In the paper, it is introduced the studies on fixed flash welding process of 380HB grade high strength heat treated rare earth rail and normalizing process of joints are carried out with the common fixed flash welder and heat treatment equipment for normalizing of joints at home and abroad. The optimal welding process and heat treatment process of joints are summarized through comparing and analyzing the qualified rate of drop weight tear test, area of grey-spots and Rockwell hardness of longitudinal section for joints with different processes. For the joints of fixed flash welding for obtained 380HB grade high strength heat treated rare earth rail, the mean values of tensile strength R_m, elongation after fracture A and impact energy at room temperature KU₂ are 1 141 MPa, 12.5% and 16.0 J respectively, hardness ratios of joints H_J/H_P is 0.92, H_J1/H_P is 0.84 as well as width of softened zone for joints W≤15 mm so that the mechanical properties and microstructure of joints could all meet the standard requirements. As a result, the problems of lower hardness and drop hammer fracture of flash joint for high strength heat treated rail are solved so that the excellent performance matching of welded joints and rail could be achieved, which could meet the requirements of wear resistance and compliance for heavy-haul railway to joints of high strength heat treated rail.

The purpose of testing water pressure of steel pipe is to confirm whether there is any water leakage with authorised pressure so as to ensure its performances to meet user requirements. In order to manage the test data for water pressure of steel pipes more effectively and improve flexibility of reports, the test data sheet for water pressure of steel pipes is established with Access database. The archiving and extraction of test data for water pressure of steel pipes are realized by using codes of WinCC VBScript and adopting mode of instruction programming so that the analytical capability for water pressure of steel pipes is improved. As a result, the archiving management of data is more user-friendly, which wins user’s recognition.

In order to relieve the environmental pressure caused by a large amount of waste in the process of smelting rare earth, the experimental study on beneficiation of high grade rare earth ore concentrate of Bayan Obo is carried out. The sodium silicate is as inhibitor, reagent of hydroximic acid is as collecting agent and 2^# oil is as foaming agent as well as the closed circuit experiment process of “one time of rougher flotation and four times of concentrations” is adopted in the flotation test of rare earth. As a result, the rare earth ore concentrate with grade of 62.79% and recovery rate of 84.73% is obtained, which lays a good foundation of raw material for subsequent clean productions.

The rail head of 43 kg/m rail with material of U71Mn after induction hardening by user is cracked during straightening process. The rail is inspected with such methods as the chemical analysis, fractography, metallography detection and scanning electron microscope analysis. The results showed that the chemical composition could meet standard requirements, fracture morphology of fracture origin and microstructure were abnormal, melting holes and oxidation characteristics at grain boundary could be seen locally. The offline quenching induction heating process is judged to be abnormal. Different degrees of overburning and overheating are formed in near surface area at round corner on one side of rail, i.e. oxidation and melting at grain boundary. The abnormal microstructure of coarse cementite+ledeburite is formed after quenching so that the rail is cracked in subsequent straightening process.

In this paper, the development process of SS105 grade rare earth microalloying seamless tube for drill pipe body resistant to H₂S stress corrosion is introduced. The designs of its chemical composition system and key production process are carried out according to the requirements of technical specification of a company and the API Spec 5DP 2020 Drill Pipe Specification as well as trial production of the product is carried out at the same time. The quality of continuous casting billet as well as chemical compositions, mechanical performances, metallographic structure and non-metallic inclusions of finished product are tested, all the indexes could meet design requirements. The effects of rare earth Ce on resistance to H₂S stress corrosion of SS105 grade seamless tube for drill pipe body are evaluated based on its service environment of the oil and gas drilling environment with high content of H₂S and low temperature. The results showed that the resistance to H₂S stress corrosion of the product was significantly improved after add rare earth into it.

On the occasion of the 70th anniversary of establishment of Baotou Steel, the works done for transformation and upgrading of key technologies and equipment of rail of Baotou Steel, creating characteristic rail products with advantages of rare earth resources as well as developing new technologies and steel grades of rail to satisfy the demands of rail market at home and abroad are summarized in this paper. In the 70-year process of enterprise development, brand building of rail of Baotou Steel becomes mature continuously with the enterprise development. Relying on advantages of rare earth resources and technological inheritance, Baotou Steel strives to create characteristic brand of rail to support the brand development strategy of “rare earth rail” and puts forth effort to building rail products as well known brands at home and abroad. Moreover, the brand advantages are transformed into driving forces of enterprise development, various property indexes of rail products are continuously improved by closely combining with the demands of user side so that rail of Baotou Steel could always maintain advanced level in the industry.

The warping on surface of hot rolled plate and strip is always the common defect that troubles production of high quality strip. The causes for warping defect on surface of steel could be throughout the whole process of steel production such as smelting, continuous casting, hot rolling and cold rolling. The types of warping defect are various and influencing factors are complex. The causes of common warping defect are classified into 5 types based on their morphology and microstructure characteristics, which are subsurface inclusions, surface cracks, subsurface bubbles, rolled-in scale and edgefold of intermediate billet. The probability of occurrence of warping defect for products could be reduced significantly by enhancing management of production equipment and process interfaces, especially increasing the level of continuous casting process from the origin to improve surface quality of ingot blank.

As the important steel of basic building components, screw-thread steel is widely used in such engineering constructions as buildings, bridges and roads. Its proportion of carbon emission is higher in building materials due to its large consumption so that the management and evaluation research of carbon footprint in its manufacturing process are particularly important. In this article, the key direction for its carbon reduction is found out through analyzing operation and conversion of carbon flow in its production process. The data of carbon emission and carbon footprint of products is qua.pngied as well as all of potential influencing factors are calculated with the LCA method so as to ide.pngy and control key areas of carbon emission, which could provide guidance for Baotou Steel to establish measures and plans of carbon reduction as well as environmental product declarations(EPD) of screw-thread steel products are successfully released on the EPD platform.

With the increasing demand of high quality carburizing steel for key spare parts as well as proposal of “carbon peaking and carbon neutrality goals”, the requirements for such comprehensive properties of carburizing gear steel as wear resistance and strength and toughness are higher. It is the development direction of carburizing gear steel to develop high efficiency, energy saving, low carbon and economic high temperature carburizing technology with rare earth microalloying. In the paper, it is discussed the key problems and regulation of microstructure and properties for applications of rare earth in high temperature carburizing gear steel as well as summarized the applications and development trend of high temperature carburizing for gear steel with rare earth microalloying through introducing the applications and development situations of high temperature carburizing gear steel at home and abroad, which are of great significances for developing high temperature carburizing gear steel with rare earth characteristics.

In the process of developing high quality steel, rare earth elements are widely used and effects are significant. In this paper, the mechanisms of action and lack of research of rare earth elements in steel are summarized as well as application situations of rare earth elements in wear-resistant steel, H beam and corrosion-resistant steel are overviewed. The design thinking of determining additive amount of rare earth by scie.pngically applying the first principle of density functional theory and combining mismatch theory with thermodynamic calculations is proposed aiming at such problems as lack of researches for the theory of determining additive amount of rare earth as well as solid solution of rare earth and mechanisms of action of the rare earth at grain boundary in steel, which could provide the thinking and references for design and wide applications of rare earth steel alloy.