Papers by Author: Hong Wei Liu

Abstract: Microstructure and mechanical properties of 22MnB5 Steel were analysis with different heat treatment experiment. The result show that the martensite lath with water cooling become smaller than that with metal die cooling, The lath martensitic microstructure is disappeared with die cooling & tempered specimen. The tensile strength reaches the highest 1645.34MPa by water cooling, but the plastic strength product is lowest. Q&P and die cooling & tempering process can improve the elongation of 22MnB5 with a small amount of tensile strength decrease. The plastic strength product reaches the highest of 20312.74MPa•% by die cooling & tempering method.

Abstract: The microstructural evolution of of as-cast ZK60 magnesium alloy processed by cyclic extrusion and compression (CEC) were studied, and the effects of technical parameters on microstructural evolution were investigated. The results show that the grains of as-cast ZK60 magnesium alloy were obviously refined and uniformed by CEC, the average grain size was decreased from original 50 ~ 60 μm to about 2 μm when the extrusion ratio was 8 with 8-passes at 350°C, and the refinement effect was increased with the rising of extrusion ratio and passes. The effect of increasing passes on grain refinement was not obvious when it exceeds 8. Nevertheless, it is beneficial for the grain homogenization.

Abstract: The forming limit diagram of clad was developed with Hill’s instability criterion and M–K analysis at the positive strain ratio. The relationships of forming limit with stain path, thickness ratio and thickness irregular coefficient were analyzed. The results show that the forming limit of clad material is between those of its component materials, and increase with the rising of stainless steel thickness ratio and the thickness irregular coefficient. The most suitable value of f0 is 0.094 and the stainless steel aluminum clad break with local interfacial cracks.

Abstract: Laser bending process of sheet metals is a highly flexible forming technique. Simulate model of laser bending process was established by dimension analysis, and the control model of laser bending was achieved with the regression of swatch datum. It was shown that dimension analysis was an effective method in simulating the complex laser bending process, and the control model, which came from non-dimension group datum, was a high-accuracy model in predictive analysis of bending angle.

Abstract: The interface is the area where two type of materials are connected, the strength and property of interface are important for the application of the clad. In this paper, interfacial strength and fracture properties of stainless steel-aluminum clad are analyzed with the methods of interfacial shear test and four point bending test, and the interfacial crack and the interfacial fracture structure are analyzed with SEM. The results show that the bonding of stainless steel and aluminum is successfully realized by explosive welding, the interfacial shear strength reach 70.90MPa, and the interfacial energy release rate is 1.725 MPa•m, the thickness of transition layer is about 10μm at the interface, the interfacial fracture happen and extend in the transition layer along the interface and the interface fracture structure is inclined to brittle fracture.