The pipeline steel is mainly used for transportation of oil and natural gas as well as the acid service condition means that there are such acidic mediums as H₂S,CO₂ and H⁺ in application environment, so pipeline steel in acid service condition is the pipeline steel with resistance to hydrogen induced corrosion cracking. In the paper, the development and industrial production of X46MS hot rolled coil are mainly introduced. The development includes chemical components, hot rolling process and production technology process as well as the performance tests include pulling, bending, impact, hardness, metallography, non-metallic inclusions and hydrogen induced cracking (HIC). The test results showed that the chemical components and process design of X46MS hot rolled coil in acid service condition were reasonable as well as it was with pure steel, well-closed formation and excellent mechanical properties, especially the resistance to hydrogen induced cracking.

The microstructure and texture of ingot blank, hot rolled steel plate, cold rolled steel plate and annealed plate are studied with the optical microscope (OM) and X-ray diffractometer (XRD) as well as the magnetic properties are tested with magnetic tester. The results showed that the central equiaxial crystal ratio of continuous casting billet could reach 44.5% with electromagnetic stirring, surface structure of hot rolled steel plate was with perfect recrystallization by adopting high temperature coiling process and average grain size was 28.5 μm as well as the microstructure in the center of hot rolled steel plate was with interlaced composition of recrystallized grain and long strip shape banded microstructure and average grain size of annealed plate was 74.2 μm. The distribution of texture in the thickness direction of hot rolled steel plate is uneven. The surface textures are mainly brass texture and goss texture, textures of 1/4 layer are mainly {100} and {112} components, central textures are mainly {100} and {110} components as well as textures of annealed plate are mainly composed of {111} and weaker {100} planar textures. The magnetic property of sample plate of finished product randomly drawn is measured with the Epstein square method and the results could meet user requirements.

In order to improve the safety management level of company, Baoshan Mining Co. has established and implemented the “235” safety management system that “establish such two systems as workplace safety responsibility system and supervision system of performing duties as the core, strengthen the construction of such three basic systems engineering as safety production standardization, working mechanism of double prevention and safety construction of work team as well as summarize and promote such five types of advanced experiences of safety management as behavior observation, negative list system, five management procedures for breaking rules and regulations, tracing analysis of hidden dangers and accidents and comprehensive evaluation of interested parties”. Baoshan Mining Co. has achieved the goal that there were not any liability accidents of minor injuries or more serious results in 2021 through implementing the new management system.

In this paper, the chemical composition and production process are designed according to the technical requirements of cold rolled 980 MPa martensitic steel as well as the study of its annealing process in laboratory is carried out with pilot-scale test platform. The study results showed that the yield strength was 750~940 MPa, tensile strength reached over 1 020 MPa and elongation was over 10% for the products of cold rolled 980 MPa martensitic steel produced with the same chemical composition and rolling process through adjusting the slow cooling temperature of annealing, which could meet technical requirements. The effect laws of slow cooling temperature on microstructure and properties of cold rolled 980 MPa martensitic steel are clear and definite as well as the soaking temperature is determined to be 800 ℃,slow cooling rate is determined to be 3 ℃/s, rapid cooling rate is determined to be 45 ℃/s and the optimum slow cooling temperature is determined to be 680 ℃ when rapid cooling temperature is 280 ℃ with the composition system combining with the microstructure and mechanical properties of finished products.

The spindle of gang saw, running and positioning of baffle trolley are driven by four Siemens servo motors as well as the control system is 611U frequency converter. The Siemens 611U frequency converter has gone out of production, so the spare parts purchase is difficult and manufacturing cost is high. The spare parts of S120 frequency converter that is widely used in field are universal and it is with easy maintenance. A lot of downtime caused by main drive system failure could be avoided by using the S120 system as backup system of 611U system to synchronize data and switch flexibly so as to avoid affecting productions. After adopt the new S120 system as backup system, the safe operations of production line is ensured, production capacity and maintenance efficiency of equipment are improved as well as the equipment is upgraded and reformed so that the service life and cycle are extended.

The phase transition temperature and static CCT curve at critical point of 800 MPa grade steel for hydropower project with low susceptivity to weld cracking are determined with phase change instrument Formast-F and the dilatation method combing with metallographic method as well as the effects of cooling rate on microstructure are studied. The results showed that the phase transition temperatures of test steel, Ac₁ was 675 ℃, Ac₃ was 875 ℃, Ar₁ was 615 ℃ and Ar₃ was 739 ℃; when the cooling rate was less than 0.25 ℃/s, the transformation products were ferrite (F) + pearlite (P) + a small amount of bainite (B); when the cooling rate was 0.25~1 ℃/s, the transformation products were ferrite (F)+ bainite (B); when the cooling rate was 1~5 ℃/s, the transformation product was bainite (B); when the cooling rate was 5~20 ℃/s, the transformation products were bainite (B)+ martensite (M); when the cooling rate was greater than 20 ℃/s, the transformation product was martensite (M).

The liquid steel could be purified, inclusions could be modified and steel could be microalloyed by adding rare earth into steel, which could reduce the harmful effects of inclusions on steel so that the plasticity, toughness and resistance to low temperature impact of steel could be improved. In order to study the effects of different rare earth contents on properties of steel, the smelting of low alloy high strength steel with manganese and different quantities of rare earth added and without rare earth are carried out using the 25 kg vacuum medium frequency induction furnace as well as the rolling with production process on site is simulated. Moreover, the chemical composition, mechanical properties, fracture and metallographic structure of rolled products are analyzed. The results showed that the grain size of microstructure for steel could be refined by adding rare earth into steel; with the increase of rare earth content in steel, refined grain size of microstructure makes the resistance to crack formation and propagation between grain boundaries increased so that the plasticity, impact toughness and mechanical properties of steel are improved.

In this paper, the effect laws of adding a certain proportion of high silicon Brazilian coarse powder ore into sintering on its technical indicators and quality of sinter with current raw material conditions of Baotou Steel are studied. The experiment showed that the complementary ore proportioning could be realized by adding a certain proportion of high silicon Brazilian coarse powder ore taking the ore proportioning structure that the self-produced iron ore concentrate by Baotou Steel adding Australian limonite and semi limonite as the main framework, which was conducive to improving the quality of sinter. The industrial experiment showed that the rate of sintering finished products, drum strength of sinter and size composition were improved after add the high silicon Brazilian coarse powder ore into sintering of Baotou Steel.

In this paper, the industrial experiments of different heat treatment processes for X65Q seamless steel tube with medium thick wall are carried out as well as its microstructure and properties are tested and analyzed. The test results showed that the martensite content of X65Q seamless steel tube with specification of Ф406.4 mm×26.19 mm was gradually reduced from inner wall to center after quench with 3 300 m³/h inner and outer spraying as well as the microstructure of its internal surface was tempered sorbite+bainite, microstructure of its outer surface was bainite; after quenching, its grain size reached grade 8.5, transverse impact value at 0 ℃ reached over 200 J and yield strength reached over 500 MPa with tempering of 630 ℃ so that the strength and toughness of material matched well, which could meet the requirements of API 5L standard.

The process parameters of hot rolling and controlled rolling, pickling-rolling and continuous annealing for steel strip are determined through the composition system design based on the technical requirements of continuous annealing steel strip HG400 for slide rail. The mechanical properties of the product produced with industrial production line could meet technical requirements and its elongation after fracture is 21%~26%. The study on optimizing the production process of continuous annealing is carried out aiming at the problem that elongation after fracture is lower as well as continuous annealing temperature and elongation of temper mill are adjusted. After the optimization, elongation after fracture of product could be stably controlled at about 31%. At present, the product is produced stably and applied widely.