Research Of Liquid-liquid Bimetal Composite As-cast Relieving

The practical working condition of Excavator relieving is very serious. The Excavator relieving not only bears the wear effect, but also is affected by certain impact loads while dredging. Every year, the damage due to abrasion and impact fracture of our country can not be turned a blind eye to. According to the actual working conditions of the relieving and its property requirements, nine groups of chemical composition were designed and a complete set of heat treatment process and composite process scheme was put forward.The microstructure, mechanical properties and phase constitution of the prong material was respectively analyzed by mechanical performance test, optical microscope, impact detection wear tester and scanning electron microscopy and found that the microstructure was organized by lower bainite, residual austenite and a small amount of martensite. Considering comprehensive mechanical properties of the sample, the best ratio of chemical composition(wt %) of tooth is C: 0.5, Cr: 3.5, Si: 1.2, Mn: 1.6, Mo: 0.3, Ni: 0.5. The optimum heat treatment process is preserving at 950℃ for 1.5 hours and the austempering process is keeping 2 hours at 300℃. Under the best ingredients and the optimal process, the hardness range of the relieving tooth material is from 46 HRC to 55 HRC, raising 8 HRC compared to the original in relieving, and the impact toughness is ak≥30J/cm2.The bimetallic composite shovel teeth was produced through two furnace smelting and analysis of the impact tester, micro hardness tester, XRD, SEM, optical microscope bimetal cutter were used to obtain the optimal complex parameters. The pouring temperature of double metal composite process is 1480℃ and the pouring time is 20 s. The composition of tooth handle parts is C: 0.33, Cr: 1.22, Si: 1.2, and Mn: 1.83, in which some expensive elements were saved. Under the same heat treatment process, the tooth handle hardness range is from 36 to 40 HRC, and the impact toughness is ak ≥60J/cm2.A new theory--compound mixture theory--was proposed in this the design. Since the interface is curved, it increased the composite interface bonding area, and the interface stress is no longer a single direction when the relieving works, thus it improved the interface bonding strength and was a new idea for bimetallic composite. From the design of the bimetal compound casting relieving capacity test, the service life is more than 1.5 times higher than that of active relieving, and the problems of relieving easy to fracture and easy to wear in use process were solved successfully.