• Journal of Korea Foundry Society
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• v.20 no.5
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• pp.336-343
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• 2000

The effects of casting variables and alloying elements on the fluidity of thin wall cast stainless steels were investigated. Melts were poured into the sand molds to produce thin wall test castings. The length of it was 245 mm and the thickness varied at the interval of 0.5 in the range of 1.6 to 2.6 mm. For the same casting condition, the fluidities of austenitic stainless steel, ferritic, precipitation hardenable and martensite ones were better in the order. The higher the pouring temperature, the shorter the pouring rate and the better the fluidity were. The fluidity was increased with the addition of Cr and decreased with W and Nb.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.136-137
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• 2003

Recrystallization textures of ferritic stainless steel sheets of STS 430, the crystallographic texture was modified by means of cross rolling and subsequent annealing. The conventional normal rolling led to the formation of ｛334｝＜483＞ in the final recrystallization texture. Cross rolling in the present work was performed by a 45$^{\circ}$rotation of RD around ND. After recrystallization annealing the cross-rolled samples displayed stronger｛111｝//ND orientations. The cross rolled sample displayed a higher resistance against ridging.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.221-224
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• 2004

The clad samples of five plies of sheets comprising ferritic stainless steel (STS) and aluminum (Al) were prepared by roll-cladding at $350^{\circ}C$. The evolution of strain states and textures during roll-cladding of STS430/AA3003/AA3003/AA3 003/STS430 and STS430/AA3003/STS430/AA3003/STS430 was investigated by measurements of crystallographic textures and by simulations with the finite element method (FEM). Because the deformation mainly occurs in the Al layer during roll-cladding, the present investigation was focused on the Al layers located. The stacking sequence of sheet materials in the clad samples played an important role in the evolution of strain states during roll-cladding.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.225-227
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• 2004

Recrystallization textures of ferritic stainless steel sheets of STS 430 were varied by means of different cold rolling procedures. The conventional normal rolling led to the evolution of strong through-thickness texture gradients in the final recrystallization texture, while the cross-rolling led to a decrease in texture gradients. Micro-texture observation by EBSD revealed that the formation of band-like orientation colonies formed close to the center layer was responsible for ridging. Modification of the recrystallization texture and microstructure by cross-rolling destroyed band-like orientation colonies and consequently reduced the ridging height.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.9
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• pp.770-781
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• 2008

In nuclear power plants, ferritic low alloy steel components were connected with austenitic stainless steel piping system through alloy 82/182 butt weld. There have been incidents recently where cracking has been observed in the dissimilar metal weld. Alloy 82/182 is susceptible to primary water stress corrosion cracking. Weld-induced residual stress is main factor for crack growth. Therefore exact estimation of residual stress is important for reliable operating. This paper presents residual stress computation performed by 6" safety & relief nozzle. Based on 2 dimensional and 3 dimensional finite element analyses, effect of welding variables on residual stress variation is estimated for sensitivity analysis.

• Journal of the Korean Society for Heat Treatment
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• v.23 no.2
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• pp.90-95
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• 2010

The effects of grain size on the corrosion resistance of 429EM ferritic stainless steels for automobile exhaust system were investigated. Using specimens held at maximum service temperature of $950^{\circ}C$ for 10~70 hours, electrochemical polarization tests were conducted. While corrosion current density, $I_{corr}$, was influenced little by grain size, pitting potential, $E_p$, was increased with an increase of grain size. Sensitizaton at grain boundary occurred when the specimen were held at $950^{\circ}C$ for above 50 hours because of the dissolution of precipitates and grain coarsening.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.5
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• pp.680-688
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• 1986

In order to obtain the optimal estimation method of fracture toughness of dual phase steel in which martensitic phase encapsulated islands of ferritic phase, the stretched zone (SZ) method and the R-curve method of the JSME S 001 was discussed. The results obtained are as follows. (1) The $J_{IC}$ values estimated by the SZ method are overestimated as compared with those by the R-curve method. (2) The $J_{IC}$ by the R-curve method decreases with the increase of the ferrite grain size and the martensite hardness. (3) The overestimation of $J_{IC}$ by the SZ method is due to the continuous plastic blunting of ferrite after the formation of stable crack which affects the critical stretched zone width.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.6
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• pp.642-649
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• 2011

The long-term aging of ferritic 2.25CrMo steel was characterized using the acoustic nonlinear effect in order to apply to diagnose the degradation behavior of structural materials. We measured the acoustic nonlinearity parameter for each thermally aged specimen by the higher harmonic-generation technique. The acoustic nonlinearity parameter increased with aging time due to equilibrium M6C carbide precipitation, and has a favorable linear relation with Rockwell hardness. This study suggests that acoustic nonlinearity testing may be applicable to diagnostics on strength degradation in rotor steels.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.11a
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• pp.29-39
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• 1998

It is well known for 410L ferritic stainless steel powder to applicate a sensor ring in anti-lock brake system of automobile, several studies, because of its excellent magnetic properties. This study was carried out In investigate the magnetic properties such as the maximum magnetic induction, coercivity and maximum permeability of the materials with functions of sintering density! time and temperature, and concluded as follows； 1. Sintering under the circumstances of hydrogen gas and tile temperature of $1250^{\circ}C$ for 60min. showed that nitrogen was increased, whereas carbon and oxygen decreased in quantities. 2. Both maximum magnetic induction value of 4700Gauss and permeability of 200 were obtained at the maximum sintering density of 6.89g/$cm^3$. Here, the properties showed a linear increasement with increasing the sintering density. 3. Coercivity sharply increased with incresing the sintering density and reached to 7.6Oe at the maximum sintering density of 6.89g/$cm^3$.

• Journal of the Korean Society for Heat Treatment
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• v.20 no.1
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• pp.22-30
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• 2007

Effects of ferrite grain size on static and dynamic deformation behaviors of SCM415 stels were investigated in this study. Dynamic torsional test was conducted using torsional Kolsky bar with the strain rate of $1.6{\times}10^3/s$. Specimens with three different grain size of ferrite, $4.6{\mu}m$, $11{\mu}m$, $35.5{\mu}m$ were used. Dimple fracture mode of the dynamic test specimens showed adiabatic shear bands on the beneath of fracture surface. Increased uniform elongation and decreased non-uniform elongation appeared as grain size of ferrite decreased in dynamic torsional test. However, shear strength was independent on grain size of ferrite.