Optimum properties of quenching and partitioning steels achieved by balancing fraction and stability of retained austenite

Liu, L.; He, Binbin; Cheng, Guan-Ju; Yen, Hung‐Wei; Huang, Mingxin

doi:10.1016/j.scriptamat.2018.02.035

Cited by 123 publications

(43 citation statements)

References 21 publications

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“…Accordingly, the prior austenite grains were divided into the smaller retained austenite grains. Similar conclusions were reported in a previous paper [30]. In other words, the more primary martensite, the smaller the retained austenite grain size.…”

Section: Optimum Quenching Temperaturesupporting

confidence: 92%

A Study of the Optimum Quenching Temperature of Steels with Various Hot Rolling Microstructures after Cold Rolling, Quenching and Partitioning Treatment

Chen

Liang

Kang

et al. 2018

Metals

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Quenching and partitioning (Q&P) processes were applied to a cold-rolled high strength steel (0.19C-1.26Si-2.82Mn-0.92Ni, wt %). The effects of the prior hot-rolled microstructure on the optimum quenching temperature of the studied steels were systematically investigated. The microstructure was analyzed by means of transmission electron microscope (TEM), electron backscatter diffraction (EBSD) and X-ray diffraction (XRD). Compared with the ferrite pearlite mixture matrix, the lower martensite start (Ms) temperature and smaller prior austenite grain size in the cold-rolled martensite matrix are the main reasons for the optimum quenching temperature shifting to a lower temperature in the Q&P steels. We found that an empirical formula that only considers the influence of the alloy composition in the calculation of the Ms temperature will cause a certain interference to the pre-determined optimum quenching temperature of the Q&P steel.

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Section: Optimum Quenching Temperaturesupporting

confidence: 92%

A Study of the Optimum Quenching Temperature of Steels with Various Hot Rolling Microstructures after Cold Rolling, Quenching and Partitioning Treatment

Chen

Liang

Kang

et al. 2018

Metals

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“…It is generally believed that a large austenite volume fraction with optimized stability is desirable for developing strong and ductile steel for automotive application [ 180 , 181 ], which can be achieved by controlling the intrinsic factors (chemical compositions, dislocations, grain size, and morphology) through thermal-mechanical processing. The chemical compositions play a pivotal role in controlling the austenite stability at room temperature, which is assisted by other intrinsic factors.…”

Section: Alloy Design Strategiesmentioning

confidence: 99%

On the Factors Governing Austenite Stability: Intrinsic versus Extrinsic

2020

Materials

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In this review, we separate the different governing factors on austenite stability into intrinsic and extrinsic factors, depending on the domain defined by austenite grain boundaries. The different measuring techniques on the effectiveness of the governing factors in affecting the austenite stability are discussed. On the basis of the austenite stability, a new alloy design strategy that involves the competition between the intrinsic and extrinsic factors to control the transformation-induced plasticity (TRIP) effect to realize the stronger the more ductile steel is proposed. The present review may provide new insights into the development of novel thermal-mechanical processing to advance the mechanical properties of steels for industrial applications.

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“…As a third-generation advanced high strength steel (AHSS), quenching and partitioning (Q&P) steels exhibit an excellent combination of strength and ductility for automotive body lightweighting [1][2][3][4][5][6]. The production of ultimate tensile strength and total elongation has reached over 30,000 MPa % in state-of-the-art Q&P steels [7][8][9]. Up to now, some Q&P steels have already been commercialized in the automotive industry, such as QP980, with ultimate tensile strength over 980 MPa and total elongation over 20% [1].…”

Section: Introductionmentioning

confidence: 99%

“…The influence of retained austenite has two aspects. On the one hand, the metastable retained austenite transforms into martensite under external stress and strain, producing the transformation induced plasticity (TRIP) effect [4,7]. The TRIP effect guarantees the continuous work hardening of Q&P steels during deformation, contributing to the strength-ductility balance [4,21], which could also benefit the hydrogen embrittlement resistance.…”

Section: Introductionmentioning

confidence: 99%

“…On the contrary, in ultra-high strength Q&P steels, hydrogen embrittlement has been rarely studied despite the increased risk. Additionally, differently from QP980, the microstructure of ultra-high strength Q&P steels contains a larger fraction of retained austenite and almost full martensite matrix [1,7,17]. Thus, more studies should be conducted, and new methods should be developed to enhance the hydrogen embrittlement resistance of ultra-high strength Q&P steels.…”

Section: Introductionmentioning

confidence: 99%

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Improving Hydrogen Embrittlement Resistance of Hot-Stamped 1500 MPa Steel Parts That Have Undergone a Q&P Treatment by the Design of Retained Austenite and Martensite Matrix

Wang

Huang

2020

Metals

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Hydrogen embrittlement is one of the largest obstacles against the commercialisation of ultra-high strength quenching and partitioning (Q&P) steels with ultimate tensile strength over 1500 MPa, including the hot stamped steel parts that have undergone a Q&P treatment. In this work, the influence of partitioning temperature on hydrogen embrittlement of ultra-high strength Q&P steels is studied by pre-charged tensile tests with both dog-bone and notched samples. It is found that hydrogen embrittlement resistance is enhanced by the higher partitioning temperature. Then, the hydrogen embrittlement mechanism is analysed in terms of hydrogen, retained austenite, and martensite matrix. Thermal desorption analysis (TDA) shows that the hydrogen trapping properties are similar in the Q&P steels, which cannot explain the enhancement of hydrogen embrittlement resistance. On the contrary, it is found that the relatively low retained austenite stability after the higher temperature partitioning ensures more sufficient TRIP effect before hydrogen-induced fracture. Additionally, dislocation recovery and solute carbon depletion at the higher partitioning temperature can reduce the flow stress of the martensite matrix, improving its intrinsic toughness and reducing its hydrogen sensitivity, both of which result in the higher hydrogen embrittlement resistance.

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Optimum properties of quenching and partitioning steels achieved by balancing fraction and stability of retained austenite

Cited by 123 publications

References 21 publications

A Study of the Optimum Quenching Temperature of Steels with Various Hot Rolling Microstructures after Cold Rolling, Quenching and Partitioning Treatment

A Study of the Optimum Quenching Temperature of Steels with Various Hot Rolling Microstructures after Cold Rolling, Quenching and Partitioning Treatment

On the Factors Governing Austenite Stability: Intrinsic versus Extrinsic

Improving Hydrogen Embrittlement Resistance of Hot-Stamped 1500 MPa Steel Parts That Have Undergone a Q&P Treatment by the Design of Retained Austenite and Martensite Matrix

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