MI Guofa
,
NAN Hongyan
,
LIU Yanlei
,
ZHANG Bin
,
ZHANG Hong
,
SONG Guoxiang
钢铁研究学报(英文版)
Speed increase and heavy-haul of the railway freight car are the effective measures to raise the transport ability of railway, and they have been the new trend for railway freight car development. The increase of speed and axle load will lead to the increase of wheel-rail contact stress, which will make a great change of stress distribution in the whole wheel rim. Goodier equation was employed to analyze the stress state around inclusion and cavity. In the operation of wheel-rail contact stress, stress concentration occurred in the pole of Al2O3 spherical inclusion, while it appeared on the equator of cavity. The critical inclusion sizes of 25t axle load freight car wheel at different velocities, a certain distance away from the tread, were calculated by Murakami equation. By contrast the inclusion state in cast-steel wheel and rolled-steel wheel, the inclusion character in cast-steel wheel determined that it has much more excellent crack resistance than that of rolled-steel wheel. In the meantime, in order to reduce the probability of rim crack, some suggestions were put forward.
关键词:
heavy-haul;contact stress;critical inclusion size;rim crack
MI Guofa
,
LI Hongyu
,
LIU Xiangyu
,
WANG Kuangfei
钢铁研究学报(英文版)
The porous superalloy materials with hollow spherical pores were fabricated by using metal powder sintering process. The scanning electron microscope (SEM) observation was applied to the test samples and it revealed that the pores of the porous material exhibited a uniform distribution and the apertures were of same size in principle. The sintering necks appeared between adjacent particles on metal skeleton after sintering. The mechanical properties of the test samples were analyzed and the result showed that this kind of materials possessed excellent energy absorption capability, and the compression resistance decreased with increasing the porosity and aperture.
关键词:
porous superalloy material;metal powder sintering;hollow spherical pore;oriented linear pore
MI Guofa
,
LIU Xiangyu
,
WANG Kuangfei
,
FU Hengzhi
钢铁研究学报(英文版)
The numerical simulation technique was applied to the casting process of a valvetype part. The moldfilling and solidification stages of the casting were numerically analyzed. The filling behavior, solidification sequence, and thermal stress distribution were reproduced and the possible defects, such as cold shut and shrinkage, were predicted. Based on the simulation result, the doublegating system was replaced by a singlegating system. Meanwhile, the chills were used to regulate the solidification sequence of casting. To eliminate the cracks in the casting, the sand core was converted into a canulate one. By modifying the original process, the defects were eliminated and the casting with good quality was obtained.
关键词:
cast steel;valvetype part;numerical simulation;process modification
