Temper embrittlement of Ni-Cr steel by Sn

Cianelli, A. K.; Feng, H. C.; Üçışık, A.H.; McMahon, C.J.

doi:10.1007/bf02667390

Cited by 52 publications

(9 citation statements)

References 6 publications

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“…This is a significant observation because Sn is a very potent embrittler of steels. [15] This reveals one strong reason why the high-purity material, with very low levels of impurities, is more resistant to aging embrittlement than the conventional material. These impurity segregation results were supported with limited FEG-STEM results that showed segregation of Ni and Sn, as well as Cu, Mn, As, and Sb, on one boundary in BWS-0, 727 K/50 Kh (Figure 3).…”

Section: A Fatt and Fractographymentioning

confidence: 98%

“…The segregation of impurities to the grain boundaries dramatically compromises the toughness of conventional M152, consistent with the synergistic relationship reported between segregants and hardness on the toughness of Ni-Cr steels. Systematic studies of temper embrittlement have shown a strong synergistic effect of hardness and grain boundary P [11] or Sn [15] segregation in promoting embrittlement. The results from M152 are consistent with this syner- gism.…”

Section: Role Of Major Alloy Elementsmentioning

confidence: 99%

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The long-term aging embrittlement of Fe-12Cr steels below 773 K

Angeliu¹,

Hall²,

Larsen

et al. 2003

Metall Mater Trans A

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When aged for long times at elevated temperatures, Fe-12Cr steels can experience a significant decrease in the fracture toughness, as observed by an increase in the fracture appearance transition temperature (FATT). The mechanism responsible for this decrease in toughness has never been unequivocally explained, but it has been generally attributed to the precipitation of second phases or impurity segregation. The objective of this study was to characterize the microstructural changes in conventional and super clean, electroslag remelted (high-purity) M152 steel aged between 616 K and 783 K up to 50 K hours for correlation to the toughness behavior. Analytical electron microscopy techniques were used to characterize the microstructure and impurity segregation. After aging at 727 K, conventional M152 contained large quantities of alpha prime (Cr-rich, bcc structure) in addition to Cr-rich M 23 C 6 carbides and complex Cr-Fe-Mo-Ni-Si-rich precipitates. High-purity M152 aged at 727 K had a similar microstructure as the conventional material, except for the absence of the Si-rich precipitates. Aging at 616 K revealed the same phases as in the as-tempered material. Aged conventional M152 possessed segregated Sn on the prior austenitic grain boundaries, with equivalent levels of P segregation in both the conventional and high-purity materials. A "deembrittling" treatment of 873 K for 2 hours restored much of the original toughness, correlated with a decrease in hardness and a reduction in the amount of alpha prime phase. These results reveal that the degradation in toughness of M152 upon aging up to ϳ753 K is primarily due to the combination of alpha prime formation and Sn segregation. These results are consistent with temper embrittlement mechanisms, where impurity segregation and second-phase formation synergistically embrittle NiCr steels. Improvements in the longterm aging embrittlement resistance of M152 below 773 K require ultralow levels of embrittling elements, especially Sn, and a reduction in the alloy Cr content to prevent alpha prime formation.

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Section: A Fatt and Fractographymentioning

confidence: 98%

Section: Role Of Major Alloy Elementsmentioning

confidence: 99%

The long-term aging embrittlement of Fe-12Cr steels below 773 K

Angeliu¹,

Hall²,

Larsen

et al. 2003

Metall Mater Trans A

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“…It was assumed that the typical sources of intergranular fracture are the segregation of metalloid impurities to the austenite boundaries (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32) and the formation of a deleterious second phase on the boundaries (39,40,60). The previous conclusion that the intergranular brittleness in Fe-12Mn arises from neither of these causes, but is from its inherent microstructure (14) (Table J) shows a very small amount of P. High resolution SAM studies using high sensitivity nevertheless never show a reasonable amount of P (more than 0.1 atomic percent> on the intergranular fracture surface.…”

Section: Microstructurementioning

confidence: 99%

“…Many high strength steels with small amounts of metalloid impurities have been known to be very susceptible to temper embrittlement (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32) over the temperature range of 550-650°C, or tempered martensite embrittlement 03-38) around 300°C.…”

mentioning

confidence: 99%

Study of intergranular embrittlement in Fe-12Mn alloys

Lee¹

1982

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“…The problem is important, in part because of the deleterious consequences of such segregation on mechanical properties [5][6][7][8]. The enrichment of the impurities at boundaries reduces their cohesive strength, leading in some circumstances to intergranular fracture under load [9][10][11]. Phosphorus is particularly po-tent in this respect [12], causing grain boundary embrittlement when a strong steel is tempered or cooled slowly through a temperature range 600-650 • C [9,13], or the so-called tempered martensite embrittlement at 300-350 • C due to the segregation at cementite-ferrite interfaces [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Segregation of phosphorus to ferrite grain boundaries during transformation in an Fe–P alloy

Kim

Pak

Park

et al. 2014

International Journal of Materials Research

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A binary alloy of iron containing 0.17 wt% of phosphorus has been heattreated under a variety of conditions in order to see whether the segregation of phosphorus to grain boundaries can be controlled. The alloy transforms fully into ferrite. It is found that the majority of solute found at the ferrite grain boundaries has its origins in the temperature range where phase transformation occurs, in other words, phosphorus that is accumulated and dragged with the growing α/γ transformation front. As a consequence, it cannot be suppressed using cooling rates as large as 400 K s −1 .

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Temper embrittlement of Ni-Cr steel by Sn

Cited by 52 publications

References 6 publications

The long-term aging embrittlement of Fe-12Cr steels below 773 K

The long-term aging embrittlement of Fe-12Cr steels below 773 K

Study of intergranular embrittlement in Fe-12Mn alloys

Segregation of phosphorus to ferrite grain boundaries during transformation in an Fe–P alloy

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