Influence of Initial Pearlite Morphology on the Microstructure Evolution During Heat Treatment of 1.0C–1.5Cr Steel

Bismuth (Bi), as a green free-cutting metal element, has been used for the production of free-cutting steels in the field of free-cutting steel for a couple of decades. One of the merits of bismuth is to improve the machinability of steel, while more Bi addition to steel causes cracking of steels during thermal rolling, attributed to the formation of liquid Bi films. Due to a lack of summary, people have limited mastering the Bi-bearing steels. Herein, the forms and roles of Bi in steel based on the literature survey are summarized. These specific reviews concentrate on the forms, mechanical properties, segregation, solidification, and solubility of Bi in steel, and the effect on grain, machinability, and thermal expansion of steel is also reviewed. This review is of great significance in advancing the understanding of Bi-bearing steels.

Section: Effect Of Bismuth On the Mechanical Properties Of Steelmentioning

confidence: 99%

“…Figure 14. Distribution of grain size in the Bi content 1215MS steels [58,65]. Reproduced with permission [58].…”

mentioning

confidence: 99%

Forms and Roles of Bismuth in Steel: A Review

Xie

2022

“…On the one hand, the effect of pearlite morphology (interlamellar spacing and colony size) on the spheroidization of carbide during annealing is studied. [8][9][10] The smaller the pearlite cluster size and lamellar spacing are, the faster the spheroidization speed is, and the finer, more uniform and denser the spheroidal carbide is. On the other hand, the effects of initial pearlite, bainite, and martensite microstructures on the spheroidizing process are studied.…”

Section: Introductionmentioning

confidence: 99%

Subcritical Spheroidization Annealing of Cold‐Rolled Cr–Mo Microalloyed Medium‐Carbon Steel with Different Initial Microstructure

et al. 2023

According to the industrial production process of fine‐blanking steel (including hot rolling, cold rolling, and spheroidization annealing), a Cr–Mo‐microalloyed medium‐carbon steel is taken as the research object for laboratory simulation in this paper. The ferrite+pearlite (F + P) and ferrite+bainite (F + B) are obtained by changing coiling temperature during hot rolling conduct cold rolling with 25%, 50%, and 75% total reduction and subcritical annealing at 740 °C for 1–8 h. Microstructure evolution during spheroidization annealing is studied and analyzed by an electron probe microanalyzer, electron back‐scattered diffraction, DICTRA simulation, transmission electron microscopy, and microhardness tester. Compared with F + P, the dislocation density distributed to the ferrite of F + B during cold rolling is higher. The cold‐rolled F + B microstructure shows the rapid spheroidization annealing behavior, which leads to the uniform distribution of finer spherical carbides and the full recrystallization of the ferrite matrix. In addition, properly increasing the reduction of cold rolling can also speed up the spheroidization process of carbide. Herein, a 50% reduction is determined to be the most suitable cold‐rolling process parameter for carbide spheroidization. Moreover, the recrystallization of ferrite is enhanced with the increase of cold‐rolling reduction.

“…The report suggested that both the austenite grain size and cementite spheroids could be refined through double‐quenching treatment, which could enhance the final strength and wear resistance. Li et al [ 5,6 ] investigated the microstructure evolution of 52100 steel during hot rolling and heat treatment. They reported that controlled rolling could be combined with conventional quenching treatment, which is also beneficial for refining the grain size and cementite.…”

Section: Introductionmentioning

confidence: 99%

Effect of Preheating on the Microstructure, Impact Properties, and Fracture Mechanisms of a Laser Surface‐Hardened High‐Carbon–Chromium Steel

Yao

et al. 2021

Self Cite

To optimize the toughness and hardness of laser surface‐hardened high‐carbon–chromium (52100) steel, the effect of preheating on microstructure evolution and impact property is studied, and the impact fracture mechanism is analyzed. The results indicate that preheating deepens the hardened depth, facilitating grain coarsening and cementite dissolution near the surface. Regardless of preheating, the size distribution of cementite follows a typical lognormal distribution. Laser surface hardening leads to a decrease in impact absorbed energy. Preheating at 160 °C increases the impact absorbed energy by ≈25%, at which point the maximum hardness is still as high as 860 HV0.3. The impact absorbed energy of spheroidized microstructure tends to be larger before laser hardening and reduces after laser hardening. The impact toughness is the combined result of the brittleness of the hardened layer, residual stress, and substrate microstructure. Under the impact load, microcracks nucleate near the surface of the hardened layer and propagate in the form of intergranular fracture and then propagate in the form of transgranular fracture toward the inside of the hardening layer and substrate. Herein, a novelty research work on optimizing the impact properties during laser hardening through preheating and adjusting initial microstructure is provided.