Pearlite

About: Pearlite is a research topic. Over the lifetime, 6028 publications have been published within this topic receiving 65695 citations.

The mechanical properties and corrosion behaviors of ultra-low carbon microalloying steel

Abstract: The continuous cooling transformation (CCT) microstructure evolution in low carbon Mo–Nb–Cu–B microalloying steel (LCS) was investigated by thermo-simulation test. It was found that the full multi-phase of intermediate transformation products could be obtained at cooling rate greater than approximately 2 °C/s. In order to get bainitic microstructures, the thermo-mechanical control process (TMCP) was worked out according to CCT microstructure characteristics. After TMCP, 750 MPa grade steel twice over that of weathering steel 09CuPCrNi (WS) with ferrite and pearlite structures could be achieved. The corrosion behaviors of LCS and WS were also studied by wet-dry cycle corrosion test. The results showed that LCS had higher corrosion resistance than WS, attributed to suppression of the formation of pearlite.

Machinable austempered cast iron article having improved machinability, fatigue performance, and resistance to environmental cracking and a method of making the same

Abstract: A machinable austempered cast iron article has improved strength, machinability, fatigue performance, and resistance to environmental cracking. A method of making the machinable austempered cast iron article includes austenitizing an iron composition having a substantially pearlitic microstructure in an intercritical temperature range of between 1380° F. and 1500° F. This produces a ferritic plus austenitic microstructure. The ferritic plus austenitic microstructure is quenched into an austempering temperature range of between 575° F. and 750° F. within 3 minutes to prevent formation of pearlite. The ferritic plus austenitic microstructure is then austempered in the austempering temperature range of between 575° F. and 750° F. to produce a microstructure of a continuous matrix of equiaxed ferrite with islands of austenite. Finally, the microstructure of the continuous matrix of equiaxed ferrite with islands of austenite is cooled to ambient temperature to produce the machinable austempered cast iron article.

Additivity hypothesis and effects of stress on phase transformations in steel

Abstract: Theoretical analysis shows that the fraction of pearlite formed from nucleation is additive and that from growth is not. A modified additivity model is established with two continuous cooling experiments. Calculations of Ae 3 temperature for proeutectoid ferrite formation under stress and nucleation rate as well as incubation period of ferrite or pearlite transformation under stress are successfully made. Kinetics equations for ferrite and pearlite transformations under stress are expressed from modification of J–M–A equation with addition of a stress item. The acceleration effect of stress on bainite formation is mainly attributed to the increase of diffusivity of solute atoms and even iron. By consideration of the grain size effect, Patel and Cohen’s equation expressing the effect of stress on M s is modified. Calculations of M s for fcc → bcc(bct) and fcc → hcp under stress are introduced. An equation showing the relationship between strain and nucleation of martensite which can well explain the morphology of martensite formed under stress is mentioned. Appearance and mechanism of mechanical stabilization of austenite in martensitic transformation, i.e., the lowering of M s , resulted from the work hardening of austenite, are different from retardation of bainite formation under stress, i.e., after B s raising, occurring the retardation of bainite growth resulted from hindrance by defects.

Micromechanism of cleavage fracture in fully pearlitic steels

Abstract: The micromechanism of cleavage fracture in a fully pearlitic steel has been investigated Uniaxial tensile and compression test specimens, together with single notched bend (SNB) and double notched bend (DNB) specimens, were heat treated such that the prior austenite grain size remained constant while the pearlite interlamellar spacing was varied The SNB specimens were used to determine the cleavage fracture stress σfM, over the temperature range −25 to −196°C The DNB specimens were used to study the initial stages of crack nucleation The results indicate that pearlite can exhibit two different cleavage mechanisms which are dependent on the strength of the steel For cleavage fracture stresses below about 2100 MN m−2, fracture is nucleation controlled and involves shear linking of carbide nucleated microcracks before unstable cleavage can occur Under these conditions, the cleavage fracture stress is dependent on temperature and is proportional to the uniaxial proof stress For cleavage fractur