Ferrite (iron)

About: Ferrite (iron) is a research topic. Over the lifetime, 20700 publications have been published within this topic receiving 234474 citations.

Effect of Initial Processing on the Microstructure-Property Relationships in Bake-Hardened C-Mn-Si TRIP Steels

Abstract: The effect of pre-straining (PS) and bake-hardening (BH) on the microstructure and mechanical properties has been studied in C-Mn-Si TRansformation Induced Plasticity (TRIP) steels after: (i) thermomechanically processing (TMP) and (ii) intercritical annealing. The steels were characterised before and after PS/BH by transmission electron microscopy (TEM), X-ray diffraction (XRD), and tensile tests. The main microstructural differences were the higher volume fraction of bainite and more stable retained austenite in the TMP steel. This led to a difference in the strain-hardening behavior before and after BH treatment. The higher dislocation density in ferrite and formation of microbands in the TMP steel after PS and the formation of Fe3C carbides between the bainitic ferrite laths during BH for both steels also affected the strain-hardening behavior. However, both steels after PS/BH treatment demonstrated an increase in the yield and tensile strength.

High strength cold rolled steel sheet for automotive use

Abstract: The invention relates to A high strength cold rolled steel sheet having a composition consisting of the following elements (in wt. %): C 0.07 - 0.15 Mn 2.3 - 3.2 Si 0.6 - 1.2 Cr 0.05 - 0.5 Al ≤ 0.2 Nb ≤ 0.1 balance Fe apart from impurities, a multiphase microstructure comprising a matrix of bainitic ferrite and a tensile strength (Rm) of 980 – 1100 MPa

Cold rolled steel flat product and method for its production

Abstract: Cold reduced flat steel product comprises perlite and bainite structure comprising 20-40 vol.% of martensite, 2-15 vol.% of retained austenite and residual ferrite. The flat steel product is made of a steel consisting of 0.12-0.19 wt.% of carbon, 1.5-2.5 wt.% of manganese, 0.60-1 wt.% of silicon, = 0.1 wt. of aluminum, 0.2-0.6 wt.% of chromium, 0.05-0.15 wt.% of titanium, and remaining iron and unavoidable impurities, and has an elongation at rupture (A80) of 15%, a tensile strength of at least 880 MPa, a yield strength of at least 550 MPa, and hole expansion ratio of more than 6%. An independent claim is included for producing the cold-rolled flat steel product comprising Casting a steel melt containing of carbon, manganese, silicon, aluminum, chromium, titanium and remaining iron and unavoidable impurities to form an intermediate in which there is a slab or thin slab, heating the intermediate at an austenitizing temperature of 1100-1300[deg] C, hot rolling the heated intermediate to form a hot strip at a temperature of 850-960[deg] C, cooling the hot strip at a coiling temperature of 500-650[deg] C, rolling the cooled strip using a roller, optionally pickling the hot-rolled strip, cold-rolling the hot-rolled strip into a cold-rolled flat steel product having cold rolling ratio of at least 30%, continuously annealing the cold-rolled steel flat product at a temperature of 750-900[deg] C for 80-300 seconds, and then cooling in two stages, aging the flat steel product at an aging temperature of 100-400[deg] C for 210-710 seconds, cooling the flat product to room temperature, temper-rolling the flat steel product with a roll of 0.2-2%, and optional coating the flat steel product with a metallic protective layer, where the step of cooling the cold-rolled steel flat product includes in the first stage, cooling the product with a cooling rate of 8-100[deg] C/sec to a temperature of 450-550[deg] C and in the second stage, cooling from the intermediate temperature at a cooling rate of 2-100[deg] K/second to a temperature of 350-450[deg] C.

Aging degradation of cast stainless steel

Abstract: A program is being conducted to investigate the significance of in-service embrittlement of cast duplex stainless steels under light-water reactor operating conditions. Microstructures of cast materials subjected to long-term aging either in reactor service or in the laboratory have been characterized by TEM, SANS, and APFIM techniques. Two precipitate phases, i.e., the Cr-rich ..cap alpha..' and Ni- and Si-rich G phase, have been identified in the ferrite matrix of the aged steels. The results indicate that the low-temperature embrittlement is primarily caused by ..cap alpha..' precipitates which form by spinodal decomposition. The relative contribution of G phase to loss of toughness is now known. Microstructural data also indicate that weakening of ferrite/austenite phase boundary by carbide precipitates has a significant effect on the onset and extent of embrittlement of the high-carbon CF-8 and CF-8M grades of stainless steels, particularly after aging at 400 or 450/sup 0/C. Data from Charpy-impact, tensile, and J-R curve tests for several heats of cast stainless steel aged up to 10,000 h at 350, 400, and 450/sup 0/C are presented and correlated with the microstructural results. Thermal aging of the steels results in an increase in tensile strength and a decrease in impact energy, J/sub IC/,more » and tearing modulus. The fracture toughness results show good agreement with the Charpy-impact data. The effects of compositional and metallurgical variables on loss of toughness are discussed.« less