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In order to improve the quality of welded joints and increase the service life of pipelines, ABAQUS finite element software was used to simulate the temperature field of 18,4 mm thick X80 pipeline steel in multi-layer and multi pass welding. The peak temperature of different passes was compared, and the change trend of temperature field in the welding process was obtained,. The results show that the peak temperature of the weld and its adjacent areas is higher, and the peak temperature of the weld center is the highest. Due to the fast welding speed, the heat cannot be transferred to other areas in time, resulting in uneven heating of the entire test panel.

Q345C steel is welded under two different pre-welding heating methods of traditional flame heating and ceramic sheet heating. The finite element analysis of the butt joint weldment by ABAQUS software is used to summarize the law of welding deformation and compare the welding quality under different pre-welding heating methods according to the residual stress and deformation trend of the welding joint weld. The results show that the main stress after welding is concentrated in the weld seam and the surrounding area. The residual stress after welding after the heating and welding of the ceramic sheet is significantly less than the residual stress after the traditional flame heating welding, and the welding after the heating of the ceramic sheet can obtain better welding quality.

According to the practical engineering application, three-dimensional modeling of electric hoist and I-beam track is carried out, and the model is simplified to determine the electric hoist load, roller acceleration and speed, and the Abaqus software is used to simulate, analyze the simulation results, observe the actual maximum load under the track stress and strain to meet the requirements, calculate the allowable stress, Observe whether it exceeds the allowable stress and whether plastic deformation occurs. If the numerical simulation results of stress and strain are within the safety requirements, the project can be implemented.

In this study, a 72-h neutral salt spray test was conducted on two low-carbon alloy steels and their corrosion kinetic equations were constructed, and tensile tests were conducted on specimens with different corrosion cycles to evaluate the mechanical properties of the two experimental steels. The test results showed that the corrosion resistance of TZ750MS was better than that of H750MS during the whole test cycle; however, the predicted results of the corrosion kinetic equation showed that the corrosion resistance of TZ750MS was lower than that of H750MS after 144 h. The tensile test results showed that the strength of both steels did not change substantially after corrosion, and the tensile stress-strain diagram showed that the specimens would fracture earlier after passing through the plastic deformation zone .

In order to meet the requirements for the quality of steel structure welding projects in severe cold areas, reasonable and effective technical research and welding scheme improvement are carried out for welding in low temperature environments. Based on ABAQUS software to simulate different welding conditions, mainly for welding after traditional flame heating and ceramic sheet heating in low temperature environment, the corresponding temperature field is obtained. Compared with the actual welding results, it is concluded that the weldment welded after heating with ceramic sheet is of better quality, fully verify the accuracy of welding simulation, optimize process design, shorten the time required for practical inspection accumulation.

Hot forging forming of railway wagon bogie adapter is a new railway wagon bogie adapter processing technology. In this paper, a hot forging die for railway wagon bogie adapter was designed, and the forming quality were analyzed by using DEFORM-3D software. Then, the feasibility of the process was verified by experiments. It was found that using this mold can eliminate the defects such as loose as-cast in metal smelting process, optimize the microstructure, forging products with good density, product quality and other characteristics of stability.

In order to accurately predict the flow stress of Q345B steel at high temperature, the Q345B steel was subjected to a hot compression test on the Gleeble-1500D thermal simulation test machine at a deformation temperature of 1 173,15~1 373,15 K and a strain rate of 0,01~10 s-1. Through the obtained true stress-strain curve, strain factors are introduced into the Arrhenius equation to establish a more accurate strain-coupled constitutive model. The results show that the correlation coefficient of the Arrhenius model considering strain compensation is 0,993, and the average absolute error is 4,59 %, which can accurately predict the flow stress. The experimental data and the calculated prediction curve fit well, which verifies the feasibility of the model.

To obtain the exact mechanical properties of TC4 titanium alloy, the compression experiments on TC4 titanium alloy at different strain rates (10-2,10-3,10-4 s-1) were performed at room-temperature on the MTS-810 electrohydraulic servo material testing machine. The data of TC4 titanium alloy compression experiments at different rates were obtained. And furthermore Johnson-Cook constitutive model is established. Due to different conditions, the equation is simplified, the constitutive parameters are obtained by step-by-step estimation method, and the Johnson- Cook (JC) constitutive model of TC4 titanium alloy at room temperature is established. The prediction results of the model were compared with the experimental data, the prediction curve is in good agreement, which verifies the feasibility of the model.

In the process of contemporary industrial pipeline installation, most pipelines must be cleaned before being put into use due to production and operation process requirements. This paper takes the offline trough cleaning of pipelines as the research object, and explores the evolution process of the metal microstructure under this cleaning method and the best cleaning conditions under the influence of the three factors of concentration, temperature and time.

In order to obtain the accurate mechanical properties of 7075 aluminum alloy, the Gleeble-1500D thermal simulation test machine was used to perform compression test on 7075 aluminum alloy. The deformation temperature range is 490 °C~560 °C, and the strain rate is 0,001 s-1~1 s-1. At present, for the high temperature thermal compression process, the Arrhenius constitutive model with strain compensation is usually used. The results show that the correlation coefficient of the Arrhenius constitutive model of 7075 aluminum alloy with strain compensation is 0,9894, and the average relative error is 5,6 %, realizing the fitting of flow stress and prediction, verified the feasibility of the model.

The downhole expansion process of the expansion tube is the dynamic deformation process of the expansion tube metal material at different temperatures. In this paper, the dynamic tensile test is used to measure the dynamic tensile stress-strain curve of low-carbon alloy steel in the temperature range of 25 – 300 °C. upon analyzed the dynamic tensile test results, with the strain rate factor Z and McCormick physical model, the paper set up low carbon alloy steel constitutive equation of underground temperature field. The calculation results of the Sellars creep equation are compared with the residual stress value after expansion in the finite element analysis of the solid steel pipe expansion to verify the actual application reliability of the steel for the expansion pipe with high expansion rate.

Thermal compression test temperature ranged from 800 to 1 200 °C, the strain rate ranged from 0,01 to 10 s-1, and the deformation degree was 60 % of engineering strain, the deformation behavior of 42CrMo gear steel was studied. As the deformation temperature increases and the strain rate decreases, the stress decreases significantly. By polynomial fitting the relationship between strain(0,05 – 0,9, at intervals of 0,05) and material constants, the straincompensationed Arrhenius constitutive equation for 42CrMo gear steel is established. The correlation coefficient between the experimental data and the predicted data reached 0,9925. This shows that the Arhenius constitutive equation has high accuracy in predicting steel 42CrMo for gear.