Influence of original microstructure on the transformation behavior and mechanical properties of ultra-high-strength TRIP-aided steel

Yin, Haiqing; Zhang, Aimin; Zhao, Zhengzhi; Xiao, Li; Li, Shuang-jiao; Hu, Hao; Xia, Weiguang

doi:10.1007/s12613-015-1070-6

Cited by 20 publications

(12 citation statements)

References 15 publications

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“…The other more important factors are the RA fraction and its stability; as was shown previously, to maximise the TRIP effect and enhance mechanical properties an increased RA fraction with medium stability would be required [13,16,18,31]. The amount of RA observed here ranged from 0.023 to 0.045, which was much lower than the ~ 0.05 -0.2 fraction usually present in this kind of conventional low alloyed TRIP steels [12,13,15].…”

Section: The Approaches To Improve Mechanical Propertiesmentioning

confidence: 46%

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Microstructures and mechanical properties of TRIP steel produced by strip casting simulated in the laboratory

Xiong

Kostryzhev

Saleh

et al. 2016

Materials Science and Engineering: A

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Conventional transformation induced plasticity (TRIP) steel (0.17C-1.52Si-1.61Mn-0.03Al, wt%) was produced via strip casting technology simulated in the laboratory. Effects of holding temperature, holding time and cooling rate on ferrite formation were studied via analysis of the continuous cooling transformation diagram obtained here. A typical microstructure for conventional TRIP steels consisting of ~ 0.55 fraction of polygonal ferrite with bainite, retained austenite and martensite was obtained. However, coarse prior austenite grain size of ~80 μm led to large polygonal ferrite grain size of ~17 μm, coarse second phase regions of ~21 μm size, small amount of retained austenite (0.02-0.045) and the presence of Widmanstätten ferrite. Optimisation of the microstructure-property relationship was reached via a variation in the isothermal bainite transformation temperature. The highest retained austenite fraction of 0.045±0.003 with medium carbon content of 1.23±0.01 wt% was obtained after holding at 400 °C, resulting in the highest ultimate tensile strength of 590±35 MPa and largest total elongation of 0.27±0.05. The presence of TRIP effect in the studied steel was revealed through the analysis of strain hardening exponent and modified Crussard-Jaoul model. Effect of processing parameters on retained austenite retention and stress-strain behaviour was discussed. Conventional transformation induced plasticity (TRIP) steel (0.17C-1.52Si-1.61Mn-0.03Al, wt. %) was produced via strip casting technology simulated in the laboratory. Effects of holding temperature, holding time and cooling rate on ferrite formation were studied via analysis of the continuous cooling transformation diagram obtained here. A typical microstructure for conventional TRIP steels consisting of ~ 0.55 fraction of polygonal ferrite with bainite, retained austenite and martensite was obtained. However, coarse prior austenite grain size of ~ 80 μm led to large polygonal ferrite grain size of ~ 17 μm, coarse second phase regions of ~ 21 μm size, small amount of retained austenite (0.02 -0.045) and the presence of Widmanstätten ferrite. Optimisation of the microstructure-property relationship was reached via a variation in the isothermal bainite transformation temperature. The highest retained austenite fraction of 0.045±0.003 with medium carbon content of 1.23±0.01 wt. % was obtained after holding at 400 °C, resulting in the highest ultimate tensile strength of 590±35 MPa and largest total elongation of 0.27±0.05. The presence of TRIP effect in the studied steel was revealed through the analysis of strain hardening exponent and modified Crussard -Jaoul model. Effect of processing parameters on retained austenite retention and stress-strain behaviour was discussed.

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Section: The Approaches To Improve Mechanical Propertiesmentioning

confidence: 46%

“…Similar observations were reported in Refs. [31,48]. The rate of strain hardening exponent variation in the T 400 sample was lower than that in the T 450 sample.…”

Section: Ebsd and Apt Analysis Of The T 400 Samplementioning

confidence: 78%

Microstructures and mechanical properties of TRIP steel produced by strip casting simulated in the laboratory

Xiong

Kostryzhev

Saleh

et al. 2016

Materials Science and Engineering: A

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“…Figure 6 shows variations of retained austenite stability factor k as a function of true strain e which is between 0% and fracture in conventional and I-Q&P steels. k is defined by the following equation [22]:…”

Section: Retained Austenite Characterizationmentioning

confidence: 99%

Effect of Heat Treatment on Microstructure and Mechanical Properties of Quenching and Partitioning Steel

Sun

Zhang

Ding

et al. 2017

Acta Metall. Sin. (Engl. Lett.)

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In order to investigate the effect of microstructural characterization on the mechanical properties and retained austenite stability, a different type of quenching and partitioning steel (I-Q&P) through intercritical annealing before the quenching and partitioning process was designed, which can realize lamellar intercritical microstructure compared to the conventional quenching and partitioning (Q&P) process. The morphology of ferrite and martensite/retained austenite is lamellar in the I-Q&P steel while it is equiaxed after being heat-treated by conventional Q&P process. The I-Q&P steel is proved to have better formability and mechanical properties than conventional Q&P steel, which is due to the highervolume fraction of retained austenite in the I-Q&P steel and confirmed by electron backscattering diffraction patterns and X-ray diffraction. Furthermore, the stability of retained austenite in I-Q&P steel is also higher than that in conventional Q&P steel, which is investigated by tensile tests and differential scanning calorimetry.

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“…It was estimated that 10% of weight reduction generally may bring about 5% less of gas consumption [1]. Therefore, these years light metal materials such as Al alloys and Mg alloys have been increasingly used in automobile industry.…”

Section: Introductionmentioning

confidence: 99%

Effects of Ar and He on Microstructures and Properties of Laser Welded 800MPa TRIP Steel

et al. 2018

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Abstract. Fiber laser welding of cold rolled TRIP steel (transformation Induced Plasticity steel) sheet with tensile strength of 820MPa and thickness of 1.4mm was carried out using shielding gases Ar and He, respectively. For the same laser power and welding speed, the effects of different shielding gases on penetration and bead section morphologies were investigated. The microstructures and properties of the TRIP steel joints were also studied. The investigation showed that higher penetration and lower porosity could be obtained under shielding gas He using the same laser power and welding speed. The microstructures of the TRIP joint mainly included martensite and retained austenite. But the joint microhardness and tensile strength were higher under the shielding gas He. The tensile strength of the welded joint perpendicular to the weld line was equal to that of the base metal. But the tensile strength of the joint parallel with the weld line was higher than that of the base metal. The plasticity and formability of the welded joint were impaired due to the formation of martensite in the weld metal.

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Influence of original microstructure on the transformation behavior and mechanical properties of ultra-high-strength TRIP-aided steel

Cited by 20 publications

References 15 publications

Microstructures and mechanical properties of TRIP steel produced by strip casting simulated in the laboratory

Microstructures and mechanical properties of TRIP steel produced by strip casting simulated in the laboratory

Effect of Heat Treatment on Microstructure and Mechanical Properties of Quenching and Partitioning Steel

Effects of Ar and He on Microstructures and Properties of Laser Welded 800MPa TRIP Steel

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