In this paper, it is comprehensively introduced the energy consumption is reduced by automatically controlling feed pressure based on the drum pressure by frequency converter and stand by pump is ensured to be put into automatic interlocking when the unit is started and in the condition of low load through optimizing control logics under the working condition of “one with two” for frequency converter of high pressure feed pump in the gas-steam combined cycle unit, which lay the foundation for stable operations of the unit.

The hardness of hardened layer for rails after quenching is with hardness gradient and it is difficult to accurately calculate the threshold value ΔK_th of fatigue crack growth for rails. In the paper, the detection of threshold value ΔK_th is carried out through software optimization based on the fatigue crack growth software. The threshold values ΔK_th of U75V and U71Mn quenched rails with different stress ratios are obtained by national standard method and actual measurement method respectively. As a result, the threshold values ΔK_th of quenched rails obtained by actual measurement method are more accurate through comparative analysis of data.

The contents of calcium oxide, silicon dioxide, magnesium oxide, phosphorus and sulfur in metallurgical lime are determined by means of fusion sample preparation-X-ray fluorescent spectrometry. The optimum experimental conditions are determined by analyzing the influences of such factors as fusing agent, release agent, dilution ratio, melting time and temperature on the determination results. Meanwhile, the calibration curves of each element are drawn with standard samples and self-made standard samples with appropriate contents as well as the correlation coefficients are all over 0.999. The experimental samples are determined with test methods. The results showed that the measured and theoretical values of each element could meet the requirements of tolerances as well as relative standard deviations of each element in precision experiment were all less than 5%, which was with higher accuracy and precision. The operation of loss on ignition is not needed for preparing fusion samples in this method so that the experimental processes are greatly simplified and work efficiency is effectively improved, which is with certain promotional and application values.

In this paper, the bending and bullet-proof properties of steel plate BTP500 are tested. The results of 90° folding test for steel plate BTP500 with thicknesses of 6 mm and 9 mm meet the requirements; the tensile strength of steel plate welded with ferritic welding wire is 100 MPa higher than that of the steel plate welded with austenitic welding wire through comparing the results of performance tests for steel plate BTP500 welded with ferritic welding wire and austenitic welding wire. The impact energy of the test plate welded with ferritic welding wire at -40 ℃ is 20~30 J and the weld test of steel plate BTP500 could meet the agreement requirements. With the penetration of bullet, both of the steel plates BTP500 with thicknesses of 6 mm and 9 mm by industrial trial production are not penetrated, which are with very good bullet-proof and anti-penetration properties as well as the bullet-proof property could meet the agreement requirements.

In the paper, the representational capacity of modified Johnson-Cook (m-JC) constitutive model on the high temperature rheological behavior of 304 austenitic stainless steel is studied. The material constants of constitutive model are calculated with the data of experimental true stress-strain for isothermal compression test at different temperatures, strains and strain rates so that the m-JC constitutive model of 304 austenitic stainless steel is established. The applicability of the model is evaluated by comparing the correlation coefficient, average relative error and mean square error of predicted results. The results showed that the average absolute relative error between the predicted results and experimental results of m-JC model was 6.77%, correlation coefficient was 0.987 as well as mean square error was 11.2 MPa so that the m-JC constitutive model could more accurately describe the rheological behavior of 304 austenitic stainless steel.

In this paper, the causes for higher burnup are obtained by analyzing the management and operations of heating furnace in detail based on the heat transfer of billet in heating furnace aiming at the phenomenon that the burnup per ton of steel of regenerative heating furnace in 1^# production line of Long Products Plant of Baotou Steel is obviously higher. A series of improvement measures and operation optimizations such as refining and strengthening the thermal management of heating furnace as well as improving hot charging rate, reducing heat losses, controlling exhaust gas temperature and reasonably controlling furnace pressure are put forward based on the working principles and operating features of regenerative heating furnace so that the gas consumption is effectively reduced, production costs are saved and certain economic benefits are obtained.

At present, the climate change has become the threat and challenge globally. As a large carbon emitter, the iron and steel industry is an important part for achieving the goal of peak carbon dioxide emissions and carbon neutrality in our country. The national carbon emission trading market, as a significant policy tool to reduce greenhouse gas emissions, provides the trading platform for contract fulfillment of carbon quota for enterprises. In the paper, the contract fulfillment scheme of carbon emission quota for iron and steel industry into the carbon emission trading market is analyzed based on the current experiences and methods for power industry participating in the carbon emission trading considering six situations that enterprises could face. Moreover, the suggestions are proposed from such aspects as the low carbon management, precision of carbon emission data and applications of low carbon metallurgical technologies to promote enterprises to transform to be green and low-carbon.

In this article, the different carbon capture technologies, utilization ways and storage technologies of CO₂, demonstration projects and commercial applications of CCUS as well as the challenges facing and development directions are systematically elaborated. Moreover, various carbon capture technologies including the absorption method, adsorption method, membrane separation and other emerging technologies are introduced as well as their feasibility of industrial-scale applications is evaluated by analyzing their principles, advantages and disadvantages; the utilization ways of CO₂ covering such fields as the chemical conversion, fuel production, mineral carbonization and agricultural applications as well as the impacts of different technologies on environmental protection and low carbon economy are discussed. Finally, such technologies as underground storage and ocean storage of CO₂ are elaborated.

The sulfuric acid corrosion resistant steel for railway carriages is with the composition design of low C containing Cr. It is with good comprehensive properties as well as its microstructure is ferrite, bainite and a small quantity of pearlite through the reasonable controlled rolling and controlled cooling process, which could meet the requirements of steel for railway carriages. The scanning electron microscope observation showed that Cu, Cr, Ni and Si were obviously enriched at the interface between oxide layer and matrix of steel. As a result, the adhesive force of oxide layer and matrix is increased to prevent permeation of anions so that the resistance to corrosion of steel surface is enhanced. The corrosion rate of the test steel in the immersion test of 20% sulfuric acid is 6.46 g/(m²·h), which is 20.59% of that of Q355B, so its resistance to sulfuric acid corrosion is excellent.

In the paper, it is elaborated the key trial production plan of 550 MPa grade low alloy high strength steel including the chemical composition, hot rolling, cold rolling and annealing processes in detail as well as studied the effects of alloy elements and production processes on microstructure and properties of products. The trial production results showed that the microstructure of 550 MPa grade low alloy high strength steel was mainly composed of ferrite and dispersed precipitated phase of TiC, its main strengthening mechanisms were fine-grain strengthening and precipitation strengthening as well as its yield strength was 556~581 MPa, tensile strength was 622~653 MPa and elongation was 14.0%~16.5%, which could meet the requirements of relevant standards and product applications.