Microstructure and Precipitation Behavior of Nb, Ti Complex Microalloyed Steel Produced by Compact Strip Processing

Wang, Ruizhen; García, C. I.; Meng, Hua; Cho, K.; Zhang, Hongtao; DeArdo, A. J.

doi:10.2355/isijinternational.46.1345

Cited by 74 publications

(37 citation statements)

References 11 publications

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“…The dislocation densities reported in the literature for different microstructures differ considerably. For ferritic phases, a wide range of dislocation density values have been proposed, from very low dislocation density of 10 12 m −2 [12] to a higher ρ of 2.5 × 10 14 m −2 [13]. In the present study, the microstructures observed after a coiling at 700 • C contain secondary phases (MA microconstituent and pearlite) apart from polygonal ferrite.…”

Section: Dislocation Densitymentioning

confidence: 69%

Evaluating Strengthening and Impact Toughness Mechanisms for Ferritic and Bainitic Microstructures in Nb, Nb-Mo and Ti-Mo Microalloyed Steels

Larzabal

Isasti

Rodríguez-Ibabe

et al. 2017

Metals

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Low carbon microalloyed steels show interesting commercial possibilities by combining different "micro"-alloying elements when high strength and low temperature toughness properties are required. Depending on the elements chosen for the chemistry design, the mechanisms controlling the strengths and toughness may differ. In this paper, a detailed characterization of the microstructural features of three different microalloyed steels, Nb, Nb-Mo and Ti-Mo, is described using mainly the electron backscattered diffraction technique (EBSD) as well as transmission electron microscopy (TEM). The contribution of different strengthening mechanisms to yield strength and impact toughness is evaluated, and its relative weight is computed for different coiling temperatures. Grain refinement is shown to be the most effective mechanism for controlling both mechanical properties. As yield strength increases, the relative contribution of precipitation strengthening increases, and this factor is especially important in the Ti-Mo microalloyed steel where different combinations of interphase and random precipitation are detected depending on the coiling temperature. In addition to average grain size values, microstructural heterogeneity is considered in order to propose a new equation for predicting ductile-brittle transition temperature (DBTT). This equation considers the wide range of microstructures analyzed as well as the increase in the transition temperature related to precipitation strengthening.

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Section: Dislocation Densitymentioning

confidence: 69%

Evaluating Strengthening and Impact Toughness Mechanisms for Ferritic and Bainitic Microstructures in Nb, Nb-Mo and Ti-Mo Microalloyed Steels

Larzabal

Isasti

Rodríguez-Ibabe

et al. 2017

Metals

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“…For example, in a steel containing 0.044C-0.25Mo-0.0554Nb-0.014Ti, the ferrite grain refinement, solid solution strengthening, and work hardening together contributed up to 65 pct to the yield stress, and the precipitation and transformation (presence of bainite) strengthening contributed 35 pct. [12] In another example, in a steel containing 0.064C-0.0625Nb-0.0435Ti the grain refinement, solid solution strengthening and work hardening together contributed up to 96 pct to the yield stress, and only 4 pct was the contribution from precipitation strengthening, [13] which could be explained by a lower microalloying element content compared to that in. [12] However, in a steel containing 0.06C-0.08Nb-0.07Ti the grain refinement, solid solution strengthening and work hardening together contributed 67 pct to the yield stress, and the remaining 33 pct was the contribution from precipitation strengthening, [14] which is more than 8 times higher compared to that reported in, [13] although the microalloying element content increased by only 0.044 wt pct.…”

Section: Introductionmentioning

confidence: 99%

Strengthening Mechanisms in Thermomechanically Processed NbTi-Microalloyed Steel

Kostryzhev

Marenych

Killmore³

et al. 2015

Metall Mater Trans A

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The effect of deformation temperature on microstructure and mechanical properties was investigated for thermomechanically processed NbTi-microalloyed steel with ferrite-pearlite microstructure. With a decrease in the finish deformation temperature at 1348 K to 1098 K (1075 °C to 825 °C) temperature range, the ambient temperature yield stress did not vary significantly, work hardening rate decreased, ultimate tensile strength decreased, and elongation to failure increased. These variations in mechanical properties were correlated to the variations in microstructural parameters (such as ferrite grain size, solid solution concentrations, precipitate number density and dislocation density). Calculations based on the measured microstructural parameters suggested the grain refinement, solid solution strengthening, precipitation strengthening, and work hardening contributed up to 32 pct, up to 48 pct, up to 25 pct, and less than 3 pct to the yield stress, respectively. With a decrease in the finish deformation temperature, both the grain size strengthening and solid solution strengthening increased, the precipitation strengthening decreased, and the work hardening contribution did not vary significantly. The effect of deformation temperature on microstructure and mechanical properties was investigated for thermomechanically processed NbTi-microalloyed steel with ferrite-pearlite microstructure. With a decrease in the finish deformation temperature at 1348 K to 1098 K (1075°C to 825°C) temperature range, the ambient temperature yield stress did not vary significantly, work hardening rate decreased, ultimate tensile strength decreased, and elongation to failure increased. These variations in mechanical properties were correlated to the variations in microstructural parameters (such as ferrite grain size, solid solution concentrations, precipitate number density and dislocation density). Calculations based on the measured microstructural parameters suggested the grain refinement, solid solution strengthening, precipitation strengthening, and work hardening contributed up to 32 pct, up to 48 pct, up to 25 pct, and less than 3 pct to the yield stress, respectively. With a decrease in the finish deformation temperature, both the grain size strengthening and solid solution strengthening increased, the precipitation strengthening decreased, and the work hardening contribution did not vary significantly.

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“…Fine and abundant Ag3Sn hinders the movement of dislocation and increases creep properties [32]. In order to analyze quantitatively the mechanical strength variation by precipitate, Equations (4) and (5) were used as follows [33]:…”

Section: Discussionmentioning

confidence: 99%

The Effect of Eutectic Structure on the Creep Properties of Sn-3.0Ag-0.5Cu and Sn-8.0Sb-3.0Ag Solders

Park

Bang

et al. 2017

Metals

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Solder joints are the main weak points of power modules used in harsh environments. For the power module of electric vehicles, the maximum operating temperature of a chip can reach 175 • C under driving conditions. Therefore, it is necessary to study the high-temperature reliability of solder joints. This study investigated the creep properties of Sn-3.0Ag-0.5Cu (SAC305) and Sn-8.0Sb-3.0Ag (SSA8030) solder joints. The creep test was conducted at 175 and 190 • C with the application of 2.45 MPa. The SAC305 solder had superior creep properties to those of SSA8030 solder at 175 • C and at largely the same homologous temperature (T H~0 .91 for SAC305 and T H~0 .92 for SSA8030). Both solders had primary β-Sn and a eutectic mixture of β-Sn and Ag 3 Sn. Compared to SSA8030, the SAC305 solder contained~10% more eutectic structure and contained Ag 3 Sn that was 3 times smaller and more round in shape. Furthermore, the SSA8030 solder precipitated SnSb in an elongated fiber shape (1-50 µm in size) after the creep test. Coarse and elongated Ag 3 Sn and SnSb of the SSA8030 solder negatively affected crack propagation in the dislocation creep region and decreased the creep resistance.

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Microstructure and Precipitation Behavior of Nb, Ti Complex Microalloyed Steel Produced by Compact Strip Processing

Cited by 74 publications

References 11 publications

Evaluating Strengthening and Impact Toughness Mechanisms for Ferritic and Bainitic Microstructures in Nb, Nb-Mo and Ti-Mo Microalloyed Steels

Evaluating Strengthening and Impact Toughness Mechanisms for Ferritic and Bainitic Microstructures in Nb, Nb-Mo and Ti-Mo Microalloyed Steels

Strengthening Mechanisms in Thermomechanically Processed NbTi-Microalloyed Steel

The Effect of Eutectic Structure on the Creep Properties of Sn-3.0Ag-0.5Cu and Sn-8.0Sb-3.0Ag Solders

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