon} martensite takes place due to the temperature cycling and stress concentration, whereas nitrogen can stabilize the austenitic microstructures greatly. Finally, the mechanism of the phase transformation and the structure of {epsilon} martensite are discussed in detail.
  • A comprehensive study was carried out on the strain-induced martensitic transformation, its reversion to austenite, the resultant grain refinement, and the enhancement of strength and strain-hardening ability through the transformation-induced plasticity (TRIP) effect in a commercial austenitic 304L stainless steel with emphasis on the mechanisms and the microstructural evolution. A straightforward magnetic measurement device, which is based on the measurement of the saturation magnetization, for evaluating the amount of strain-induced martensite after cold rolling and reversion annealing in metastable austenitic stainless steels was used, which its results were in good consistency with those of the X-ray diffraction (XRD) method. Amore » new parameter called the effective reduction in thickness was introduced, which corresponds to the reasonable upper bound on the obtainable martensite fraction based on the saturation in the martensitic transformation. By means of thermodynamics calculations, the reversion mechanisms were estimated and subsequently validated by experimental results. The signs of thermal martensitic transformation at cooling stage after reversion at 850 °C were found, which was attributed to the rise in the martensite start temperature due to the carbide precipitation. After the reversion treatment, the average grain sizes were around 500 nm and the nanometric grains of the size of ~ 65 nm were also detected. The intense grain refinement led to the enhanced mechanical properties and observation of the change in the work-hardening capacity and TRIP effect behavior. A practical map as a guidance for grain refining and characterizing the stability against grain growth was proposed, which shows the limitation of the reversion mechanism for refinement of grain size. - Graphical abstract: Display Omitted - Highlights: • Nano/ultrafine grained austenitic stainless steel through martensite treatment • A parameter descriptive of a reasonable upper bound on the obtainable martensite • Characterization of martensite by virtue of a new developed magnetic device • Investigation of mechanical properties and TRIP effect and the effect of grain size.« less