본 연구는 지속 가능한 발전과 환경보호를 위한 ESG의 핵심 과제인 탄소중립을 달성하기 위해 최근 철강산업에서 추진 중인 탄소중립 시나리오를 조사하고 그 현실성에 대하여 검토하였다. 2050년까지 탄소중립을 실현하기 위한 시나리오에서 철강산업이 차지하는 비중과 그 계획을 점검하고, 온실가스 감축 단계 및 수소 환원 제철 기술개발 단계에서도 중요한 역할을 하게 될 전기로 제강법의 역할과 과제에 대하여 살펴보았다. 전기로 제강법은 기존의 일반강을 생산하는 단계에서 향후 일관제철소의 전로제강을 대체하는 중요한 역할을 담당해야 한다. 다만 전기로는 전로제강 대비 탄소의 사용은 적으나 전기 에너지가 많이 소비되므로 이에 대한 대응 방안을 마련할 필요가 있다. 이에 논문에서는 전기로의 대체에 따른 전기 에너지의 사용량 증가에 대한 문제점을 도출하고 해결 방안을 제시해 보았다. 향후 철강산업의 탄소중립을 위한 전기로 설비 대체와 전기 에너지의 효율적 사용은 중요한 과제가 될 것이며 사업장 ESG 전략 수립에 필수적인 요소가 될 것으로 기대한다.

Lightweight steel is a crucial material that is being actively studied because of increased carbon emissions, tightening regulations regarding fuel efficiency, and the emergence of UAM, all of which have been recently labeled as global issues. Hence, new strategies concerning the thickness and size reduction of steel are required. In this study, we manufacture lightweight steel of the Fe-Mn-Al-C system, which has been recently studied using the DED process. By using 2.8 wt.% low-Mn lightweight steel, we attempt to solve the challenge of joining steel parts with a large amount of Mn. Among the various process variables, the laser scan power is set at 600 and 800W, and the laser scan speed is fixed at 16.67 mm/s before the experiments. Several pores and cracks are observed under both conditions, and negligibly small pores of approximately 0.5 μm are observed.

한국 철강산업은 어떻게 해서 세계적인 경쟁력을 갖게 되었는가? ‘청암의 탁월한 기업가정신 때문이다‘라고 본 고는 답하고 있다. 기업가정신의 핵심은 혁신이고 혁신적인 경영활동에 의해 기업과 산업의 국제경쟁력이 제고되 기 때문이다. 청암 박태준은 기업가정신을 발휘하여 소명의식을 지닌 임직원을 만들고 경영과 조직을 혁신하여 기업경영 조 건을 향상시키고, 일본정부와 철강산업의 협력을 이끌어내어 요소조건과 관련산업조건을 개선하고, 수출시장을 개척하여 수요조건을 개선하는 등의 혁신을 바탕으로 건설공기와 조업기간 단축 등과 같이 생산성을 향상시킴으 로써 한국 철강산업의 국제경쟁력을 제고시켰다. 즉, 포스코를 창업하고 25년 동안 경영하였던 청암의 기업가정 신으로 인해 한국 철강산업은 세계적인 경쟁력을 확보하게 되었던 것이다. 포스코와 한국 철강산업의 성공요인을 설명하는 기존의 논문과는 다른 차원에서 애국심보다는 기업가정신이 국 가경쟁우위 4개 요인을 개선 및 혁신하였기에 한국 철강산업의 국제경쟁력이 제고되었다는 것이다.

Hydrogen is one of the main candidates in replacing fossil fuels in the forthcoming years. However, hydrogen technologies must deal with safety aspects due to the specific sub�stance properties. This study aims to provide an overview on the loss of mechanical properties of cryogenic materials, which may lead to serious consequences, such as fires and explosions. The hydrogen embrittlement of cryogenic steels was investigated through slow strain rate tensile tests (SSRTs) and thermal desorption analyses of electrochemically H-charged specimens. As a prior study to confirm mechanical properties under liquid hydrogen conditions, the amount of diffusive hydrogen that causes hydrogen embrittlement was confirmed after charging hydrogen using an electrochemical method for 4 types of steel materials applied as cryogenic materials did. When exposed to the same hydrogen charging conditions, the amount of hydrogen diffused into the 9% nickel steel is the highest compared to the austenitic steel type. It is considered that this is because the diffusion and integration of hydrogen into the interior is easy. It is necessary to analyze the relationship between hydrogen loading and mechanical properties, and this will be carried out in a follow-up study.

Due to global warming and environmental pollution, environmental regulations are getting stronger, and the International Maritime Organization announced regulations to reduce CO2 emissions in 2018. In order to respond to this, interest in hydrogen energy is growing, and research on liquid hydrogen is spotlighted for storage and transport of large amounts of hydrogen. Hydrogen reduces in volume to 1/800 when liquefied, but its boiling point is close to absolute zero(-253°C), and hydrogen embrittlement that penetrates other materials and weakens mechanical properties. In this study, the change of mechanical properties under cryogenic conditions (-196 degrees below zero) was confirmed after charging hydrogen into existing cryogenic materials (Stainless steel, High Manganese steel, 9% Nickel steel). In Part I, hydrogen was charged using an electrochemical method and quantitative evaluation was performed. In all four materials, as the changing time increased, the diffusible hydrogen concentration increased. After 24 hours charging, the hydrogen loading of 20 wppm in 9% Ni steel and 15 wppm in high-Mn steel was confirmed. In a follow-up study, we plan to study the effect of hydrogen charging by comparing the results of the mechanical properties test with the above results.

이 논문에서는 다양한 자료를 수집ㆍ활용하여 초창기 한국과학기술연구소 (KIST)가 한국 철강공업에 기여한 바에 대해 분석했다. KIST의 철강공업에 대한 가장 중요 한 기여로는 1969년에 있었던 신사업계획의 수립을 들 수 있다. 신사업계획은 종합제철사업 계획 연구위원회가 마련했으며, KIST의 김재관과 윤여경이 이를 주도했다. 신사업계획은 규 모의 경제, 설비의 구성, 제철소의 확장가능성 등의 측면에서 우수한 내용을 담고 있었다. 신 사업계획을 바탕으로 한국은 일본과의 협상을 추진하여 포항제철소 건설사업을 현실화할 수 있었다. 포항제철의 공식 기록은 오랫동안 신사업계획을 KIST가 주도했다는 점에 대해 언급 하지 않다가 최근에 들어서야 이를 수용하는 모습을 보였다. 이로써 KIST의 연구진이 신사업계획을 주도했다는 점은 KIST의 주장에 머물지 않고 포항제철도 인정하는 사실이 되었다. 신사업계획의 수립 이외에도 KIST는 일본과의 실무협상 추진, 제철소 운영에 대비한 예비조사, 일본 기술자를 활용한 기술자문 등을 통해 포항제철소 건설사업을 적극 지원했다. 이처 럼 KIST의 한국 철강공업에 대한 기여는 계획수립, 실무협상, 기술지원 등을 망라하는 총체적인 성격을 띠고 있었다. 이에 반해 기계공업, 조선공업, 자동차공업 등과 같은 다른 중공업 분야의 경우에는 KIST의 역할이 주로 계획수립의 차원에 머물렀던 것으로 판단된다.

In the current steel structures of high-rise buildings, high heat input welding techniques are used to improve productivity in the construction industry. Under the high heat input welding, however, the microstructures of the weld metal (WM) and heat-affected zone (HAZ) coarsen, resulting in the deterioration of impact toughness. This study focuses mainly on the effects of fine TiN precipitates dispersed in steel plates and B addition in welding materials on grain refinement of the HAZ microstructure under submerged arc welding (SAW) with a high heat input of 200 kJ/cm. The study reveals that, different from that in conventional steel, the γ grain coarsening is notably retarded in the coarse grain HAZ (CGHAZ) of a newly developed steel with TiN precipitates below 70 nm in size even under the high heat input welding, and the refinement of HAZ microstructure is confirmed to have improved impact toughness. Furthermore, energy dispersive spectroscopy (EDS) and secondary-ion mass spectrometry (SIMS) analyses demonstrate that B is was identified at the interface of TiN in CGHAZ. It is likely that B atoms in the WM are diffused to CGHAZ and are segregated at the outer part of undissolved TiN, which contributes partly to a further grain refinement, and consequently, improved mechanical properties are achieved.

Due to the rapid change of global business environment, the growth of China’s steel industry and the inflow of cheap products, domestic steel industry is faced on downward trend. The change of business paradigms from a quantitative growth to a qualitative product is needed in this steel industry. In this environment, it is very important for domestic steel distribution companies to secure their competitiveness by selecting good supply companies through a efficient procurement strategy and effective method. This study tried to find out the success factors of steel distribution industry based on survey research from experts. Weighted values of each factors were found by using AHP (analytic hierarchy process) analysis. The weighted values were applied to DEA(data envelopment analysis) model and eventually the best steel supply company were selected. This paper used 29 domestic steel distribution firms for case example and 5 steps of decision process to select good vendors were suggested.This study used quality, price, delivery and finance as a selection criteria. Using this four criterions, nine variable were suggested. Which were product diversity, base price, discount, payment position, average delivery date, urgency order responsibility and financial condition. These variables were used as a output variable of DEA. Sales and facilities were used as an input variable. Pairwise comparison was conducted using these variables. The weighted value calculated by AHP pairwise comparison were used for DEA analysis. Through the analysis of DEA efficiency process, good DMU (decision making unit) were recommended as a steel supply company. The domestic case example was used to show the effectiveness of this study.

Abstract In this study, Fe-Ni slag, converter slag and dephosphorization slag generated from the steel industry, and fly ash or bottom ash from a power plant, were mixed at an appropriate mixing ratio and melted in a melting furnace in a massproduction process for glass ceramics. Then, glass-ceramic products, having a basalt composition with SiO₂, Al₂O₃, CaO, MgO, and Fe₂O₃ components, were fabricated through casting and heat treatment process. Comparison was made of the samples before and after the modification of the process conditions. Glass-ceramic samples before and after the process modification were similar in chemical composition, but Al₂O₃ and Na₂O contents were slightly higher in the samples before the modification. Before and after the process modification, it was confirmed that the sample had a melting temperature below 1250 ℃, and that pyroxene and diopside are the primary phases of the product. The crystallization temperature in the sample after modification was found to be higher than that in the sample before modification. The activation energy for crystallization was evaluated and found to be 467 kJ/mol for the sample before the process modification, and 337 kJ/mol for the sample after the process modification. The degree of crystallinity was evaluated and found to be 82% before the process change and 87% after the process change. Mechanical properties such as compressive strength and bending strength were evaluated and found to be excellent for the sample after process modification. In conclusion, the samples after the process modification were evaluated and found to have superior characteristics compared to those before the modification.