Microstructure And Properties Analysis Of Steel Wire Arc Additive Manufacturing For Construction Machinery

Steel is the most commonly used material in construction machinery due to its good mechanical properties,corrosion resistance,and high ductility.It is widely used in aerospace,petrochemical,automotive,mold,and medical equipment.The performance of steel for construction machinery generally requires good weldability,corrosion resistance,wear resistance and high strength.With the development of construction machinery towards large-scale,lightweight and heavy-duty products,the application and quality requirements of steel for construction machinery continue to increase.Arc Additive Manufacturing（Wire and Arc Additive Manufacture,WAAM）uses the arc as the heat source and the metal wire as the filling material to directly form metal solid components in a"bottom-up"layer-by-layer manner.Compared with traditional processing and manufacturing methods,it can The realization of high-performance,economical,environmentally friendly and rapid manufacturing has attracted more and more attention from the manufacturing industry.In this paper,the single-pass single-layer and multi-pass multi-layer additive manufacturing processes are explored through an additive manufacturing system with electric arc as the heat source,using MFA861M wear-resistant steel,ER2594 duplex stainless steel,ER316L stainless steel and ER308L stainless steel welding wire for additive experiments according to the application scenarios of different steels in construction machinery,respectively.The focus is on the formation characteristics,microstructure and mechanical properties of multi-pass multi-layer additive thin-walled walls to provide theoretical and data support for the arc additive manufacturing technology of steel for construction machinery.The main findings of this paper are as follows:Firstly,the microstructure and properties of the arc additive manufacturing samples of MFA861M wear-resistant steel were studied.The study found that during the molding process of the sample,there were small solid particles generated by splashing on the surface,and the macroscopic molding morphology was good.The microstructure observation is mainly ferrite;the transverse and longitudinal section microhardness distribution of the sample is uniform,and the average microhardness is 432 HV_0.2 and 437 HV_0.2 respectively;the transverse and longitudinal average tensile strength is 1057 MPa and 951 MPa respectively,but the toughness is poor,the transverse and longitudinal average elongation is 2.9%and 3.2%respectively,and the impact work at room temperature is 4 J and 6 J respectively.The average friction coefficient of the sample is about 0.6,and the wear amount increases with the increase of the load,and the wear rate of the sample is about 10^-6～10^-5g·（N·m）^-1 level,indicating that the wear-resistant steel prepared by arc additive has good wear resistance.Secondly,the microstructure and properties of ER2594 duplex stainless steel material arc additive manufacturing samples were studied.The results show that the sample prepared by wire arc additive manufacturing technology has good forming quality,no major defects,good metallurgical bonding inside the sample,and the microstructure is mainly ferrite,intragranular austenite,bainite,grain boundary austenite and secondary austenite.No harmful phases such as sigma-σand lambda-λhave been observed due to low heat input and suitable interlaminar temperature.The microhardness distribution of the transverse and longitudinal sections of the sample is uniform,and the average microhardness is 285 HV_0.2 and 301 HV_0.2 respectively;the sample has excellent mechanical properties,transverse yield strength 933 MPa,tensile strength 1013 MPa,elongation 27.7%,25℃Charpy impact value 229 J.Longitudinal yield strength 860 MPa,tensile strength 941 MPa,elongation25.2%25℃Charpy impact value 228 J.The electrochemical test results show that the sample has good corrosion performance.Then,the organization and properties of the ER316L stainless steel material specimens fabricated by arc additive manufacturing were investigated.The results show that the ER316L stainless steel specimens prepared by WAAM have good forming quality,no obvious defects,good metallurgical bonding inside the specimens,the microstructure is mainly austenite and a small amount of ferrite,the cross-sectional microhardness distribution is relatively uniform,the average microhardness of the transverse and longitudinal sections are 270 HV_0.2,267 HV_0.2,and the mechanical properties are excellent,The mechanical properties of the specimens are excellent,the transverse yield strength,tensile strength,elongation,and impact work are 324 MPa,583 MPa,44.7%,and 170 J,respectively.The self-corrosion potential Ecorr of-305m V and self-corrosion current density Icorr of 3.408×10^-6m A/cm² in Na Cl solution have good corrosion performance.Finally,the structure and performance of ER308L stainless steel arc additive manufacturing samples were studied,combined with the characteristics of arc additive manufacturing technology,the arc additive manufacturing technology was applied to practice,and the DF-17 model was planned to be printed for analysis and evaluation.The test results show that the sample has good forming quality,no obvious defects are found,the internal metallurgical bonding of the sample is good,the microstructure is mainly austenite,the cross-sectional microhardness distribution of the sample is relatively uniform,and the average cross-sectional The microhardnesses are 247 HV_0.2 and 239 HV_0.2 respectively.The mechanical properties of the samples are excellent.The transverse yield strength,tensile strength,elongation and impact energy are 380 MPa,604 MPa,65.5%,and 138 J respectively.The longitudinal yield strength,tensile strength,elongation,and impact energy are 352 MPa,565 MPa,67.5%,and 168 J respectively.The self-corrosion potential Ecorr of the specimen in 3.5%Na Cl solution is-343m V and the self-corrosion current density Icorr is 1.12×10^-5m A/cm² has good corrosion performance.the printing results of DF-17 model show that the arc additive manufacturing technology has a broad development application prospect.