CHENG Yongxing LI Genfu YU Shaoluo Shanghai University of Engineering Science
,
Shanghai
,
China WANG Huimin No.11 Institute of China State Shipbuilding Corp.
,
Shanghai
,
China Associate Professor
,
Dept.No.5
,
Shanghai University of Engineering Science
,
350 Xianxia Road
,
Shanghai
,
China
金属学报(英文版)
The Fe-Ni-Cr coating laver has been alloyed with 45 steel base metal by transverse.flow type CO_2 gas laser of maximum output 5kW.The characteristics of the melted zone and the es- sence of the“bright band”has been investigated using the electron microscopy.The results show that the“bright band”belongs to the melted zone and is a vertical section of the plane crystal,The width of the“bright band”equals the height of the plane crystal,which decreases with the increase of laser beam scanning rate and the decrease of laser power.This has been explained in terms of constitutional supercooling G/R.
关键词:
laser alloying
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null
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null
GAO Hua XUE Lijue Shanghai University of Engineering Science
,
Shanghai
,
China Associate Professor
,
Dept.of Materials
,
Shanghai University of Engineering Science
,
350 Xianxia Road
,
Shanghai
,
China
金属学报(英文版)
Hydrogen induced cracking(HIC)of 0.3% C,1% Cr,1% Mn,1% Si high strength steel has been studied under simple mode Ⅰ,mode Ⅱ and(Ⅰ+Ⅱ)mixed mode loading conditions.Af- ter being hydrogen-charged in IN H_2SO_4 solution,the material behaved hydrogen embrittlement in all the cases studied.The threshold K_(ⅡH)/K_(ⅡX) of HIC under mode Ⅱ load- ing was 0.27,which was nearly the same as that K(ⅠH)/K_(ⅠX)=0.29 under mode Ⅰ loading. While the thresholds of-HIC under(Ⅰ+Ⅱ)mixed mode loading were 0.36,0.41 and 0.37 cor- responding to the K_Ⅱ/K_Ⅰ ratio of 0.27,0.4 and O.81.The results show that simple mode Ⅰ or mode Ⅱ loading is more susceptible to hydrogen embrittlement than(Ⅰ+Ⅱ)mixed mode. For explaining the experimental results,the effects of triaxial stress as well as plastic deformation ahead of crack tip has been discussed.
关键词:
(Ⅰ+Ⅱ)mixed mode
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null
GAO Hua CHEN Youxuan LI Ming Shanghai University of Engineering Science
,
Shanghai
,
ChinaCHEN Dehai Shanghai Dalong Machinery
,
Shanghai
,
China Associate Professor
,
Dept.of Materials
,
Shanghai University of Engineering Science
,
Shanghai 200051
,
China
金属学报(英文版)
The effect of proportional and non-proportional overloading on mode l fatigue crack growth have been studied,and the influences of crack tip plastic zone,crack tip blunting as well as crack closure were discussed.Proportional(model I)overloading may cause more serious crack growth retardation than non-proportional(mixed mode)overloading.Therefore,for estimating the fatigue life of engineering structures to simplify a real overload which may of- ten be non-proportional as a proportional one is not always safe.
关键词:
non-proportional overloading
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null
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null
