제철소 가열로의 배열에너지 회수기술 및 생애주기비용분석 (LCCA & LCA)을 통한 경제성비교 시뮬레이션 연구

임정민 포항공과대학교 철강에너지소재대학원 2021 국내석사

오늘날 온실가스 발생은 국내외적으로 큰 환경 Issue이며 제철소는 많은 온실가스를 배출하는 대표적인 산업체이다. 따라서 온실가스 저감을 위한 배열 에너지회수설비 확대를 위해 본 연구를 통하여 많은 회수 가능한 배열이 발생중인 열간압연공정 가열로 설비의 배열회수 설비기술 조사 및 운영 분석을 하고 배열회수 System 별 환경적 효과와 경제적 효과를 정량적으로 보여주며, 향후 열연 가열로 설비의 배열회수 System 확대적용의 기준을 도출하고자 한다. 본 연구는 다음과 같이 총 네 부분으로 구성된다. 첫 번째 부분에서는 배열회수기술의 비교, 분석하여 최종 기술을 선정하고 실증설비의 System Engineering을 수행하여 System의 Heat&Material Balance를 도출한다. 두번째 부분에서는 실증설비 운영실적 분석결과를 토대로 LCCA (Life Cycle Cost Analysis)를 수행하여 배열회수 System들의 전 생애주기에 대한 LCC(Life Cycle Cost)를 분석한다. 그리고 LCA (Life Cycle Assessment)를 수행하여 전 생애주기에 대한 환경영향평가를 실시하고 비교, 분석을 한다. 이를 통해 각 배열회수 System들의 환경적 효과를 도출하고, 환경적 효과 중 Income, Outcome의 경제적 효과 부분도 산출한다. 세번째 부분에서는 앞선 LCCA와 LCA의 경제적 효과 부분을 포함하여 종합 경제성 분석 및 경제성의 변동성에 대한 Simualtion을 수행한다. 그리고 최종 배열회수 System들의 경제적 효과를 도출하고 경제성을 비교, 분석한다. 네번째 부분에서는 Case별 열연 가열로의 배열회수 System별 적용 기준을 도출한다. 본 연구의 결과를 통해 배열회수 System의 환경적, 경제적 효과가 정량적으로 부각됨으로서 향후 열연 가열로 설비의 배열회수 System이 지속 확대 적용되어 탄소배출 저감에 기여하기를 기대한다. Today, greenhouse gas generation is a large environmental issue at home and abroad, and steel mills are a representative industry that emits greenhouse gases. In order to expand the application of the waste heat recovery system of the furnace in the hot rolling process, this paper aims to investigate waste heat recovery technology and analyze the operation of the waste heat recovery system in the steel mill furnace, quantitatively show the environmental and economic effects of each waste heat recovery system, and derive the criteria for the expansion of the waste heat recovery systems in the future. This thesis consists of a total of four parts as follows. Firstly, the final technology is selected by comparing and analyzing the heat recovery technology, and the system engineering of the actual operating system is performed to derive the Heat & Material Balance of the system. Secondly, based on the operation performance’s analysis results of the actual operating system, Life Cycle Cost Analysis (LCCA) is performed to analyze the entire life cycle of the waste heat recovery systems. In addition, Life Cycle Assessment (LCA) is performed to evaluate, compare, and analyze the environmental impact on the entire life cycle. Through this, the environmental effects of each waste heat recovery system are derived, and the economic effects of income and outcome are also calculated among the environmental effects. Thirdly, comprehensive economic analysis and simulation on economic volatility are performed, including the previous economic effects of LCCA and LCA. These analyses are used to derive the economic effects of the final waste heat recovery systems, as well as compare and analyze economic feasibility. Lastly, the application criteria for each heat combustion heating furnace for each case are derived. As the environmental and economic effects of the waste heat recovery system are quantitatively highlighted through the results of this paper, it is expected that the furnace’s waste heat recovery system of hot mill processes will continue to expand and apply in the future to reduce carbon emissions.

A Study to Correlate between Electrochemical Desulfurization of Molten Iron using CaO-A2O3-MgO Molten Slag and Applied Electric Current

김동현 포항공과대학교 철강에너지소재대학원 2022 국내박사

현대의 철강 산업에서 극청정강 제품에 대한 수요가 꾸준히 증가함과 동시에, 저급 원료 사용량 증대로 용선/용강 (용철) 내 S 등 다량의 불순물을 초래하는 문제를 낳고 있다. 한편, 기존 KR 등의 탈황능은 이미 한계에 다다랐고, 2차 정련에 또한 복황 저감에 대한 기술이 필요한 상황이다. 따라서, 극청정강 제조를 위한 철강 공정 내 새로운 정련 기술 도입이 요구된다. 기존의 용철 탈황 반응의 경우, 생석회(CaO) 기반의 슬래그에 의해 용철 중 S이 환원되어 슬래그 내 CaS 형태로 용해되게 된다. 이를 바탕으로 전기에너지를 이용한 탈황의 전기화학적 반응을 극대화하는 방법이 등장하였고, 많은 선행 연구자들이 전기화학적 탈황의 가능성에 대해 연구해왔다. 대부분의 연구에서 전기 인가에 따른 추가 탈황을 확인하였고, 반응 기구 규명과 속도론적 해석이 중점적으로 이루어졌다. 하지만, 전기화학적 탈황에 미치는 슬래그의 전기적 특성과 실질 전기에너지에 대한 정성/정량적 논의가 부족하였다. 본 연구에서는 일련의 전기화학적 탈황 실험과 열역학적 계산을 통해 CaO-Al2O3-MgO 슬래그에 의한 용철의 탈황능과 인가 전기에너지와의 상관 관계를 확인하고자 하였다. 용강 내 S가 슬래그로 평형 분배될 시점에 특정 전류를 일정하게 인가하여 일반 탈황 대비 전기 탈황 후의 평형 S 분배비 변화를 확인하였고, Nernst 식을 통해 전기화학적 전위차(ΔΦ_S) 추정하였다. 실험 결과, 같은 전류 인가 조건임에도 슬래그 조성에 따라 ΔΦ_S가 변화함을 확인하였다. 다시 말해, 슬래그 내 CaO 함량이 많을수록 전기 탈황 효과가 떨어짐을 의미한다. 이는 슬래그 내 CaO 함량이 많을수록 일반 평형에 유리하다는 정설과는 반대되는 경향으로, 전기화학적 탈황은 슬래그의 전기적 특성에 영향을 받는 것으로 추정된다. 또한, 본 연구에서는 전기화학적 탈황에 쓰이는 저항을 정의하고, 해당 슬래그의 비저항 문헌 보고값과 저항 측정값을 통해, R_DeS (전기화학적 특성)와 R_slag (물리화학적 특성)의 선형 관계를 확인하였다. 전기화학적 탈황 정도를 나타내는 ΔΦ_S는 용융 산화물 내 황화물 용해를 위해 개발된 열역학 모델을 통해 예측할 수 있었다. 전기화학적 탈황은 용철 내 S의 화학적 포텐셜이 감소하는 반면, 슬래그 내 CaS의 화학적 포텐셜은 증가하게 된다. 이를 이용한 열역학 계산 결과, ΔΦ_S는 동일한 전류 인가 조건에서 CaO/Al2O3 함량비가 증가함에 따라 감소하는 것으로 나타났다. ΔΦ_S 예측 모델은 실험 데이터와도 잘 일치하였고, 전기화학적 탈황에 의해 용철의 목표 S 함량 도달에 필요한 전류(또는 전류 밀도)를 추정하는 데 활용할 수 있었다. 본 연구는 또한 전기화학적 탈황의 실조업 적용을 위한 전극재료 및 적용 공정을 제안하고, 예상되는 전기에너지 비용 계산을 시도하였다. 는 용융 산화물 내 황화물 용해를 위해 개발된 열역학 모델을 통해 예측할 수 있었다. 전기화학적 탈황은 용철 내 S의 화학적 포텐셜이 감소하는 반면, 슬래그 내 CaS의 화학적 포텐셜은 증가하게 된다. 이를 이용한 열역학 계산 결과, ΔΦ_S는 동일한 전류 인가 조건에서 CaO/Al2O3 함량비가 증가함에 따라 감소하는 것으로 나타났다. ΔΦ_S 예측 모델은 실험 데이터와도 잘 일치하였고, 전기화학적 탈황에 의해 용철의 목표 S 함량 도달에 필요한 전류(또는 전류 밀도)를 추정하는 데 활용할 수 있었다. 본 연구는 또한 전기화학적 탈황의 실조업 적용을 위한 전극재료 및 적용 공정을 제안하고, 예상되는 전기에너지 비용 계산을 시도하였다. Sulfur (S) should be removed from molten iron during the steelmaking process since the demand for high-quality steel products is growing. Desulfurization of molten iron by molten slag is an electrochemical reaction where S in molten iron dissolves into molten slag as sulfides by gaining electrons. Several previous studies reported the feasibility of electrochemical desulfurization based on its electrochemical character. These investigations confirmed that the application of electricity could decrease the final S content in molten iron below that obtained by normal desulfurization. They primarily focused on the kinetic analysis, reaction mechanism, and electricity efficiency of electrochemical desulfurization. However, the previous studies are lacking regarding the effect of the electric potential on the electrochemical equilibrium and the properties of slag when used for desulfurization. In the present study, the electrochemical desulfurization of molten iron by molten slag was correlated to the electricity applied to the system by conducting a series of electrochemical desulfurization experiments and thermodynamic analyses. A molten iron containing C and S was allowed to react with CaO-Al2O3-MgO_sat. slag at 1400 ºC. It was subsequently desulfurized further by applying electricity of constant current. S distribution coefficients (L_S = (pct S)/[pct S]) were obtained after the normal and the electrochemical equilibria, respectively. The obtained results were interpreted by employing the Nernst equation to extract the electrochemical potential difference (ΔΦ_S) for the electrochemical desulfurization. It was confirmed that applying electric current (I) increased the L_S after the electrochemical desulfurization, which resulted in the increase of ΔΦ_S. A resistance, R_DeS = ΔΦ_S/I, or a specific resistivity, ρ_DeS = ΔΦ_S/(I/A), for the electrochemical desulfurization were defined, which can be used to characterize the susceptibility to the electrochemical desulfurization. The R_DeS was found to be independent of the I within the range of this investigation, to decrease as (pct CaO)/(pct Al2O3) (C/A) increased, and to be proportional to the resistance of the slag (R_slag). On the other hand, the effect of the C content on the ΔΦ_S was negligible when the same slag was used. Favorable conditions for electrochemical desulfurization were not the same as those for normal desulfurization. The ΔΦ_S, which is an indicator of the extent of electrochemical desulfurization, was independently predicted by employing a thermodynamic model for the oxysulfide slag. The enhanced desulfurization by the electricity was interpreted as increasing the chemical potential of S in molten slag (in the form of CaS) relative to that of S in molten iron. It was found that the ΔΦ_S predicted by the thermodynamic calculation decreased with increasing C/A under the same applied current. Moreover, it increased with increasing current at the same C/A ratio. The model prediction was in good agreement with the experimental data. The thermodynamic prediction of ΔΦ_S and the experimental data can be practically used to estimate the electric current or current density (for a set cathodic area) for a desired electrochemical desulfurization. The present study also presented graphite and cermet electrode materials and discussed steelmaking processes for the practical application of electrochemical desulfurization.

Si, Al 함량이 무방향성 전기강판의 자기적 특성에 미치는 영향

최현서 포항공과대학교 철강에너지소재대학원 2021 국내박사

Si 및 Al 함량이 무방향성 전기강판의 자기적 특성에 미치는 영향을 연구하였다. Fe-Si-Al 전기강판에서 {100} 결정립의 자구는 광 자기 커 현미경으로 관찰되었다. 자구의 특성 및 자벽의 이동은 Fe-Al 이원계 합금의 히스테리시스 손실 및 이상 손실과 상관 관계가 있었다. 또한, Si, Al 함량이 무방향성 전기강판의 재결정 집합조직에 미치는 영향을 in-situ heating SEM 을 사용하여 분석하였다. Fe-Al 에서 자구 구조에 주요한 영향을 미친 요인은 자벽 에너지의 감소였다. 따라서, Al 함량이 증가함에 따라 자구 크기가 감소하고 자벽의 영역이 증가하였다. 반면, Fe-Si-Al 에서 Si 함량이 증가함에 따라 정자기 에너지 또한 감소하여, 자벽 에너지의 감소를 상쇄하였다. 이로 인해, Si 함량이 증가함에 따라 자구의 크기가 증가하고 자벽의 영역이 감소하였다. 또한, Fe-Al 에서 히스테리시스 손실, 이상 손실 등과 같은 자기적 특성과 자구와의 상관 관계를 분석하였다. Al 이 6.54 wt.%인 강에서는 90° 자구 벽이 형성되어 자구 구조가 더 복잡하게 변화하였다. 따라서, Al 을 첨가하면 강판의 히스테리시스 손실이 증가하였다. Fe-Al 전기강판의 높은 비저항과 작은 자구 크기에도 불구하고, 이상 손실은 Al 4.68 wt.%까지 감소한 후 포화되었다. 이러한 자기적 특성의 변화는 자화 과정 중에 90° 자벽에 의해 고정되어 발생한 것으로 보인다. 무방향성 전기강판에서 우수한 자기적 특성을 가진 {001}<130> 집합조직은 Fe-2 %Si-1 %Al 에서 가장 잘 발달되었으며, Fe-3 %Si 에서 두 번째로 높은 분율을 나타냈다. Fe-Si-Al 에서 {001}<130> 재결정 집합조직의 발달은 냉간 압연 집합조직과 {001}<130>의 초기 결정립 크기가 주요한 원인인 것으로 분석된다. Influence of Si, Al contents on the magnetic properties of non-oriented electrical steel was investigated. Magnetic domains of {100} grains in Fe-Si-Al electrical steels were observed by magneto optic Kerr microscopy. It is known that the domain size is determined by the energy balance between domain wall energy and magnetostatic energy. As Al contents increased in Fe-Al, domain size decreased because reduced domain wall energy was the dominant factor. As Si contents increased, domain size increased because the reduced magnetostatic energy compensated for the reduction in domain wall energy. The characteristics and motion of magnetic domains are correlated with hysteresis loss and anomalous loss. In electrical steels with Al 6.54 wt%, we observed 90° walls which increases the complexity of domain structures. It was also found that addition of Al caused increase in hysteresis loss. In contrast, anomalous loss decreased until Al 4.68 wt%, then saturated, despite high resistivity and small domain size. These changes of magnetic properties may be caused by pinning of 90° walls during magnetization. Influence of Si, Al contents on the recrystallization texture of non-oriented electrical steel was investigated by in-situ heating SEM. The recrystallization texture was dominated by desirable {001}<130> with weak γ-fiber in Fe-2% Si-1% Al. It was shown that the formation of {001}<130> recrystallization texture could be attributed to the coldrolled texture and the initial grain size of {001}<130>.

Anisotropic yield function calibration strategies for thickness prediction by FE hole expansion test

박홍상 포항공과대학교 철강에너지소재대학원 2021 국내석사

The constitutive model is a crucial tool for the prediction of the behaviors of materials in numerical simulations of sheet metal forming. However, it is a challenge to get accurate results for all the processes because of the limitations of the constitutive model and the specific stress states involved in the process. Therefore, the adaptation of a constitutive model according to the types of process considered is a way to get more reliable results. During sheet metal forming, typical multiaxial stress states are dominant in certain processes such plane strain tension during stretch flanging. The stretch-flange ability of a sheet material is actually well characterized using the hole expansion test (HET) by providing not only the hole expansion ratio but, in addition, the material thickness anisotropy near the periphery of the hole and the localization strain at the end of the process. For the description of plastic anisotropy, a suitable yield condition and different strategies may be developed to determine the corresponding coefficients. In this work, the plane stress anisotropic yield condition Yld2000-2d is employed. The coefficients are usually calculated using a method, called original, that was explained in the original article. In this work, two additional calibration methods are proposed, which consider the dominant stress state during HET, namely, plane strain tension. In the first method, so-called semi-analytical, the coefficients are the solution of a set of equation while in the second, called optimized, the coefficients result from an optimization procedure. To produce input data for this model, uniaxial tension and bulge tests are conducted to produce the standard Yld2000-2d coefficients. For the two new methods, which will be explained in detail in this thesis, additional data are generated from biaxial tension tests with various stress ratios, including for plane strain tension. Hole expansion test simulations are conducted with the different strategies to determine the Yld2000-2d coefficients, i.e. standard, semi-analytical and optimized methods. Thickness true strain profiles along the circumference hole edge and 3 mm away from it are predicted. The simulated and experimental profiles are compared and the best agreement is obtained using the coefficients of the analytical method. However, it is shown that the thickness reduction is not a proper indicator of the fracture location.

Modeling of Predictive Maintenance Systems for Laser-Welders in Continuous Galvanizing Lines (CGL) Based on Machine-Learning with Welder’s Control Data : 데이터 머신러닝 기반의 철강 아연도금라인용 레이저 용접기 고장예지 및 방지 시스템 모델

최진성 포항공과대학교 철강·에너지소재대학원 2023 국내석사

Inclusion Modification of AISI 316L by Addition of AlN via Laser Powder Bed Fusion

이승훈 포항공과대학교 철강에너지소재대학원 2022 국내석사

Metals and alloys manufactured by laser powder bed fusion (L-PBF) are known for having high oxygen and nitrogen concentration compared with those made by conventional casting. L-PBF is characterized by its highest cooling rate among various additive manufacturing (AM) processes. Owing to rapid cooling and high oxygen concentration, oxide inclusions enriched with deoxidizer elements (Si, Mn) are formed in tens of nanometers. These inclusions dispersed in the steel matrix have been recently highlighted to have comparative advantages in properties. Especially, some innovative trials have been successfully carried out to control the size and number density of nano-sized particles by adjusting process conditions. However, those inclusions have some limits being utilized as a strengthening source or a structure modifying agent: MnSiO₃ is amorphous and highly incoherent to the steel matrix, MnCr₂O₄ can easily be agglomerated in liquid metals due to the higher interfacial tension, and MnS could be the origin of pitting corrosion in sulfuric and hydrochloric solutions. Hence, the new oxide inclusions in AM should be suggested and studied. Nitrogen dissolved in steels manufactured by L-PBF has been focused on solutionizing due to its effective solid solution strengthening and benefit of corrosion resistance. However, there is a lack of utilizing nitride particles. Dispersed fine nitrides such as AlN and TiN might also be the strength improving source. The purpose of this thesis is to modify an inclusion by adding aluminum nitride (AlN) into the stainless steel (316L) and investigate its effect on mechanical properties. The preliminary test was carried out to analyze the inclusions formed in maraging stainless steel containing 1.5 wt% aluminum (CX-steel). Aluminum is affirmative with not only oxygen but also nitrogen. So AlN, as well as Al₂O₃ could be formed during the L-PBF process. To research the nitrogen dissolution and nitride formation, the printing was performed with two different shielding gases: Ar and N₂. Under a nitrogen atmosphere, the mass of nitrogen increased slightly. Almost inclusions were alumina in the both samples. Only some nitride particles were found in the nitrogen case specimen. The main experiment was conducted with the mixed powder: 1 wt% Aluminum nitride (AlN) powder and 316L stainless steel powder were mixed to add aluminum (Al) and nitrogen (N) into 316L. The aluminum content of the as-built specimen printed with mixed powder (316L-AlN) was 0.515 wt% while the nitrogen concentration was 0.13 wt%. The most distinguished result of mixing 316L with AlN was the decrease of oxygen concentration from 489ppm to 244ppm. With decreasing the oxygen content, the number density of inclusions was lower than that of normal 316L and the texture of 316L-AlN was different from that of 316L. The alumina inclusions were dispersed in the 316L-AlN matrix. Characteristics of those inclusions were interpreted with scanning electron microscopy (SEM), transmission electron microscopy (TEM). And mechanical properties were measured with a hardness test and a tensile test. The yield strength of 316L-AlN was higher than that of 316L about 80 MPa. Strengthening mechanisms were investigated by considering Orowan strengthening, Hall-Patch equation, and dislocation density.

Development of high effciency & low-cost desulfurization flux for hot metal by utilizing waste red mud

방강호 포항공과대학교 철강-에너지소재대학원 2021 국내석사

고품질 철강 제품에 대한 수요가 증가함에 따라 제품의 황을 낮추기 위한 요소 기술이 요구되고 있고, 고로에서 생산되는 용선 내 황 농도는 저품위 원료, 특히 저품위 코크스의 사용으로 인해 점차 상승 중임. 그럼에도 불구하고 API, 후판제품, 자동차강판 등 황의 농도가 낮은 제품에 대한 수요는 지속적으로 증가하고 있어, 고율적-친환경-저비용의 경쟁력이 있는 탈황 기술의 개발이 필요함. 탈황에는 형석을 함유한 CaO계 Flux가 주로 사용되어 왔지만 유해하기 때문에, 무형석 플럭스의 개발에 대해 많은 연구가 진행되어 옴. 본 연구에서는 알루미나 생산 공정의 부산물인 Red mud를 CaO계 탈황 플럭스와 혼합하여 최적의 탈황 조건을 검토하였음. 탈황 효율(탈황율, 최종 황의 농도)은 Red Mud의 배합비, 환원여부, 기계적 교반 등의 다양항 조건하에서 연구를 진행하였으며, 현재 상업적으로 활용되고 있는 탈황 Flux와의 탈황 효율에 대해서도 비교하였음. 본 연구에서 검토된 Flux는 탈황 효율 면에서 경쟁력 있는 결과를 나타냄을 확인할 수 있었음. 본 연구조건에서는 Red Mud를 환원 후 20% 배합 시 5분 시점의 탈황 속도가 가장 빠르게 나타남. 추가로, 탈황 효율을 정량적으로 평가하기 위해 Index를 검토하였으며, Index는 평형론적 측면에서 최종 탈황 수준을 고려하고, 속도론적 측면에서 10분 시점까지의 속도 상수, 탈황 Flux내 CaO 량을 고려하여 도출하였음. 이렇게 검토된 Index를 기반으로 비교 시에도, 상업적으로 사용중인 Flux 대비 동등 수준의 효율을 확인할 수 있음. 경제적인 측면에서 Red Mud는 부산물로써 원가경쟁력을 가지고 있어, . 탈황 비용을 낮출 수 있을 것으로 예상되며, 실 조업에 적용 가능성에 대해서도 추가적인 검토가 필요할 것으로 판단됨. Demand for high-quality steel products is increasing, and accordingly, refining technology is required to reduce the sulfur content in products. The concentration of sulfur in hot metal produced from the blast furnace increases gradually due to the use of low-grade raw materials. This makes producing low sulfur hot metal after desulfurization difficult. Nevertheless demands for low S products such as API, thick plate products, and automotive steel products keep increasing. Therefore, it is necessary to develop efficient, environmental-friendly, and cost-competitive desulfurization technology. CaO-based flux containing fluorspar has been mainly used for the desulfurization, but it is harmful to human body and environment. Therefore, many studies have been conducted on the development of flux without fluorspar. In the present study, red mud which is a by-product of alumina production process was blended with a CaO-based desulfurization flux to investigate the optimal conditions for the desulfurization. The red med mud was used as a fluxing agent in order to effectively melt the burnt lime. The desulfurization efficiency (removal rate of S and final content of S) was examined by changing conditions, such as mixing ratio of the red mud, pretreatment of the red mud, and mechanical stirring. Desulfurization efficiency obtained in two cases, one with the currently used desulfurization flux in POSCO (Pohang and Gwangyang steelworks) and the other with the desulfurization flux blended with red mud in the present study were compared by a series of experiments on a lab scale. It was found that the flux blended in the present study showed very competitive results in terms of the desulfurization efficiency. A desulfurization index was introduced in order to quantitatively evaluate the desulfurization efficiency: when the pre-reduced red mud was blended with the burnt lime 20% by mass, it showed almost the same level of desulfurization efficiency with the flux used in Gwangyang steelworks, POSCO. In terms of an economical aspect, since the red mud is a by-product or a waste, its use is considered to be free at the moment, thereby giving a cost-competitiveness. It is expected that the cost for desulfurization could be lowered. It has been confirmed in the present study that the same level of desulfurization efficiency was obtained using the red mud mixed flux, when it is compared to the currently used flux in the steelworks. It is expected that this new flux can be used in practical operations in near future.

A Prediction Model for Spot LNG Price Based on Machine Learning Algorithms to Reduce Fluctuation Risks in Purchasing Price

양선필 포항공과대학교 철강에너지소재대학원 2023 국내석사

Study on the formation mechanism of the thermal crack in a low carbon steel

손상현 포항공과대학교 철강에너지소재 대학원 2021 국내석사

티타늄 첨가 보론강의 정적 및 준동적 재결정 거동에 대한 연구

정재훈 포항공과대학교 철강에너지소재대학원 2021 국내석사

The high strength and toughness of wire rode steel are attractive in the automobile industry. Recently, boron (B)-containing steel has been developed to solve profitability and energy saving during the final production. The steel shows better mechanical properties and excellent workability even without complicated heat treatment. Ferrite formation is delayed due to segregated B at grain boundaries, and mechanical properties such as strength, elongation, and toughness increases due to the formation of a multi-phase structure. Ti is inevitably added to secure the BN formation of the alloyed B in the steel. Meanwhile, there was a problem where the bimodal grain structure appeared in the cross-section of the wire rode in the Ti-added B-containing steel. As a result, unexpected failure occurs during final product fabrication due to the inhomogeneity of mechanical properties. This study focused on the factors that determine static and metadynamic recrystallization in Ti-added B-containing steel. Through the single and double hot-compression tests, the empirical equations to describe both recrystallization behaviors were obtained. Higher strain, strain rate, and deformation temperature accelerate recrystallization, while the larger grain size decelerates the recrystallization behavior. Comparing the static and metadynamic recrystallization, metadynamic recrystallization has a larger exponent of strain rate and smaller activation energy. The Avrami index value n is below 1, whereas the conventional low-carbon steels show larger than 1. The grain size of this steel was from 48㎛ to 61㎛ even after reheating to 1,000~1,200 ℃. The formation of TiN affects grain growth and recrystallization behavior by pinning grain boundary motion. The static and metadynamic recrystallization behaviors were determined by comparing the critical strain (strain at the peak stress) and the magnitude of the applied strain. This implies local difference of recrystallization behavior due to the inhomogeneous strain during the steel production process. Therefore, the balance of applied strain is expected to be a critical solution to eliminate the local grain size difference.