H. Keshmiri
材料科学技术（英文）
Duplex stainless steels (DSS) with ferritic{austenitic microstructures offer good combination of resistance to pitting corrosion and high strength that are not concomitantly attainable using conventional single phase austenitic or ferritic stainless steels. The DSS used in this investigation was 2205 alloy having a stable microstructure consisting of about 45% ferrite and 55% austenite at ambient temperature. In order to investigate aging behavior of this steel and the influences on mechanical properties, different aging treatments were conducted at temperatures of 350−950°C for various aging time of 15, 30, 60 and 180 min. The aged specimens were subjected to impact testing and hardness measurements. Finally, the changes in microstructure due to aging were studied by optical and scanning electron microscopy. The results showed that aging at temperatures lower than 550°C for different time had negligible effects on mechanical properties. Besides, no considerable changes in term of precipitation of harmful intermetallic particles were observed in microstructure below this temperature. However, a critical temperature range, 550−650 °C, was introduced here. Aging in this range led to a significant decrease in toughness and notable increase in hardness. The formation of intermetallic phases such as σ was recognized as the major reason for the observed changes.
关键词:
Duplex stainless steel
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null
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null
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null
A. Momeni K. Dehghani
材料科学技术（英文）
In this research, aging treatments at temperatures of 800 and 900°C for different aging time of 5{60 min were conducted on solution treated as well as hot worked samples of 2205 dual phase stainless steel. The effect of aging treatment on precipitation of intermetallic phases was investigated in undeformed specimens and those subjected to hot deformation with different strain rates of 0.001−1 s−1. It was found that σ precipitation increased by hot working. It was also concluded that the volume fraction of phase increased with deformation temperature and decreased with strain rate. The precipitation of intermetallic phases (i.e. σ and χ) was analyzed by an Avrami-type kinetics equation of %(σ+χ)=A(1-exp(-ktn)) and the values of n and ln k were estimated for different thermomechanical regimes. The values of n were assessed to increase from 0.4 to 1 with strain rate in the studied range. Otherwise, It was also understood that ln k decreased with strain rate. Microstructural observations by means of optical microscopy and scanning electron microscopy showed that σ particles mostly nucleated at the ferrite-austenite interfaces. But no sign of Â-phase could be seen. This fortified the idea of certain literature that Â-phase always forms at early stages of aging and consumes through the precipitation of σ.
关键词:
Duplex stainless steel
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Hot Working
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Sigma Phase
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Secondary Phase
A. Momeni K. Dehghani
材料科学技术（英文）
In this research, aging treatments at temperatures of 800 and 900°C for different aging time of 5{60 min were conducted on solution treated as well as hot worked samples of 2205 dual phase stainless steel. The effect of aging treatment on precipitation of intermetallic phases was investigated in undeformed specimens and those subjected to hot deformation with different strain rates of 0.001−1 s−1. It was found that σ precipitation increased by hot working. It was also concluded that the volume fraction of phase increased with deformation temperature and decreased with strain rate. The precipitation of intermetallic phases (i.e. σ and χ) was analyzed by an Avrami-type kinetics equation of %(σ+χ)=A(1-exp(-ktn)) and the values of n and ln k were estimated for different thermomechanical regimes. The values of n were assessed to increase from 0.4 to 1 with strain rate in the studied range. Otherwise, It was also understood that ln k decreased with strain rate. Microstructural observations by means of optical microscopy and scanning electron microscopy showed that σ particles mostly nucleated at the ferrite-austenite interfaces. But no sign of Â-phase could be seen. This fortified the idea of certain literature that Â-phase always forms at early stages of aging and consumes through the precipitation of σ.
关键词:
Duplex stainless steel
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Hot Working
,
Sigma Phase
,
Secondary Phase
Juliang Xu
材料科学技术（英文）
The critical pitting temperature (CPT) of 2101 lean duplex stainless steel (DSS) in 1 mol/L NaCl was investigated. Potentiostatic electrochemical noise (EN) technique coupled with scanning electron microscopy (SEM) was used to study the corrosion process of 2101 DSS at different temperatures (15, 25, 28, and 35 °C) from below CPT to above CPT. The EN data were analyzed by wavelet technique based on orthogonal db4 wavelet. The results showed that, the patterns of current noises were different at different temperatures. The characteristics of energy distribution plot (EDP) obtained from wavelet analysis technique can be used as "fingerprints" of EN signal and can be used to interpret the corrosion process. With increasing solution temperature, the
maximum relative energy defined in EDP changed from the region of crystal series coefficients with smaller scales through middle scales to larger scales, which indicated the process of initiation, propagation and growth into stable pitting of metastable pitting. The results were well confirmed by the corresponding morphologies.
关键词:
Duplex stainless steel
Pingli MAO
,
Ke YANG
,
Guoyue SU
材料科学技术（英文）
The hot deformation behavior of an as-cast 0Cr17Mn14Mo2N duplex stainless steel has been studied by hot compression test at the temperature range from 1000℃ to 1200℃, and the strain rates are 0.1 s-1, 1 s-1 and 5 s-1, respectively. It was found that during hot deformation there is only dynamic recovery taking place within the δ-ferrite phase, but the γ-austenite phase undergoes dynamic recrystallization. The activation energy of the steel for hot compression is estimated to be 480 kJ/mol.
关键词:
Hot deformation
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null
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