Influence of Alloying Elements on the Hall-Petch Coefficient in Ferritic Steel

2012 ◽  
Vol 706-709 ◽  
pp. 181-185 ◽  
Author(s):  
Setsuo Takaki
Keyword(s):  
Yield Strength ◽  
Ferritic Steel ◽  
Chromium Content ◽  
Friction Stress ◽  
Ferritic Steels ◽  
Interstitial Free ◽  
Low Carbon ◽  
Petch Relation ◽  
Carbon And Nitrogen ◽  
Solute Carbon

Yield strength of ferritic steel increases with grain refinement standing on the Hall-Petch relation. In low carbon ferritic steels, the following relation is established between yield strength σy and grain size d: σy [MPa]= 100+600/√d [μm]. The Hall-Petch coefficient of interstitial free steels is substantially small as 0.15MPa·√m but it can be greatly increased by the existence of small amount of solute carbon less than 60ppm. As for the effect of substitutional elements such as Cr and P, some papers reports fairly large influence to the Hall-Petch coefficient of ferritic iron. However, the effect of small amount of carbon is sometime neglected or not cleared on the evaluation of Hall-Petch coefficient in ferritic steels. In order to evaluate the effect of substitutional elements, the research should be performed using interstitial free steels to eliminate the influence of solute carbon and nitrogen. In this paper, Hall-Petch relation was examined in iron, Fe-Cr alloys and Fe-P alloys with 0.02-0.05mass% Ti and the following results were obtained: 1) The Hall-Petch coefficient of interstitial free iron is about 0.15MPa·√m. 2) Chromium does not give any influence to the Hall-Petch coefficient of ferritic iron, although the friction stress σ0 is enhanced in proportional to chromium content (Δσ0 [MPa]=7×(mass%Cr)). 3) Phosphorus does not affect the Hall-Petch coefficient of ferritic iron or reduce it somewhat but increases markedly the friction stress σ0 (Δσ0 [MPa]=250×(mass%P)1/2). 4) Even under the co-existence of carbon with chromium and phosphorus, carbon dominantly works to increase the Hall-Petch coefficient of ferritic steels, but it is changeable due to the interaction between carbon and the other substitutional elements.

Review on the Hall-Petch Relation in Ferritic Steel

2010 ◽  
Vol 654-656 ◽  
pp. 11-16 ◽  
Author(s):  
Setsuo Takaki
Keyword(s):  
Grain Size ◽  
Carbon Steel ◽  
Yield Strength ◽  
Yield Point ◽  
Ferritic Steel ◽  
Low Carbon Steel ◽  
Aging Treatment ◽  
Interstitial Free ◽  
Low Carbon ◽  
Petch Relation

Yielding of polycrystalline low carbon steel is characterized by a clear yield point followed by unstable Lüders deformation and such a yielding behavior is taken over to fine grained steel with the grain size of 1μm or less. Yield strength of ferritic steel is increased with grain refinement standing on the Hall-Petch relation. The following equation is realized up to 0.2μm grain size in the relation between yield strength y and grain size d: y [MPa]= 100+600×d[μm]-1/2. In low carbon steel, it might be concluded that the Hall-Petch coefficient (ky) is around 600MPa•μm1/2. However, the ky value of interstitial free steels is substantially small as 130-180MPa•μm1/2 and it can be greatly increased by a small amount of solute carbon less than 20ppm. It was also cleared that the disappearance of yield point by purifying is due to the decrease in the ky value. On the other hand, the ky value is changeable depending on heat treatment conditions such as cooling condition from an elevated temperature and aging treatment at 90°C. These results suggest the contribution of carbon segregation at grain boundary in terms of the change in the ky value. On the contrary, substitutional elements such as Cr and Si do not give large influence to the ky value in comparison with the effect by carbon.

Effect of Carbon and Nitrogen on the Hall-Petch Coefficient of Ferritic Iron (Review on the Hall-Petch Relation in Ferritic Iron)

2010 ◽  
Vol 638-642 ◽  
pp. 168-173 ◽  
Author(s):  
Setsuo Takaki
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Grain Boundary ◽  
Yield Point ◽  
Carbon Steels ◽  
Low Carbon ◽  
Dislocation Emission ◽  
Petch Relation ◽  
Low Carbon Steels ◽  
Solute Carbon

Grain size dependence of yield strength was reviewed for polycrystalline ferritic iron and low carbon steel. Yielding of polycrystalline low carbon steels was characterized by a clear yield point (upper yield point) and such a yielding behavior is taken over to ultra fine grained steel with the grain size below 1m. Yield strength (y) of polycrystalline low carbon steels obeys the Hall-Petch relation: y[MPa]=+600×d[m]-1/2 . The Hall-Petch coefficient ky is around 600 MPa･m1/2 for the commercial low carbon steels but it is lowered to about 100 MPa･m1/2 for interstitial fee steel. Besides, it is known in industrial pure iron (Fe-30ppmC) that ky increases with aging at 363K. The value of ky is also increases with increasing the amount of solute carbon content. The ky is enlarged from 100 MPa･m1/2 to 550 MPa･m1/2 by adding 60ppm of solute carbon and then levels off at around 600 MPa･m1/2 in the carbon concentration region above 60ppm. On the other hand, nitrogen hardly influences the ky value. Difference between C and N in the contribution to ky is probably due to the difference in grain boundary segregation behavior. Macroscopic yielding of polycrystalline ferritic iron is reasonably explained by the Hall-Petch model considering dislocation pile-up against grain boundary and dislocation emission from the grain boundary where stress concentration has been generated by piled up dislocations. It is seemed that the segregated carbon stabilized the dislocation emission site at grain boundary and this leads to the increase in ky.

scholarly journals A Statistical Model of Cleavage Fracture Toughness of Ferritic Steel DIN 22NiMoCr37 at Different Temperatures

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 982 ◽  
Author(s):  
Guian Qian ◽  
Wei-Sheng Lei ◽  
Zhenfeng Tong ◽  
Zhishui Yu
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Statistical Model ◽  
Cleavage Fracture ◽  
Failure Probability ◽  
Ferritic Steel ◽  
Ferritic Steels ◽  
Local Approach ◽  
Weibull Statistics ◽  
Different Temperatures

It is a conventional practice to adopt Weibull statistics with a modulus of 4 for characterizing the statistical distribution of cleavage fracture toughness of ferritic steels, albeit based on a rather weak physical justification. In this study, a statistical model for cleavage fracture toughness of ferritic steels is proposed according to a new local approach model. The model suggests that there exists a unique correlation of the cumulative failure probability, fracture toughness and yield strength. This correlation is validated by the Euro fracture toughness dataset for 1CT specimens at four different temperatures, which deviates from the Weibull statistical model with a modulus of four.

Through Thickness Microstructural Investigation of Temper Rolled Ferritic Steels for Thin Sheet Applications

2010 ◽  
Vol 89-91 ◽  
pp. 73-78
Author(s):  
Caroline Luis ◽  
Monique Gaspérini ◽  
Thierry Chauveau
Keyword(s):  
Thin Sheet ◽  
Sheet Thickness ◽  
Ferritic Steels ◽  
Temper Rolling ◽  
Interstitial Free ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
Shear Tests ◽  
Microstructural Investigation ◽  
X Ray

This paper focuses on the analysis of the microstructure and of the texture through the sheet thickness after temper rolling of very thin ferritic steels. The study uses EBSD and X-Ray diffraction. Comparison is made between an interstitial-free (IF) steel and of some industrial low carbon ferritic steels used after ageing. The experimental results are discussed with respect to the anisotropy of the mechanical behaviour after temper rolling during simple shear tests.

Change in Yield Strength of Nb-Bearing Ultra-Low Carbon Steels by Temper-Rolling

2018 ◽  
Vol 941 ◽  
pp. 230-235
Author(s):  
Ling Ling Yang ◽  
Tatsuya Nakagaito ◽  
Yoshimasa Funakawa ◽  
Katsumi Kojima
Keyword(s):  
Carbon Steel ◽  
Yield Strength ◽  
Low Carbon Steel ◽  
Carbon Steels ◽  
Temper Rolling ◽  
Low Carbon ◽  
Solute Carbon ◽  
Ultra Low Carbon Steel ◽  
Dislocation Strengthening ◽  
Carbon Change

Yield strength of low carbon mild steel decreases when temper-rolling is applied to release yield point elongation. Generally mobile dislocation used to be considered as the cause of the YS lowering. However from Bailey-Hirsch theory, strength should be higher with temper-rolling because of the increase of dislocation density. To newly explain the lowering yield strength by temper-rolling, standing at the point that a few ppm carbon change Hall-Petch coefficient , decrease in yield strength by temper-rolling is investigated using an ultra-low carbon steel. Yield strength of steel with the small amount of solute carbon increased after 2% temper-rolling and didn’t change after aging. On the other hand, yield strength of steel with the high amount of solute carbon decreased after 2% temper-rolling and increased again after aging. Despite solute carbon content, the Hall-Petch σ0 increased by dislocation strengthening of temper-rolling. Hall-Petch coefficient ky of low solute carbon steel remained at the low level even after temper-rolling or aging , however, that of high solute carbon steels significantly decreased after temper-rolling and increased again after aging. Yield strength reduction of the high solute carbon steel can be attributed to the decrease of ky.

MONIT

Alloy Digest ◽  
1982 ◽  
Vol 31 (12) ◽  
Keyword(s):  
Stainless Steels ◽  
Heat Exchangers ◽  
Crevice Corrosion ◽  
Ferritic Steel ◽  
Heat Treating ◽  
Low Carbon ◽  
Good Resistance ◽  
Carbon And Nitrogen ◽  
Temperature Performance ◽  
Corrosive Environments

Abstract MONIT is a titanium-stabilized ferritic steel with extra low carbon and nitrogen. It was developed specifically for demanding corrosive environments. It shows very good resistance to pitting and crevice corrosion in seawater and in this respect it is superior to most other stainless steels. MONIT has good strength, toughness, and weldability; it also tough at sub-zero temperatures after welding. Its uses include scrubbers, condensers and heat exchangers in plants that use seawater or other chloride-containing solutions This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-417. Producer or source: Uddeholm Aktiebolag.

scholarly journals Thermodynamic Calculation of Solute Carbon and Nitrogen in Nb and Ti Added Extra-low Carbon Steels.

1994 ◽  
Vol 34 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Satoshi Akamatsu ◽  
Mitsuhiro Hasebe ◽  
Takehide Senuma ◽  
Yoshikazu Matsumura ◽  
Osamu Kisue
Keyword(s):  
Thermodynamic Calculation ◽  
Carbon Steels ◽  
Low Carbon ◽  
Low Carbon Steels ◽  
Carbon And Nitrogen ◽  
Solute Carbon

Microanalysis of precipitates in a ferritic steel

1978 ◽  
Vol 36 (1) ◽  
pp. 618-619
Author(s):  
J.M. Titchmarsh
Keyword(s):  
Ferritic Steel ◽  
Particle Identification ◽  
Energy Dispersive ◽  
Objective Lens ◽  
Ferritic Steels ◽  
Replica Technique ◽  
X Ray ◽  
Large Numbers ◽  
Scanning Transmission ◽  
Made In

The advances in recent years in the microanalytical capabilities of conventional TEM's fitted with probe forming lenses allow much more detailed investigations to be made of the microstructures of complex alloys, such as ferritic steels, than have been possible previously. In particular, the identification of individual precipitate particles with dimensions of a few tens of nanometers in alloys containing high densities of several chemically and crystallographically different precipitate types is feasible. The aim of the investigation described in this paper was to establish a method which allowed individual particle identification to be made in a few seconds so that large numbers of particles could be examined in a few hours.A Philips EM400 microscope, fitted with the scanning transmission (STEM) objective lens pole-pieces and an EDAX energy dispersive X-ray analyser, was used at 120 kV with a thermal W hairpin filament. The precipitates examined were extracted using a standard C replica technique from specimens of a 2¼Cr-lMo ferritic steel in a quenched and tempered condition.

THE NEW COLD-WORK PEAKS IN LOW CARBON AND INTERSTITIAL-FREE STEELS

1987 ◽  
Vol 48 (C8) ◽  
pp. C8-149-C8-154
Author(s):  
H. B. CHEN ◽  
T. S. CHOU
Keyword(s):  
Cold Work ◽  
Interstitial Free ◽  
Low Carbon
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