Search Results (4)

Considering the problem of the weak bonding interface structure between the rolling mill oil and film bearing bushings of Babbitt alloy and steel substrate, a numerical simulation of the layered bimetallic ZChSnSb8Cu4/steel by tungsten inert gas (TIG)-metal inert gas (MIG) hybrid welding process was carried out using Simufact Welding software (version 2020). In this study, the TIG-MIG hybrid welding process was simulated to obtain the temperature field and the stress field distributions. The residual stress and the deformation of the weldment were also analyzed using the calculated results. The results showed that the temperature gradient and the thermal stress were reduced in TIG-MIG hybrid welding compared to the conventional MIG welding preparation of layered bimetal ZChSnSb8Cu4/steel, which resulted in an improvement in the structural stability of the weldment. The temperature field and deformation of TIG-MIG hybrid welding of Babbitt alloy were studied under different controlled electrode spacings and TIG welding currents, and it was found that as electrode spacing increased, so did heat loss. Furthermore, with increased TIG welding current, compressive stress increased and tensile stress at the weld decreased, and the maximum thermal efficiency of welding was with a preheating current of 60 A. Full article

High Cu-Pb-Sn, as the material for bimetallic cylinder block, is widely used in the selection of wear-resistant parts due to its excellent wear reduction, thermal conductivity, fatigue resistance, and strong bearing capacity, such as bearings and bearing bushes, aerospace pump rotor, turbine and guide plate, etc. However, because its wear resistance is not enough to meet the harsh conditions of high temperature, high speed, and heavy load, the research on high wear resistance Cu-Pb-Sn materials has important theoretical significance and application value for the application of bimetallic materials. ZCuPb₂₀Sn₅ alloy was taken as the research object to analyze the influence mechanism of its different microstructure and mechanical properties on the friction and wear properties of alloy materials. Friction experiments under two conditions of oil lubrication and dry friction were carried out on the MMW-1A pin-on-disc friction and wear testing machine. The wear resistance and wear mechanism of ZCuPb₂₀Sn₅alloy under the action of Cu₃P were discussed, and a high wear-resistant Cu-Pb-Sn alloy for bimetal cylinder block was prepared. The results show that with the increase of P content, both the friction coefficient and wear rate decrease, and the wear reduction of ZCuPb₂₀Sn₅ alloy increases. Under oil lubrication conditions, the friction coefficient decreases by 21.4% and the wear rate decreases by 85.5% compared with that without adding P. The friction-reducing and wear-resistant properties of ZCuPb₂₀Sn₅ alloy materials are increased. In dry friction and oil lubrication, the mass wear amount of ZCuPb₂₀Sn₅ alloy material decreases with the increase of P element addition, and the change rule of alloy wear amount is consistent under the two methods. In the process of friction and wear, adhesive wear occurs, and the wear amount of the alloy material increases. With the increase of P content, the lead particles are refined and evenly distributed, which promotes the formation of a uniform self-lubricating lead film during the friction process and reduces the degree of adhesive wear. The appearance of Cu₃P reduces the contact area of the friction surface and weakens the adhesive wear, so the wear rate is reduced. Full article

High lead–tin bronze is widely used in the selection of wear-resistant parts such as bearings, bearing bushes, aerospace pump rotors, turbines, and guide plates because of its excellent wear resistance, thermal conductivity, fatigue resistance, and strong load-bearing capacity. At present, high lead–tin bronze is used as a material for bimetal cylinders, which cannot meet the requirements of high-strength, anti-wear in actual working conditions under high temperature, high speed, and heavy load conditions, and is prone to de-cylinder, cylinder holding, copper sticking, etc. The reason for the failure of cylinder body parts is that the strength of copper alloy materials is insufficient, the proportion of lead in the structure is serious, and the wear resistance of the material is reduced. Therefore, it has important theoretical significance and application value to carry out research on the comprehensive properties of high-performance lead–tin bronze materials and reveal the strengthening and toughening mechanism. In this paper, The ZCuPb20Sn5 alloy is taken as the main research object, and the particle size, microstructure, mechanical properties, and friction of lead particles in ZCuPb20Sn5 alloy are systematically studied after single addition of B in ZCuPb20Sn5 alloy liquid. This paper takes ZCuPb20Sn5 alloy as the research object to study the effect of adding B on the morphology, microstructure, mechanical properties, and friction and wear properties of ZCuPb20Sn5 alloy lead particles, and discusses the strengthening and toughening mechanism of ZCuPb20Sn5 alloy under the action of B, and prepares a double high-performance lead–tin bronze alloy for metal cylinders. The main research results are as follows: The addition of B elements has an obvious refining effect on the α (Cu) equiaxed grains and lead particles in ZCuPb20Sn5 alloy. The average size of lead particles decreases from 30.0 µm to 24.8 µm as the B content increases from 0 wt.% to 0.1 wt.%. The reason for grain refinement is that B is easily concentrated at the grain boundary during the ZCuPb20Sn5 alloy solidification process, which affects the diffusion of solute atoms at the solidification interface, inhibits the grain growth, refines the grain, and hinders the sinking and homogenizes distribution between dendrites of lead; the tensile strength of the ZCuPb20Sn5 alloy improves. Relatively without B, when the addition of P is 0.1 wt.%, the tensile strength is the largest at 244.04 MPa, which enhances 13%; the maximum hardness gets 75.0 HB, which enhances 13.6%, as well as elongation get the maximum value at 17.2%. The main mechanism is that the addition of B forms a high melting point submicron Ni₄B₃ phase in the lead–tin bronze alloy. The Ni₄B₃ phase is dispersed in the matrix and strengthens the matrix. With the increase in B content (more than 0.1 wt.%), the Ni₄B₃ phase changes from sub-micron degree granular to micron degree block-like, and some defects such as shrinkage and porosity appear in the structure, resulting in a decrease in mechanical properties. Full article

The current study introduces a method for manufacturing steel–aluminum bearing bushings by compound forging. To study the process, cylindrical bimetal workpieces consisting of steel AISI 4820 (1.7147, 20MnCr5) in the internal diameter and aluminum 6082 (3.2315, AlSi1MgMn) in the external diameter were used. The forming of compounds consisting of dissimilar materials is challenging due to their different thermophysical and mechanical properties. The specific heating concept discussed in this article was developed in order to achieve sufficient formability for both materials simultaneously. By means of tailored heating, the bimetal workpieces were successfully formed to a bearing bushing geometry using two different strategies with different heating durations. A metallurgical bond without any forging defects, e.g., gaps and cracks, was observed in areas of high deformation. The steel–aluminum interface was subsequently examined by optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). It was found that the examined forming process, which utilized steel–aluminum workpieces having no metallurgical bond prior to forming, led to the formation of insular intermetallic phases along the joining zone with a maximum thickness of approximately 5–7 µm. The results of the EDS analysis indicated a prevailing Fe_xAl_y phase in the resulting intermetallic layer. Full article