The Effect of the Hyperstoichiometric Ti/N Ratio Due to Excessive Ti on the Toughness of N-Controlled Novel Fire- and Seismic-Resistant Steels

Ramachandran, Dileep Chandran; Murugan, Siva Prasad; Moon, Joonoh; Lee, Chang‐Hoon; Park, Yeong-Do

doi:10.1007/s11661-019-05266-1

Cited by 4 publications

(1 citation statement)

References 31 publications

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“…Precipitation strengthening can be achieved by precipitating the nano-scale TiC in ferrite. However, the formation of TiN and TiC at the micron scale can easily result in cleavage fracture, which reduces the low-temperature impact toughness and the fatigue life of microalloy steel [10][11][12][13][14]. In addition, the improper addition of Ti forming micron-scale TiN and TiC also deteriorates the resistance to hydrogen embrittlement [4,15], and causes delayed cracking after flame cutting [16].…”

Section: Introductionmentioning

confidence: 99%

Study of the Fracture Behavior of TiN and TiC Inclusions in NM550 Wear-Resistant Steel during the Tensile Process

Liu

Zhong-yang

Liu

et al. 2022

Metals

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NM550 wear-resistant steel is widely used in large-scale engineering and mining machinery under extremely harsh working conditions. In NM550 steel, the addition of Ti can cause the formation of micron-scale TiN and TiC inclusions, easily triggering cleavage fractures. The fracture behavior and precipitation rule of micron-scale TiN and TiC inclusions on the tensile process in NM550 steel was investigated by scanning electron microscopy, transmission electron microscopy, and energy spectrum analysis combined with thermodynamic theory. The TiN precipitated in the solid–liquid two-phase region at a precipitation temperature of 1710 K, whereas that of TiC was 1158 K along the austenite grain boundary. The sizes of the TiN precipitated in the liquid phase and the TiC precipitated in austenite were both at the micron scale, which is prone to cleavage fracture during the stretching process. Under tensile stress, microcracks were first initiated at the TiN inclusion, which were further separated forming a hole, whereas the TiC inclusion was divided into two sections with a long and narrow gap formed between the substrates. The sizes of the TiN and TiC were related to the cooling rate, Ti, and N contents. The larger the cooling rate and the lesser the Ti and N content, the smaller the TiN and TiC sizes.

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