Zhuang Li Di Wu
材料科学技术（英）
The machinability tests were conducted by using a YD-21 dynamometer on a CA6161A lathe. The experiments were conducted to determine the effect of free-cutting additives on machining characteristics of austenitic stainless steels. The conventional austenitic stainless steel 1Cr18Ni9Ti (steel A) and the free cutting austenitic stainless steel (steel B) were prepared. The results have shown that machinable inclusions were composed of MnS and CuO, and they might be also Ti4C2S2. The presence of Bi in the inclusion was detected by the atom map and electro-probe microanalysis (EPMA), which might be one of the most important factors to improve the machinability of austenitic stainless steels. The cutting forces for steel B were lower than those of steel A at various cutting speeds; the abrasion depth of theflank of the tool for steel B was less than that of the steel A under the same cutting conditions. The machinability of austenitic stainless steel was visibly improved by adding free-cutting additives, such as S, Cu and Bi. Ultimate tensile, yield strength, and total elongation values of the free cutting austenitic stainless steel were improved due to the addition of these free-cutting additives.
关键词:
Austenitic stainless steel
,
free-cutting additives
,
bismuth
,
machining characteristics
,
the mechanical properties.
A. Momeni
材料科学技术（英）
Thermomechanical processing as a combination of cold rolling and annealing was performed on austenitic stainless steels 301, 304 and 304L. Two cold rolling steps each one up to a reduction of 75% were combined with an intermediate annealing at 800°C for 20 min. The final annealing was performed at the same temperature and time. Cold rolling contributed to martensite formation at the expense of metastable austenite in the studied materials. Austenite in 30l was found to be less stable than that in 304 and 304L. Hence, higher strength characteristics in the as-quenched 301 stainless steels were attributed to the higher volume fraction of martensite. Both α′-martensite and ε-martensite were found to form as induced by deformation. However, the intensity of ε-martensite increased as the stability of austenite decreased. Annealing after cold rolling led to the reversion of austenite with an ultra fine grained structure in the order of 0.5-1 μm from the strain induced martensite. The final grain size was found to be an inverse function of the amount of strain induced
martensite. The thermomechanical processing considerably improved the strength characteristics while the simultaneous decrease of elongation was rather low.
关键词:
Austenitic stainless steel
Feng Shi
材料科学技术（英）
Precipitation behaviors of Fe-18Cr-18Mn-0.63N and Fe-18Cr-18Mn-2Mo-0.69N high-nitrogen austenitic stainless steels during isothermally aging at 850°C have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The experimental results show that precipitation displays a discontinuous cellular way and the precipitates are identified as Cr2N in Fe-18Cr-18Mn-0.63N steel. The addition of Mo makes precipitation occur not only at the grain boundary but also inside the grain and precipitation also displays discontinuous cellular way. The precipitates at the grain boundary and in the cell are both identified as Cr2N phase and χ phase and the precipitates inside the grain are identified as Χ phase in Fe-18Cr-18Mn-2Mo-0.69N steel. The nucleations of Χ phase and Cr2N phase at the grain boundary are both governed by the diffusion of Cr atoms. The formation and growth of χ phase inside the grain are induced by the impoverishment of N atoms with increasing aging time.
关键词:
Austenitic stainless steel
Zhuang Li Di Wu
材料科学技术（英）
The machinability tests were conducted by using a YD-21 dynamometer on a CA6161A lathe. The experiments were conducted to determine the effect of free-cutting additives on machining characteristics of austenitic stainless steels. The conventional austenitic stainless steel 1Cr18Ni9Ti (steel A) and the free cutting austenitic stainless steel (steel B) were prepared. The results have shown that machinable inclusions were composed of MnS and CuO, and they might be also Ti4C2S2. The presence of Bi in the inclusion was detected by the atom map and electro-probe microanalysis (EPMA), which might be one of the most important factors to improve the machinability of austenitic stainless steels. The cutting forces for steel B were lower than those of steel A at various cutting speeds; the abrasion depth of theflank of the tool for steel B was less than that of the steel A under the same cutting conditions. The machinability of austenitic stainless steel was visibly improved by adding free-cutting additives, such as S, Cu and Bi. Ultimate tensile, yield strength, and total elongation values of the free cutting austenitic stainless steel were improved due to the addition of these free-cutting additives.
关键词:
Austenitic stainless steel
,
free-cutting additives
,
bismuth
,
machining characteristics
,
the mechanical properties.
A. Momeni
材料科学技术（英）
Thermomechanical processing as a combination of cold rolling and annealing was performed on austenitic stainless steels 301, 304 and 304L. Two cold rolling steps each one up to a reduction of 75% were combined with an intermediate annealing at 800°C for 20 min. The final annealing was performed at the same temperature and time. Cold rolling contributed to martensite formation at the expense of metastable austenite in the studied materials. Austenite in 30l was found to be less stable than that in 304 and 304L. Hence, higher strength characteristics in the as-quenched 301 stainless steels were attributed to the higher volume fraction of martensite. Both α′-martensite and ε-martensite were found to form as induced by deformation. However, the intensity of ε-martensite increased as the stability of austenite decreased. Annealing after cold rolling led to the reversion of austenite with an ultra fine grained structure in the order of 0.5-1 μm from the strain induced martensite. The final grain size was found to be an inverse function of the amount of strain induced
martensite. The thermomechanical processing considerably improved the strength characteristics while the simultaneous decrease of elongation was rather low.
关键词:
Austenitic stainless steel
Chuan PAN
,
Zhengbang LI
,
Zhiling TIAN
,
Dongtu LIANG
,
Lijie QIAO
,
Wuyang CHU
材料科学技术（英）
For 308L and 347L weld metals of austenitc stainless steels (ASS), hydrogen induced cracking (HIC) occurred during dynamically charging under constant load. The threshold stress intensity for HIC, KIH, decreased linearly with the logarithm of the concentration of diffusible hydrogen C0 in the weld metals and the rolled plate of type 304L ASS, i.e., KIH=85.2-10.7ln C0 (308L),KIH=76.1-9.3ln C0(347L), and KIH=91.7-10.1ln C0(304L). The fracture mode for HIC in the three type of ASS changed from ductile to brittle with the decrease in the applied stress intensity KI or/and the increase in C0. The boundary line between ductile and brittle fracture surfaces was KI-54+25exp(-C 0/153)=0.
关键词:
Austenitic stainless steel
,
null
,
null
Huaming WANG
,
Xijun SUN
,
Xiaoxuan LI
材料科学技术（英）
An austenitic stainless steel 1Cr18Ni9Ti and a solid solution-strengthened Ni-base superalloy GH30 were shock processed using a Q-switched pulsed Nd-glass laser. Microstructure, hardness and residual stress of the laser shock processed surface were investigated as functions of laser processing parameters. Results show that high density of dislocations and fine deformation twins are produced in the laser shock processed surface layers in both the austenitic stainless steel and the nickel-base superalloy. Extensive strain-induced martensite was also observed in the laser shock processed zone of the austenitic steel. The hardness of the laser shock processed surface was significantly enhanced and compressive stress as high as 400 MPa was produced in the laser shock processed surface.
关键词:
Laser shock processing
,
null
,
null
,
null
