In the detection of building foundation piles, crosshole sonic logging is the important detection method to judge the integrality of pile body for cast-in-place concrete pile. In this paper, it is introduced the basic principle and judgment basis of detecting integrality of pile body with crosshole sonic logging as well as summarized the process flow and matters needing attention of on-site detection by taking the project of archives center in a city as an example, which provide accurate detection data for the quality of foundation pile in project.

In China, the steel for steel structure is mainly plate and applications of hot rolled H beam (RH) in steel structure is growing slowly. The use level of RH accounts for only 15% of total amount of H beam, which is relatively lower and the rest is welded H beam (BH). In this article, the specifications, types, production processes, residual stresses, microstructure at R corner, advantages and disadvantages as well as future development trends of BH and RH are compared and analyzed. Moreover, several countermeasures for the application bottleneck of RH in construction steel structure are proposed.

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 the paper, it is proposed how to select the pipeline material and some matters needing attention in low temperature environment condition by analyzing the lowest design operating temperature of gas pressure piping in the iron and steel industry. The gas pipe in the iron and steel industry is usually with large pipe diameter and low pressure, so it is not pressure piping. With the development of new technologies, some gas pipes with pressure higher than 0.1 MPa are pressure piping. The design of material should be based on the pressure piping code. In the severe cold area, when the lowest design operating temperature of pipe is lower than -20 ℃, the applicability of materials selected for pressure piping in low temperature conditions shall be considered.

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.

Tower crane is the mechanical equipment playing a leading role in the construction of high rise buildings as well as it is widely used because it could achieve any work height and work range through installing and attaching. Its installation and disassembly are more dangerous projects, so construction organizations should pay high attention to the safety technology management of installing and disassembling tower crane. In the paper, it is introduced the construction process of demolition with tower crane, mainly discussed the problems need to be solved in the process as well as elaborated the construction preparation, order of demolition with tower crane, safety precautions and reinforcement measures of truck crane at different positions of roof for underground garage in detail, which could be as the reference for construction of demolition with tower crane.

With the increasing development and utilization of marine resources, corrosion of structural materials of marine engineering is facing severe challenges. In this article, it is summarized the research progress on corrosion status of steel in marine environment as well as deeply analyzed such influencing mechanisms as marine atmosphere, splash zone of seawater, tidal and splash zone as well as immersion zone of seawater on corrosion behavior of steel. The main current technical measures to retard corrosion of steel in marine environment are summarized as well as development direction and application prospect in future marine engineering of new corrosion-resistant steel are discussed by discussing the effects of such environmental factors as dissolved oxygen, salinity, temperature, pH value and microorganism on corrosion rate of steel aiming to provide the technical support for improving corrosion resistance of structural materials of marine engineering.

In the paper, the technical progress of ironmaking system of Baotou Steel is summarized and analyzed. It is thought that the technological breakthrough and innovation of beneficiation, sintering and smelting problems for special iron ore of Bayan Obo are fundamental guarantee for achieving the ironmaking production with high efficiency and quality, low consumption, long service life and environmental protection as well as technical support of great-leap-forward development for ironmaking of Baotou Steel.

In the paper, it is elaborated comprehensively integrate idea of green development in procurement activities, drive green development of procurement by means of digital intelligence tools, promote green manufacturing with green procurement, build brand of green digital intelligence supply chain, guide and drive green, low carbon and circular synergetic development of upstream and downstream enterprises as well as accelerate green and low carbon transformation development of the entire chain for iron and steel enterprises from the perspective of modern supply chain, which could play a role of demonstration and leading for state-owned enterprises to achieve the national strategic goal of “carbon peaking and carbon neutrality” as well as provide strong supports for accelerating establishment of world-class enterprise.

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.