The tempering of Fe-C lath martensite

Caron, R. N.; Krauß, G.

doi:10.1007/bf02647041

Cited by 156 publications

(67 citation statements)

References 8 publications

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Section: Discussionmentioning

confidence: 98%

“…The above results of the effect of as-charged hydrogen on uniaxial tensile deformation behavior and fracture is discussed here relative to the literature characterizing the microstructure and substructure of tempered martensite in low carbon steels [23][24][25][26][27][28] and the literature of hydrogen embrittlement in steels. [9][10][11][12][13][14][15][16][17][18] As-quenched martensite in low carbon steels consists of a lath morphology where martensite crystals form parallel to one another in blocks, where the crystals have the same orientation, or in packets where orientations may differ.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Hydrogen Embrittlement of Hardened Low-carbon Sheet Steel

et al. 2010

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Tensile specimens of 10B22 (22MnB5) sheet steels were austenitized, quenched to martensite, and tempered at temperatures between 150 and 520°C for various times. The heat treated specimens were charged with 1.7 ppm hydrogen and immediately tested. Fracture surfaces were examined by field emission scanning electron microscopy. As-quenched martensitic specimens exhibited the most severe embrittlement and failed by stress-controlled cleavage fracture at low stresses. The initiation of hydrogen-induced fracture in specimens tempered between 150 and 350°C was consistent with glide plane decohesion, and coarse inclusion particles served as sources of hydrogen for circular areas of hydrogen-induced cleavage. Specimens tempered at 460 and 520°C showed little sensitivity to hydrogen embrittlement. The progression of decreased sensitivity to hydrogen-induced fracture with increasing tempering temperature correlates with the reduction in dislocations, the principal hydrogen traps, and the formation of cementite particles, considered to be ineffectual traps, with increased tempering. Very small amounts of intergranular fracture were observed, only in as-quenched specimens, confirming that boron has little effect on hydrogen embrittlement of hardened low-carbon steels.KEY WORDS: hydrogen embrittlement; tempered martensite; low-carbon sheet steel; mechanical properties; SEM analysis; fracture mechanism.properties of quench and tempered specimens not exposed to hydrogen. 7,8) The specimens in the current study were tested immediately after hydrogen charging, and recent work by thermal desorption spectrometry on hydrogen trapping capability of quench and tempered low-carbon steels, 17,18) coupled with the results of mechanical testing and fractographic analysis of this investigation, provide useful information contributing to understanding hydrogen embrittlement of the heat treated 10B22 steel. Experimental ProcedureThe chemical composition of the low-carbon steel is given in Table 1. Boron is effectively used in low carbon steels to provide hardenability, and several studies have shown that boron additions in steel have little effect on hydrogen embrittlement. 19,20) Standard ASTM E-8 longitudinal tensile samples were machined from 1.7 mm thick commercially produced cold-rolled sheet steel. The tensile samples were austenitized at 900°C for 10 min in a salt bath and quenched in water. The quenched samples were tempered at temperatures between 150°C and 520°C for times of 600 s, 3 600 s, and 36 000 s in either oil or salt baths and air cooled after tempering.The tensile samples were cathodically charged with hydrogen with a DC power supply in a solution of 1 N H 2 SO 4 with 1 mg/L As 2 O 3 as a hydrogen recombination poison. 21)Charged coupons, 7ϫ7ϫ1.5 mm 3 , were used to determine induced hydrogen content in a LECO RH-404 hydrogen analyzer, and parameters were established to induce a constant hydrogen content of 1.7 ppm in all samples. A current density of 5 mA/cm 2 for 30 min was used for the asquenched samples and 10 mA/cm 2...

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Hydrogen Embrittlement of Hardened Low-carbon Sheet Steel

et al. 2010

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“…As mentioned in the introduction, there are at least four stages of structural changes during tempering of martensite [8,11]. The curves seen in Fig.…”

Section: Dilatometer Studymentioning

confidence: 91%

Effect of Tempering on Microstructure and Mechanical Properties of Laser Welded and Post-Weld Treated AHSS Specimens

Forouzan

Strandqvist

Vuorinen

et al. 2017

MSF

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Abstract. An advanced high strength steel (0.08 %C, 1.79 %Mn, 0.23 %Si) was subjected to different post-weld heat treatments by quenching & tempering treatments (Q&T) after laser welding to reduce the risk of martensite formation in a few seconds based on an idea of quench and partitioning (Q&P), mechanism. The thermal stability of retained austenite, microstructure development and mechanical properties have been studied at 2 tempering temperatures of 440°C (Ms) and 636°C (Bs), both for 15 minutes, by means of electron microscopy, dilatometry, hardness profile and tensile tests. Dilatometer study unveiled that redistribution of carbon atoms and precipitation of transition carbides occur around 150°C and austenite decomposition occur at 600°C. Tempering at 636°C resulted in notable effect on the mechanical properties, while no significant difference was detected at 440°C, except a slight hardness drop. The strength increased up to 12% for the different specimens without significant loss in ductility for all specimens tempered at 636°C, which may be caused by precipitation hardening and recrystallization of martensite lath boundaries during tempering around 600°C.

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“…In addition to suppression of temper softening, the Charpy impact toughness of the DQ3 composition is also maintained at a high level. This is likely a consequence of the fact that the fine lath martensite structure is maintained up to high temperatures in the DQ3 steel, whereas the lath structure disappears in the DQ1 due to absence of (Cr + Mo + V) [12]. This is illustrated in Figure 5c.…”

Section: Temper Annealingmentioning

confidence: 97%

Development of Direct Quenched Hot Rolled Martensitic Strip Steels

Bracke

Knijf

Gerritsen

et al. 2017

Metals

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Metallurgical concepts for new ultra-high strength martensitic steels have been developed through direct quenching after hot rolling. In addition to the chemical composition, the hot rolling, quenching, and annealing parameters need to be optimized to fulfill the requirements for the demanding applications for which these steels are used. It is also shown that the welding behavior is influenced by the choice of alloying concept. Typical applications also require a high fatigue resistance, especially of formed components. For that reason, a dedicated set-up was developed that allows differentiation between materials, which is illustrated through the effect of inclusions on the fatigue performance of a bent test piece.

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The tempering of Fe-C lath martensite

Cited by 156 publications

References 8 publications

Hydrogen Embrittlement of Hardened Low-carbon Sheet Steel

Hydrogen Embrittlement of Hardened Low-carbon Sheet Steel

Effect of Tempering on Microstructure and Mechanical Properties of Laser Welded and Post-Weld Treated AHSS Specimens

Development of Direct Quenched Hot Rolled Martensitic Strip Steels

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