Analysis of Precipitation of NbC in Low Reduction Ratio Conditions

Liu, Meiling; Zhu, Guangping; Tang, Heng-Qiang; Ma, Xiaoping; Subramanian, S.V.

doi:10.1007/s13632-021-00749-3

Cited by 3 publications

(1 citation statement)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Chromium is not present in this particle. The formation of such complex particles results from the fact that TiN particles are high-temperature precipitates and fully precipitated before MC-type particles are formed [41]. For these particles present in the matrix, an observable tendency occurs to inhibit cracking.…”

Section: Testing a Fractured Valvementioning

confidence: 99%

Metallographic Evaluation of Increased Susceptibility to Intermediate Embrittlement of Engine Valve Forgings Made of NCF 3015 High Nickel and Chromium Steel

Lachowicz,

Zwierzchowski,

Hawryluk

et al. 2023

Materials

View full text Add to dashboard Cite

This paper focused on determining the increased tendency of cracking after the die forging process of high nickel and chromium steel. The increase in carbon content in austenitic nickel–chromium steel promoted the tendency of valve forgings to forging intergranular crack on the valve head. Attention was paid to issues related to the chemical composition of the material to be considered when hot forming nickel–chromium steel components. Optical and scanning electron microscopies were used to examine the microstructure and fracture features of the samples removed from a fractured valve head. The embrittlement was due to microcavity formation at grain boundaries. Creep theory at grain boundaries was used to explain crack formation. The tensile behavior was interpreted from the evolution of the microstructure during deformation and referred to intermediate brittleness to explain the effect of carbon. It was found that the increased carbon content of the nickel–chromium steel and the strong undercooling observed at the edges of the valve head are factors that promote a reduction in grain boundary cohesion and enhance intermediate temperature embrittlement. Finally, it was found that the formation of a heterogeneous structure manifested by the presence of grain boundary M23C6-type carbides in the austenitic matrix was most likely related to the occurring brittleness.

show abstract

Section: Testing a Fractured Valvementioning

confidence: 99%