WANG He-feng
,
TANG Bin
,
LI Xiu-yan
钢铁研究学报(英文版)
N-doped TiO2 (N-TiO2) coatings were obtained by oxidation of titanium nitride coatings, which were prepared by the plasma surface alloying technique on stainless steel (SS). The microstructure of N-TiO2 coatings was characterized by X-ray diffraction (XRD), glow discharge optical emission spectrometry (GDOES), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. Ball-on-disc sliding wear was applied to test and compare the tribological behaviors of the coatings and substrate. XRD patterns showed that anatase type TiO2 existed in the coatings after oxidation. GDOES showed that the resultant coatings had a layered structure, comprising of N-TiO2 layer at the top and a diffusion-type interface. Such a hybrid coatings system showed good adhesion with the substrate. According to XPS, residual N atoms partially occupied O atom sites in the TiO2 lattice. Uniform, continuous and compact coatings were observed by SEM images of coatings after oxidation. Under a load of 7.6 N, the coefficient of friction was in the range of 0.27-0.38 for the N-TiO2/Al2O3 systems and the wear rate of the coatings was only one-fourteenth of that for untreated 316L SS. N-TiO2 coatings displayed much better wear resistance and antifriction performance than SS substrate.
关键词:
plasma surface alloying technique
,
wear resistance
,
stainless steel
,
titanium dioxide
R Paventhan
,
P R Lakshminarayanan
,
V Balasubramanian
钢铁研究学报(英文版)
Friction welding is a solid state joining process used extensively currently owing to its advantages such as low heat input, high production efficiency, ease of manufacture, and environment friendliness. Materials difficult to be welded by fusion welding processes can be successfully welded by friction welding. An attempt was made to develop an empirical relationship to predict the tensile strength of friction welded AISI 1040 grade medium carbon steel and AISI 304 austenitic stainless steel, incorporating the process parameters such as friction pressure, forging pressure, friction time and forging time, which have great influence on strength of the joints. Response surface methodology was applied to optimize the friction welding process parameters to attain maximum tensile strength of the joint. The maximum tensile strength of 543 MPa could be obtained for the joints fabricated under the welding conditions of friction pressure of 90 MPa, forging pressure of 90 MPa, friction time of 6 s and forging time of 6 s.
关键词:
friction welding
,
stainless steel
,
response surface methodology
,
optimization
HUR Yone-gi
,
CHOI Young-kiu
钢铁研究学报(英文版)
The strip shape in the stainless steel process has made an issue of the strip quality. The objective of the shape control is to minimize the shape deviation and to maintain symmetrical shape patterns in the lateral direction. The method of the shape recognition employs the least square method. The shape deviation is controlled by the fuzzy shape controller (FSC). The experiments have been performed online for various stainless materials, thicknesses, and strip widths. The test results show very efficient performances in respect of stable target tracking and symmetrical and minimal fluctuation of the strip shape.
关键词:
shape control
,
fuzzy control
,
stainless steel
,
Sendzimir mill
