| The dimond frame saw blade is the main component for cutting marble,It is a thin and long steel body,The brazing temperature is low to control the thermal deformation during brazing.At the same time,The dimond frame saw blade is subjected to the combined stress of horizontal cutting force and vertical shearing force during the using.It requires excellent mechanical properties of brazing joints.Some products work in a high temperature environment and take longer time.They require high fatigue properties of the saw steel.Five silver brazing filler metals were selected to meet the above requirements.Two kinds of three element brazing filler metals,Including HL312 and BAg612.Two kinds of four element brazing filler metal,Including CT643 and BAg616.In addition,the Layered composite filler metal HL861 was selected.The effects of silver brazing filler metals on mechanical properties and microstructure of marble saw steel were investigated by different brazing process.It was found that the mechanical properties of the four element brazing filler metal are better than that of four element brazing filler metal.This is because the four element brazing filler metal contains a small amount of Ni and Mn elements,and Ni and Mn are toughening elements.Although the Cd element in the five element brazing filler metal can significantly reduce the melting temperature and improve the fluidity and spreading performance of the solder,the addition of Cd can also make the solder brittle and reduce the mechanical properties.The impact toughness of the sandwich solder HL861 is higher.The Layered composite filler metal can withstand a certain degree of impact load and is suitable for brazing material of marble frame saw blade.The fatigue properties of five kinds of brazing materials have been found that The fatigue properties of the three element brazing filler metal CT643 and BAg616 are obviously better than that of the four element solder brazing filler metal HL312 and BAg612.The solder BAg616 can still exceed the fatigue cycle base 2×106 without breaking at high stress amplitude,and fatigue performance is the best.When the stress amplitude of sandwich filler metal HL861 gradually decreases,the cycle times of fatigue fracture always stabilize at a certain level without showing linear.The results may be influenced by the interlayer of the copper.The fatigue fracture surfaces of fatigue cracks,fatigue bands and fatigue bands appeared in five kinds of solder joints.A large number of dimples appear in the final fracture zone of fatigue cracks,The fatigue fracture ischaracterized by quasi dissociation and intergranular fracture.The fatigue fracture factors include the surface state of the specimen,the loading properties of the load and the internal inclusions,and the existence of these factors can be found on the fatigue fracture.The metallurgical structure of brazed joints is divided into five parts,It includes saw steel body zone,reaction interface layer,brazing heat affected zone,brazed joint zone,diamond interface layer and diamond lump.The brazed joint is straight and has good bonding with the metal on both sides,without pores and inclusions,and the width of the brazed joint is about 0.2mm.the microstructure of the brazing seam becomes smaller and finer With the increase of brazing temperature.Grey black and white tissue interweave more closely,and the tissue's toughness is further strengthened.EDS composition analysis showed that the gray white phase was rich Ag solid solution,and the gray black phase was Cu rich solid solution. |
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