In the paper, the study on effect laws of ore proportioning structure on quality of pellet is carried out aiming at such problems as low strength and high reduction swelling rate of manufactured pellet caused by high contents of such harmful elements as K, Na, F and S in iron ore concentrate of Bayan Obo. The study results showed that the pellet could be promoted to be fully oxidized, compressive strength of pellet could be improved and reduction swelling of pellet could be restrained by adding high silicon hematite and high magnesium magnetite with low contents of sulfur and alkali metal. The compressive strength of pellet could be significantly increased to 2 380 N and reduction swelling rate could be reduced to 13.2% with the scheme of optimizing ore proportioning that 52% iron ore concentrate of Bayan Obo+32% high silicon and low sulfur magnetite concentrate+8% high silicon hematite concentrate+8% high silicon high magnesium magnetite concentrate, which could provide the theoretical support and technical path for preparing high quality pellet with iron ore concentrate of Bayan Obo.

In order to effectively break through the bottleneck problem of capacity of sinter, upgrading and transformation of existing 265 m² sintering machine are implemented. The capacity of sintering machine is significantly enhanced through adopting a series of measures including widening trolley, upgrading main exhauster and optimizing pelletizing system. After the transformation, average daily output of sinter is increased by 1 013 t and utilization coefficient of sintering machine is improved from 1.332 t/ (m²·h) to 1.484 t/ (m²·h); drum index of sinter is increased by 0.3 percentage point and its size composition is improved; solid fuel consumption of sintering is decreased by 1.19 kg/t and electricity consumption is decreased by 4.97 kWh/t so that the energy medium and manufacturing costs are significantly reduced.

In the design of blast furnaces in Baotou Steel, “long campaign of blast furnace” is always the subject. In order to adapt to the smelting of special ore in Bayan Obo, blast furnace profile is gradually developed towards low shaft, the part below middle of blast furnace shaft is constructed with microporous alumina carbon brick instead of carbon brick, thick furnace lining is gradually changed to thin skinned lining, furnace hearth is with domestic large carbon brick and high heat-conducting UCAR carbon brick as well as low heat-conducting furnace hearth is changed to high heat-conducting furnace hearth. The production technology management system that could ensure stable and smooth operations of blast furnace, high output and low consumption as well as campaign of blast furnace to be over 15 years is formulated through paying attention to construction quality, optimizing cooling equipment and medium parameters, adhering to the principle of beneficiated burden material, controlling contents of harmful elements as fired, keeping furnace hearth active as well as strengthening technologies and management measures at later stage of campaign.

The alloying before VD (vacuum degassing) process is developed by optimizing slag formation process and deoxidation system of LF (ladle furnace) as well as the alloying operation after VD is changed to before VD process aiming at such problems as fluctuation of composition of molten steel, excessive inclusions and long production time caused by lagged alloying operation after VD in the vacuum treatment process of aluminium killed steel. The application practices showed that the holding time of white slag was extended to 15~20 min, total oxygen content of molten steel after VD was reduced to 0.001 2%~0.002 0%, rating of fine B class inclusion (Al₂O₃) was decreased from grade 2.0 to grade 1.0 and power consumption of refining was reduced to 48.51 kWh/t.

The structural steel is widely used in such industries as automobile, construction and photovoltaics due to its good comprehensive properties. In this paper, the effects of different microalloyed compositions and metallurgical process routes on microstructure and properties of 350 MPa grade products are studied and determined based on the differences of CSP (compact strip production) and conventional hot continuous rolling aiming at the request for utilization of photovoltaic products while considering effective productions of production line. The study results indicated that the properties of products manufactured with different process routes could all meet standard requirements. Although the contents of strengthening elements (carbon, manganese and titanium) in products with CSP production line are lower than those in products with conventional hot continuous rolling production line, the yield strengths of products manufactured with the two production lines are approximate, which are 400~460 MPa.

In this paper, the microstructure, microtexture and macrotexture of DC04 deep drawing automobile steel in different process states are studied, transverse and longitudinal yield strength, tensile property, percentage elongation after fracture, n value and r value as well as which in direction of 45° of the test steel with thickness of 0.6~2.0 mm are with statistical analysis. The results indicated that the fluctuation of transverse and longitudinal tensile property, n value and r value and which in direction of 45° of the test steel with thickness of 0.6~1.0 mm was great as well as proportion of cracked parts was 79.7%; the stability of such properties as transverse and longitudinal tensile property, n value and r value and which in direction of 45° of the test steel with thickness of 1.2~2.0 mm was improved as well as proportion of cracked parts was 20.3%. The microstructure of as-hot-rolled test steel is mainly equiaxed crystal ferrite, surface layer is with deformation textures {001}<110>, {112}<110> and {554}<225>, subsurface layer is with deformation texture {111}<112> as well as the core is mainly with rotating cubic texture {001}<110>; the microstructure of acid-rolled test steel is mainly fibrous ferrite, main textures are α texture {112}<110>, γ texture {111}<110> and λ texture {001}<110>; the microstructure of annealed test steel and finished product is mainly recrystallized ferrite, annealed test steel is composed of stronger γ texture ({111}<112> and {111}<110>) and α texture, finished product is mainly composed of γ texture {111}<112>. The macrotexture of test steel with good formability is γ texture ({111}<110> and {111}<112>) as well as intensity is around 10; the macrotexture of test steel with poorer formability is mainly {100}<011> and {112}<110>, intensities are 9.00 and 8.54 respectively as well as proportion of macrotexture {111}<110> favorable to deep drawing is smaller.

As a kind of revolutionary steel material, Zn-Al-Mg coated steel is gradually becoming the ideal substitute of traditional galvanized steel sheet and Al-Zn alloy coated steel sheet due to its excellent corrosion resistance and edge trimming protection effect as well as good formability and surface appearance. In this paper, it is reviewed the chemical composition system, effects of various elements, current status of research and development at home and abroad as well as patents and researches on application technologies for Zn-Al-Mg coated steel. Moreover, it is mainly sorted out and compared the composition design, microstructure characteristics and performance features of Zn-Al-Mg coated products of different systems in Japan, Europe and China. Finally, the future development trend of Zn-Al-Mg coated steel is expected to provide references for further research and development and applications of this material.

The Zn-Al-Mg coated steel sheet is widely used in such industrial fields as automobile and construction due to its excellent corrosion resistance. Its stamping performance, the key factor affecting product quality and production efficiency, is always research hotspot in the industry. In the paper, it is summarized the research status of stamping performance for Zn-Al-Mg coated steel sheet including its research background, development sequence, influencing factors, research methods as well as problems and challenges faced. Early researches are the preliminary exploration of stamping performance and researches are gradually deepened with technological progress, which include such aspects as composition, microstructure, thickness of coating and mechanical properties of steel sheet as well as experimental testing and numerical simulation technique become the main research methods. At present, there have been many break through points in the research of stamping performance for Zn-Al-Mg coated steel sheet, but challenges are still faced in terms of performance balance and evaluation of complex working conditions. In the future, the applications of new technologies and deepening of multifactor coupling research are expected to promote further development of this product.

In the article, it is mainly introduced the hot-dip galvanized green steel product BTRC20 for home appliances is successfully developed by adding over 20% scrap steel as well as utilizing existing process equipment of smelting, hot rolling, cold rolling and galvanizing of Baotou Steel. Its yield strength is 212~279 MPa, tensile strength is 331~368 MPa and elongation is 31.0%~50.5%. Various indexes of developed hot-dip galvanized steel sheet BTRC20 for high-end home appliances such as mechanical properties, corrosion resistance and coating performance could all meet the technical standard of delivery. It is widely used for manufacturing the out board of such high-end home appliances and office equipment as computer, server, audio equipment and automatic office system, which is with stable bulk supply capacity.

In this paper, the surface corrosion resistance of non-passivated galvanized steel strip DX51D+Z is studied with 24 h neutral salt spray test as well as the influences of such factors as amount of greasing on surface, standing time and surface treatment methods on formation of white rust on surface are investigated. The study results showed that the amount of greasing on surface and standing time after greasing were the main factors influencing corrosion resistance of non-passivated galvanized steel strip DX51D+Z. The corrosion resistance of non-passivated galvanized steel strip DX51D+Z could be effectively improved by optimizing such surface treatment processes as combining greasing in production line with manual greasing and controlling standing time after greasing within 96 h, which could meet the acceptance target of area of white rust on surface ≤5% after 24 h neutral salt spray test.