Chunju WANG
,
Debin SHAN
,
Bin GUO
,
Jian ZHOU
,
Lining SUN
材料科学技术（英文）
From the viewpoint of production engineering, microforming is considered as an effective process to fabricate various microparts. Several key problems in microforming processes were investigated. A new microforming apparatus with a high stiffness piezoelectric actuator as the punch driver was developed to produce microparts. To improve the forming abilities and locate the billets, a floating microdie was designed. The size effects of the billets and die cavities on the microforming abilities were studied with upsetting and coining tests, respectively. And the isothermal microforming process of microgears was performed with the developed microforming apparatus. Several analysis methods were used to evaluate the forming quality of the microparts.
关键词:
Microforming
,
尺寸效应
,
微塑性成形设备
,
浮动
WU Su-zhou
,
ZHANG Jiong-ming
,
LI ZHi-zheng
钢铁研究学报(英文版)
The SEN clogging is a long term issue for all the steelmakers. In the current study, the kinetics of SEN clogging during steel continuous casting was established. The dynamic build-up of alumina inclusions to the lining refractory of SEN was analyzed. The fluid flow and inclusions motion are calculated by means of mathematic model. Effect of diameters of inclusions, roughness of nozzle, diameter of nozzle and casting speed on the entrapment probability are estimated.
关键词:
nozzle clogging;mathematic model;inclusion motion
Optics and Lasers in Engineering
Aero-engine overhaul calls for low-cost and high-quality method to solve the failure of structural members. This paper presents a pulsed-laser cladding (repair coating) of near alpha titanium alloy used for structural member repairing and investigates the microstructures, microhardness and wear resistance of the repair coating. The repair coating is mainly composed of alpha' martensite. The center region of the melting zone formed by each single pulse is characterized by micro-acicular martensite. At the margin, the microstructure shows columnar morphology. With a simplified model of laser cladding, the formation of columnar morphology is discussed. Compared with the substrate, the repair coatings show near performances on microhardness and wear resistance, and decrease the wear of lining pads dramatically in same condition. The different performances between repair coatings and substrate are mainly attributed to the different microstructures and the diffusive behaviors of 0, C, and other elements. The results above indicate that, it is feasible to repair the near alpha titanium alloy structural members by pulse-laser cladding. (C) 2008 Elsevier Ltd. All rights reserved.
关键词:
laser cladding;titanium alloy;repair;microstructure;wear resistance;oxygen-permeation;high-temperature
