In this article, the problem of high scrap rate caused by surface defects of a batch of seamless steel pipes for high strength hydraulic cylinders produced on site is analyzed and studied. There are mainly three categories of surface defects, they are rolling skin, pits and pitted surface by analyzing their morphology. The defects are detected and analyzed with such analytical methods as metallographic examination and scanning electron microscope. The results showed that rolling skin and pits were caused by the existing surface cracks of billet before rolling as well as pitted surface was caused due to the roll compacting of surface scale onto pipe body in the process of hot rolling. In order to eliminate the above defects, the corresponding rectification measures are taken as well as the continuous casting and rolling processes are optimized. As a result, the surface quality of products is greatly improved and scrap rate is decreased from 30.6% to 1.7%.

The IS350 rail is medium strength rail in the American AREMA—2019 standard, which is mostly used for laying busy freight railways in North America and with a broad application prospect. Its industrial trial production is carried out combining with the requirements of American standard and the equipment conditions of universal rolling mill of rail. The results of trial production showed that its composition design was reasonable, the smelting, external refining, rolling and online heat treatment processes were proper as well as its general and special performances were in line with the requirements of American AREMA—2019 standard and with sufficient surplus so that a new way was explored for adjusting the product mix of rail of Baotou Steel and developing new markets.

In this paper, the experimental study on heat treatment process of forging area at heel end of 60-50 kg/m U75V hot rolled compromise rail with different finish cooling temperatures and cooling rates is carried out as well as the tensile properties, hardness of top surface of the rail and cross section, microstructure and decarburized layer of forming section, transition section and heat affected zone of the compromise rail are analyzed. The results showed that the finish cooling temperatures of forming and transition sections of the compromise rail were controlled at about 650 ℃, cooling rate was controlled at 1.3~1.7 ℃/s, finish cooling temperature of heat affected zone was controlled below 550 ℃ and cooling rate was not less than 2 ℃/s, with which the problems of high hardness at forming and transition sections, low hardness at heat affected zone and width out of limits at softened zone of the compromise rail could be effectively solved.

In order to meet the demands of heavy haul railways as well as make full use of the functions of chromium and niobium in steel, the high carbon rail for heavy haul railway is researched and developed by adding such strengthening elements as chromium and rare earth into high carbon rail steels through smelting the test steel with laboratory furnace and performance study. The performance indexes of rail are that the tensile strength is not less than 1 330 MPa, elongation is not less than 9%, tread hardness of rail head (HBW) is not less than 390 and other properties could meet the requirements of standard BT/T 2344—2012. The results of trial production showed that the production process of the rail was trouble free and performances could meet the technical requirements, which could satisfy the needs of heavy haul railway.

In this paper, the chemical composition and production process are designed according to the technical requirements of 420 MPa grade high-strength weather-resistant H beam for residential building as well as the performances of test steel are studied by observing the microstructure with metalloscope and transmission electron microscopy (TEM), room temperature mechanical properties and periodic immersion corrosion tests. The results showed that the fluctuation of impact toughness at room temperature for test steel was small and its toughness was good. The yield strength of three test steels with different specifications was higher than 420 MPa and corrosion resistance index (I) was 6.15~6.45, which showed good resistance to atmospheric corrosion. The microstructure of test steels was mainly consisted of ferrite and pearlite as well as the average grain size of ferrite was 25.73 μm and there was nanoscale (Cu, Cr) C precipitated phases in grain.

According to the use requirements of prefabricated steel structure residence, the 420 MPa grade high-strength weather-resistant anti-seismic special hot-rolled H beam with thick gauge is developed independently with the peritectic steel design of microalloy composition system of low carbon, copper and nickel as well as near-net-shape casting technology of beam blank and universal rolling technology of section steel, which is mainly applied for stand column of frame structure for steel structure residence. The subcracks and intermediate cracks inside flange of ingot blank as well as surface defects of finished product caused by rolled-in scale during rolling process are eliminated through optimizing the continuous casting and rolling processes. All the mechanical properties of finished product could satisfy the requirements of technical agreement as well as the dimension and surface quality could satisfy the requirements of standard GB/T 11263—2017 so that its stable bulk supply is realized.

The microstructure and mechanical properties of parent metal for 700L beam steel with different titanium contents and specimens with metal active gas (MAG) welding are compared and studied. The results showed that the ferrite grains in the microstructure of test steel were 3~5 μm, there were a small quantity of deformation bands, yield strength was 678 MPa, tensile strength was 760 MPa and elongation was 17.0% when Ti content was 0.11%; the ferrite grains in the microstructure was 4~8 μm, there were a small quantity of pearlite grains, yield strength was 658 MPa, tensile strength was 734 MPa and elongation was 24.0% when Ti content was 0.07%; the strength of the two types of test steel was increased by about 10 MPa, but elongation was decreased by 1.0 and 3.0 percent points respectively and property of root bending of 180° (d = 2a) was qualified after MAG welding; the content of low carbon martensite was increased and microstructure of heat affected zone for test steel was refined with the increase of Ti content.

The 09CrCuSb acid resistant steel (also known as ND steel) is the low alloy structural steel with resistance to sulfuric acid dew point corrosion as well as is applied in such industrial fields as the metallurgy, chemical engineering and petroleum. In this paper, the mass loss and mass loss rate of 09CrCuSbRE and Q235B are compared with the complete immersion of 24 h, 48 h and 72 h at constant temperature of 70 ℃ as well as take the sulfuric acid with concentration of 50% as corrosive medium. The results showed that the change of corrosion resistance rate curve was not obvious and resistance to sulfuric acid corrosion of 09CrCuSbRE was excellent with the extension of corrosion time. With the extension of corrosion time, the corrosion resistance rate curve of Q235B was risen sharply after 48 h, which indicated poor resistance to sulfuric acid corrosion. There are such elements as Cr and Cu on corrosion surface and in corrosion pit of 09CrCuSbRE through observing the corrosion surface with scanning electron microscope(SEM) and energy spectrum analysis. The elements of Cr and Cu in steel are with the effect of passivating steel surface in corrosion resistant environment to prevent the electrochemical reaction between the corrosive medium and matrix of steel. Moreover, the corrosion rate of 09CrCuSbRE is further reduced by adding such elements as Sb and rare earth(RE) in the steel.

In this paper, the production technology process and technological parameters of spring steel plate 60Si2MnA are introduced as well as the microstructure that products need could be obtained through corresponding cooling technique (4~9 ℃/s) control, which guarantees the mechanical properties of products. The results showed that the spring steel plate 60Si2MnA with tensile strength not less than 1 050 MPa and elongation not less than 13% could be manufactured through choosing appropriate process parameters with the existing equipment and processes under appropriate conditions of liquid iron and other raw materials. Moreover, the thickness of decarburized layer on the surface of high carbon steel 60Si2MnA is controlled better, which is 18% of requirements of national standard GB/T 1222—2016 through controlling the atmosphere of heating furnace.

The maximum concentration of nitrogen oxide emissions in the flue gas of four compressor-turbine units with low heating values using blast furnace and coke oven gas in a steel enterprise is about 250 mg/m³, which could not meet the requirements of limiting values for ultra-low emissions of the steel industry, so the denitration modification is needed. Three different denitration modification schemes are proposed based on studying frequently-used flue gas denitration technologies at home and abroad. The modification scheme of built-in double-layer SCR catalyst in waste heat boiler is finally implemented by comparing such factors as the technology maturity, use risks and operating economy as well as the expected effects are achieved. This study could provide the feasible and effective technical methods for the compressor-turbine unit with low heating values and more nitrogen oxides while without prepared denitration space on site in our country.