On-line Monitoring Of Argon Arc Remelting Of H13 Steel And Study On The Effect Of Isothermal Treatment

In the service process of hot working die,local defects such as wear and deformation will occur,thus shortening the service life of the die.Therefore,the modification and strengthening of the die surface is a key link in the die industry.Argon arc remelting technology is a common technology for surface strengthening treatment and repair of die.At present,the most common manual repair methods are inefficient and rely too much on the experience and technology of the operator,which leads to the unstable quality of the surface strengthening and repair of die.In this paper,based on the original argon arc remelting equipment,an arc height feedback adjustment system is developed by using machine vision technology.The slope remelting test of H13 steel is carried out by using this system,and the influence of isothermal treatment on the microstructure and mechanical properties of argon arc remelting H13 steel is studied.The aim of this work is to provide theoretical support and practical guidance for the automation field of argon arc remelting strengthening and repair on the surface of H13 steel die.Machine vision algorithm is used to extract the height of arc image after preprocessing.The radial distortion coefficient and tangential distortion coefficient are obtained by calibrating the camera.The graying,image filtering,binarization threshold segmentation algorithms are analyzed and studied.Through the comparison and analysis of the experimental results of arc image preprocessing algorithm,the algorithm which is most suitable for this system and the corresponding parameters are selected,including the gray image using the average method,the median filter for image denoising and the manual threshold segmentation binarization image to achieve image segmentation.Through comparative study,it is determined that more accurate arc height can be obtained when the gray threshold is 200,which improves the accuracy of arc height recognition.Based on obtaining arc height,an automatic argon arc remelting monitoring system is designed.According to the characteristics of arc height measurement,the selection of hardware and the design of hardware and software are completed.The selection design of hardware mainly includes camera,lens,stepper motor and Arduino board.The software part is based on the Labview platform,including the design of graphic processing algorithm and human-computer interaction interface,to realize the PID feedback adjustment of the height of the welding gun.The slope remelting test was carried out using the above automatic argon arc remelting monitoring system,and the influence of isothermal treatment temperature on the modified argon arc remelting layer of H13 steel was studied.The phase,microstructure,residual stress,microhardness,nano-hardness,elastic modulus and tribological properties of H13 steel remelted layer samples prepared at 250 ℃,300 ℃,350 ℃ and under air cooling conditions were analyzed.The results show that with the increase of isothermal temperature,the residual stress,hardness and wear properties of the sample at room temperature decrease.Considering the service environment of the hot work die steel,the remelted sample at 250 ℃isothermal treatment has the best comprehensive properties.