Application of Quenching and Partitioning (Q&amp;P) Processing to Press Hardening Steel

Seo, Eun Jung; Cho, Lawrence; Cooman, Bruno C. De

doi:10.1007/s11661-014-2316-z

Cited by 81 publications

(50 citation statements)

References 28 publications

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“…Residual ductility of press hardened parts (in service) is limited, and Q&P processing has been investigated in a hot stamping context to enhance tensile ductility of formed parts with encouraging results. 56,91 Application of Q&P to other sheet steel product areas such as hot rolled carbon 92 and stainless steel [41][42][43]93 also remain fruitful focus areas. Coil cooling may be employed in the hot strip mill to obtain carbon partitioning, 92 following controlled run-out table cooling and coiling.…”

Section: Mechanical Behaviourmentioning

confidence: 99%

Critical Assessment 7: Quenching and partitioning

Speer

Moor

Clarke

2015

Materials Science and Technology

138

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Quenching and partitioning is a relatively new heat treatment concept to generate microstructures containing retained austenite stabilised by carbon partitioning from martensite. Research on quench and partitioning has been conducted by numerous groups, and this critical assessment provides some of the authors’ perspectives on progress and understanding in the field, with particular focus on the physical metallurgy and transformation mechanisms, process variations, mechanical behaviour, and industrial implementation. While much progress has been made, the field provides rich opportunity for further understanding and development.

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Section: Mechanical Behaviourmentioning

confidence: 99%

Critical Assessment 7: Quenching and partitioning

Speer

Moor

Clarke

2015

Materials Science and Technology

138

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“…The synergetic effect of the Si and Cr additions in increasing the retained austenite volume fraction during Q&P processing was reported previously. [8,11] The microstructure of the industrially cold-rolled sheet steel prior to Q&P processing was a complex microstructure containing deformed pearlite and martensite.Q&P processing was carried out in a Ba¨hr 805 pushrod dilatometer either in vacuum or in a He atmosphere. The specimens with dimensions of 10 9 5 9 1.2 mm 3 were heated at a heating rate of +10°C/s to 1123 K (850°C), fully austenitized for 240 seconds at 1123 K (850°C) and initially quenched to a T Q temperature in the range of 423 K to 543 K (150°C to 270°C) with 293 K (20°C) increments.…”

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confidence: 99%

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confidence: 99%

Application of Quenching and Partitioning Processing to Medium Mn Steel

Seo

Cho

Cooman

2014

Metall Mater Trans A

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101

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The present work analyzes the application of quenching and partitioning processing to medium Mn steel to obtain a new type of ultra-high-strength multiphase medium Mn steel. The selection of the quench temperature makes it possible to vary the ultimate tensile strength within a range of 500 MPa. The processing leads to lowcarbon lath martensite matrix with a controlled volume fraction of retained austenite. Increasing requirements related to passenger safety and weight reduction in the automotive industry have led to the development of a first generation of advanced high strength steels (AHSS) such as dual phase and transformation-induced plasticity (TRIP) steels. Second generation austenitic high-Mn twinning-induced plasticity (TWIP) steel with a Mn content in the range of 15 to 25 wt pct exhibits an excellent combination of tensile strength (~1 GPa) and ductility (~60 pct) due to a dynamic Hall-Petch effect resulting from the gradual increase of the density of mechanical twins during deformation.[1,2] The higher alloying costs and the lower productivity associated with high-Mn TWIP steel are currently the main drivers behind the development of the intermediate and medium Mn steel. Adequate combinations of mechanical properties have been reported for intercritically annealed intermediate and medium Mn steels. Their high work-hardening rate is achieved by the TRIP effect or a combination of two plasticity-enhancing mechanisms, the TWIP effect and the TRIP effect. [3][4][5] The Mn content in these materials is typically one third of the Mn content of the high-Mn TWIP steels, but despite their lower Mn content, these steels achieve excellent mechanical properties with a strength-ductility balance in the range of 35,000 to 45,000 MPa pct.Quenching and partitioning (Q&P) processing was proposed by Speer et al.[6] as a new approach to produce steel microstructures consisting of a low-C martensitic matrix containing a considerable volume fraction of retained austenite. Earlier studies have shown that the Q&P processing of various AHSS enables the use of the TRIP effect to achieve a pronounced improvement of mechanical strength and ductility. [7][8][9] The Q&P processing consists of three stages: an initial quenching stage, a partitioning stage, and a final quenching stage. The austenitized steel is initially quenched to a temperature, T Q , in the M s À M f temperature range, and partially transformed to primary martensite. It is then partition treated at the partitioning temperature, T P . During the partitioning stage, C diffuses from the supersaturated primary martensite into the untransformed austenite. As a result, the M s temperature of the C-enriched austenite is lowered. This leads to the stabilization of the untransformed austenite upon cooling to room temperature. If C does not partition enough to austenite, some of the austenite will transform to secondary martensite in the final quenching stage. The final microstructure consists of C-enriched austenite islands in a low-C lath martensite matrix. The martens...

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“…As a rule, steel billets with a normal ferrite-pearlite structure and strength properties (yield strength up to 600-650 MPa and ultimate strength up to 850 MPa), after hot stamping combined with quenching have a mainly martensitic structure and increased mechanical properties (ultimate strength not less than 1500-1800 MPa). Sheet metal stamping at elevated temperature, due to the martensitic microstructure obtained and reduced elastic aftereffect, may be used to manufacture thin and complex shaped objects with good specific strength and geometric precision [1][2][3][4][5]. Thus, a feature of the phenomenon and transformation during hot stamping consists of a combination of plastic deformation and hardening after steel austenitizing.…”

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confidence: 99%

“…Sheet metal stamping at elevated temperature, due to the martensitic microstructure obtained and reduced elastic aftereffect, may be used to manufacture thin and complex shaped objects with good specific strength and geometric precision [1][2][3][4][5]. Thus, a feature of the phenomenon and transformation during hot stamping consists of a combination of plastic deformation and hardening after steel austenitizing.…”

mentioning

confidence: 99%

Study of Principles for Creating Steel in Order to Prepare High-Strength Reliable Objects by Hot Stamping

2015

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Principles for creating a new generation of steels for preparation of objects by hot stamping with an improvement of strength properties (ultimate strength up to 2200 MPa) by a factor of three are analyzed. It is shown that first of all they should be aimed at simultaneous provision of good steel hot ductility indices, quenchability, and hardenability. It is established that boron-containing steels, and also steels of the alloy and microalloy systems Mn-Cr, Mn-Mo-Nb, Mn-Cr-Ni-(Mo-Nb-V) with an attempt to reduce carbon content are most promising for this purpose. With the aim of verifying the results obtained, experiments are performed for the effect of cooling rate on the steel's strength properties of the alloy systems selected. The adequacy of the main conclusions and the promise of using boron for alloying, and also the system of alloying and microalloying additions C-Mn-Cr-Ni-Nb-V in order to create new low-alloy weldable steels for preparation of objects by hot stamping are confirmed.An improvement in engineering properties of operation, productivity of modern transport, load-carrying, mining, and other forms of engineering unavoidably leads to an increase in load on working assemblies and components. Under conditions of fulfilling a requirement for reducing material and energy expenditure and metal content of objects, this makes it necessary to achieve a breakthrough in increasing strength properties, corrosion resistance, and operating reliability of steels used for their manufacture. An increase in steel strength as a rule leads to a catastrophic reduction in ductility, and this complicates or makes impossible manufacture of complex shapes, particularly those necessary for creating new engineering objects. An effective solution of this problem is development of economically alloyed, weldable, and hardenable during stamping steels providing an increase up to a factor of three is strength properties (ultimate strength up to 2200 MPa) for finished object metal. Use of these steels, apart from a possibility of creating fundamentally new engineering objects for different purposes, will make it possible to reduce cost, metal content, and weight, to improve corrosion resistance, operating reliability and life of objects, particularly under complex natural and climatic conditions, and this becomes even more important in view of implementing wide scale measures for opening up northern latitudes.Practical realization of this approach consists in the following. As a rule, steel billets with a normal ferrite-pearlite structure and strength properties (yield strength up to 600-650 MPa and ultimate strength up to 850 MPa), after hot stamping combined with quenching have a mainly martensitic structure and increased mechanical properties (ultimate strength not less than 1500-1800 MPa). Sheet metal stamping at elevated temperature, due to the martensitic microstructure obtained and reduced elastic aftereffect, may be used to manufacture thin and complex shaped objects with good specific strength and geometric precision [...

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Application of Quenching and Partitioning (Q&P) Processing to Press Hardening Steel

Cited by 81 publications

References 28 publications

Critical Assessment 7: Quenching and partitioning

Critical Assessment 7: Quenching and partitioning

Application of Quenching and Partitioning Processing to Medium Mn Steel

Study of Principles for Creating Steel in Order to Prepare High-Strength Reliable Objects by Hot Stamping

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