Process And Surface Enhancement Of Overlaying Welding For High Performance Continuous Casting Roller

Continuous casting roll is an important index to weigh the advanced nature of iron and steel industry.It plays a corresponding role in increasing steel output,reducing energy consumption and reducing pollution in iron and steel enterprises.At the same time,it has a certain impact on economic benefits.Its quality and life are important factors to be considered in continuous casting production,which directly affect the cost of products,the quality of billet and the operation rate of continuous casting machine.Steel mills consume a large number of continuous casting rollers every year.at the same time,because of the high price of continuous casting rollers,the production and management departments of enterprises pay more and more attention to the utilization and maintenance of continuous casting rollers.In this paper,the engineering problems of surfacing technology in the production of continuous casting roll are studied,and the selection basis and optimization principle of welding parameters such as roll body material and surfacing material,surfacing technology and post-weld heat treatment of continuous casting roll are studied.The blank inspection and preheating conditions before welding,the control of interlayer temperature,welding time and welding speed,the post-welding inspection and the selection of post-weld heat treatment process are systematically analyzed.Through the collation and analysis of multiple groups of experimental data,it is determined that the open arc surfacing process of multi-layer and multi-channel surfacing is adopted.The welding layer materials are ER309L（Mo）wire and ER316（L）wire in turn,and ring surfacing is used.The welding equipment selects roller cemented carbide surfacing equipment.When preheating before welding,the temperature should be controlled at 250 degrees Celsius,the thickness of surfacing layer should be strictly controlled at 2.5 degrees Celsius,and the temperature should not be less than 300 degrees Celsius during heat treatment.The first layer surfacing parameters are as follows:welding current 300³50A,voltage 24²8V,welding speed 120¹50mm min,roller diameter 1.2 mm,dry extension 25³0mm,eccentricity 5⁸mm,second layer surfacing parameters:welding current 360⁴80A,voltage 26³0V,welding speed 130¹80mm/min,the diameter of roller is 1.2 mm,the dry extension is 25³0 mm,and the eccentricity is 5⁸ mm.Aiming at the surface defects and internal discontinuity defects of continuous casting roller,the nondestructive testing,osmotic flaw detection and ultrasonic flaw detection of welding parts after welding are carried out.Referring to the corresponding standards,the defects should be repaired and re-examined in time.The microstructure analysis showed that the columnar crystals formed cellular dendrites on the surface of the transition layer,and the crystallization rate and composition undercooling increased with the decrease of temperature gradient.Due to the dispersion and distribution of nitride in the surface surfacing structure,the strength and hardness of the surfacing layer are improved,but the plasticity is not affected.The hardness of the welding part can reach 300HV_0.2and the tensile strength is 500N/mm²,which fully meets the practical requirements of the project.In this paper,considering the whole process,the surfacing process scheme of continuous casting roller consumed in practical engineering is optimized,and the excellent surface modification effect is obtained,which provides a reference for this kind of practical engineering problems.