Study On The Influencing Factors Of Welding Material Toughness Of GX8CrNi12 Cast Steel

GX8CrNi12 cast steel belongs to martensite heat-resistant cast steel.It has good toughness,high temperature strength,high temperature performance and stability of the organization,resistance to vapor corrosion and high-temperature oxidation resistance.Because this material does not belong to the existing conventional stainless steel classification,domestic literature is rarely reported;In Europe,there are welding consumables with similar compositions.However,domestic welding consumables are still in blank.Therefore,it is necessary to research and develop matching welding consumables to meet customer needs.This subject is based on the Balmforth phase composition map,and the chemical composition of the electrode is designed to achieve the purpose of controlling the deposition of the metal deposition structure of the welding wire.The test uses XRD test(X-ray diffraction test)and conventional optical microscope analysis of the metallographic structure,using the impact test to evaluate the weld metal deposited metal toughness.Finally according to the gas protection wire characteristics and requirements,the test reference electrode test results to design gas shielded wire Chemical composition(MAG welding wire);During the MAG welding test,it was found that by adjusting the welding process parameters to change the welding heat input,there is a difference in the impact toughness of the welding wire cladding metal.By measuring the welding heat cycle curve of MAG welding and using high-temperature metallographic experiments,the influence mechanism of welding heat input(mainly on the influence of welding speed on welding heat input)on the impact toughness of deposited metal of welding wire is analyzed to determine a reasonable welding process parameter.The results show that: GX8CrNi12 belongs to martensite heat-strength cast steel,the welding material deposited metal structure is mainly composed of martensite + a small amount of ?-ferrite.The impact toughness of the deposited material of the welding material mainly depends on the ?-ferrite content.With the increase of the ?-ferrite content,the impact toughness of the deposited metal decreases.when the welding material deposited metal does not exist ?-ferrite,the impact toughness can reach the best.It can effectively control the content of ?-ferrite in the tissue that appropriately adjust the main chemical elements of chromium and nickel content in the deposited metal of the GX8CrNi12 steel electrode which reasonably reduce the Cr content and increase the Ni content.During the welding test of the gas shielded welding wire,it was found that by appropriately reducing the welding speed,the impact toughness of the deposited metal can be improved.The reason is that the reduction of welding speed can promote the transformation of ?-ferrite to austenite and eventually form the structure of martensite,thereby reducing the content of ?-ferrite in the deposited metal of the welding wire at room temperature and improves the toughness of the deposited metal.