As the calibration item of Rockwell hardness tester, hardness of ball indenter for Rockwell hardness tester needs to be calibrated by Vickers hardness tester. Due to ball indenter is smaller, it cannot be fixed on smooth test bed so that calibration cannot be carried out. Moreover, it is needed to refer to correction coefficient table after calibration, the corresponding results can only be obtained through interpolation method so that work efficiency is reduced. In terms of hardware, the mold for fixing ball indenter of Rockwell hardness tester is made by precise machining and selecting suitable materials to ensure the stability of ball indenter. In terms of software, the linear regression is performed based on the data in correction coefficient table to obtain fitted equation of correction values. Moreover, the correction table for hardness of convex sphere is edited with the formulas in the WPS table so that operation process of data processing is simplified. As a result, the calibration of hardness for ball indenter could be carried out so that the work efficiency and test accuracy could be improved.

The proportion of coking fly ash in mixed pulverized coal used in the production with rotary kiln of pellets could reach 15%, production with rotary kiln process is trouble-free and quality of pellets is stable by studying rotary kiln of pellets with coking fly ash. Moreover, the problem of environmental pollution caused by stockpiling of coking fly ash is solved, which provides a new way for effective treatment of coking fly ash. The fuel cost and production cost of pellets are effectively reduced by adding coking fly ash into mixed pulverized coal.

The old horse of 7^# blast furnace of Baotou Steel is deeper. In order to shorten the project duration and reduce workload of removing residual slag iron in furnace hearth after blowing out, the mode of dropping stockline and discharging residual liquid iron is adopted. It is one of the most important links in blowing out operation of blast furnace to discharge residual liquid iron and its effect directly affects the clearance time of furnace hearth. In the paper, the process of discharging residual liquid iron for 7^# blast furnace of Baotou Steel during blowing out is mainly introduced. The previous preparation work mainly includes such as activating furnace hearth, confirming position of residual liquid iron notch, calculating amount of residual liquid iron and making residual liquid iron runner. The cutting of shell of blast furnace and cooling stave, manufacture of mud sleeve for residual liquid iron notch as well as the whole process of discharging residual liquid iron after blowing out are introduced in detail. The process of discharging residual liquid iron of 7^# blast furnace is safe and ordered. After blowing out, it is found that there is basically no residual iron in the furnace hearth when cleaning it, which indicates that the effect of discharging residual liquid iron this time is good and experiences are gathered for discharging residual liquid iron in future heavy and medium repairs of blast furnace.

The accuracy of coal sample analysis depends not only on analysis technology itself, but also on accurate preparation of coal sample before analysis. The coal sample preparation is a complex process including a series of links such as crushing, mixing, division and preservation. The optimization of this process plays a decisive role in improving and ensuring the accuracy of analysis results. In current coal sample preparation process, such factors as segregation of particle size, sample contamination, drying time and improper preservation conditions could affect the representativeness of sample and accuracy of analysis results. In this paper, the preparation method and process optimization of coal sample are discussed. The quality and efficiency of coal sample preparation are improved by optimizing such processes as crushing, mixing, division and preservation, which could lay the foundation for improving the accuracy of analysis result for coal sanple.

The transformation structure and critical points of phase transformation for rare earth alloyed high carbon wear resistant steel as well as continuous cooling transformation (CCT) curve of undercooled austenite at different cooling rates are studied by metalloscope, field emission scanning electron microscopy and quenching dilatometer. The results showed that the critical points of phase transformation were Ac₁=742.6 ℃, Ac₃=816.5 ℃ and Ms=307.0 ℃. When cooling rate is less than 0.4 ℃/s, the microstructure is a small amount of ferrite+pearlite; when cooling rate is 0.4 ℃/s, the microstructure is single-phase pseudo eutectoid pearlite; when cooling rate is greater than 0.5 ℃/s, the microstructure is gradually transformed to martensite; when cooling rate is greater than 4 ℃/s, there is only the microstructure of martensite+retained austenite in the steel.

The drop weight tear test (DWTT) is used to test the toughness of materials, mainly for studying the low-temperature toughness of metal materials. In the paper, the microstructure and morphology of samples corresponding to different area proportions of brittle fracture are compared and analyzed with optical microscope aiming at the unqualified DWTT properties of products during trial production process of heavy gauge X80M hot rolled steel strip. The composition segregation in thickness direction of casting blank is tested. It is found that the severe segregation in thickness direction of steel strip is the main factor influencing the DWTT properties by analysis. The center segregation of casting blank and DWTT properties of product are improved effectively by adjusting the arc alignment precision of segment and optimizing the specific water amount of continuous casting machine so that the goal of stable production of hot rolled steel strip for heavy gauge X80M pipeline steel is realized.

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, the solution of unattended weighing system for automatically weighing materials transported by vehicles integrating the measurement and weighing, automation and computer technology is proposed. The system is with such functions as data acquisition, data sharing and remote transmission, voice command, vehicle localization, image capture and video monitoring so that the goal of unattended weighing and intelligent management of materials transported by vehicles is achieved. As a result, various problems such as high labor cost and labor intensity as well as falsification in traditional manual weighing mode are effectively solved.

The continuous cooling transformation laws of X120M pipeline steel is studied with Gleeble 1 500 thermal simulated test machine as well as it is with controlled rolling and controlled cooling in laboratory. The results indicated that the microstructure of test steel was mainly lower bainite and martensite when cooling rate was at 20~50 ℃/s. When the finish cooling temperature of test steel is at 380 ℃, its yield strength is 900 MPa, tensile strength is 1 015 MPa, elongation is 18%, impact energy at -30 ℃ is 180 J and shearing area of drop weight tear test at -20 ℃ is 100%. The mechanical properties could meet the standard requirements.

In this paper, the production practices on improving automatic casting ratio of ladle are introduced as well as various improvement measures are proposed through deeply analyzing the factors influencing automatic casting of ladle combining with production practices. The practices showed that the automatic casting ratio of ladle could be increased to over 99.5% so that the goal of reducing unplanned products produced by cast billets with burning oxygen is achieved through improving the quality of stuffing sand, optimizing sand filling device, formulating plan of replacing nozzle, strictly controlling time of steel filling according to steel grade, preventing back flow of steel slag and shortening standing time of liquid steel.