钢铁
Home
|
About Journal
|
Editorial Board
|
Instruction for Authors
|
Subscriptions
|
Advertisement
|
Contacts Us
|
Chinese
Office Online
Author Center
Peer Review
Editor Work
Office Work
Editor-in-chief
Journal Online
Forthcoming Articles
Current Issue
Archive
Read Articles
Download Articles
Email Alert
Quick Search
Advanced Search
2021 Vol. 56 No. 3
Published: 2021-03-15
Technical Reviews
Materials
Technical Reviews
1
LI Xiao-bing, DONG Xin, XING Wei-wei, CHEN Bo, LIU Kui, MA Ying-che
Effect of alloying elements addition on the secondary tempering brittleness of Cr-Mo steels review
For some Cr-Mo steels (2.25Cr1Mo) which are usually serviced at medium temperature for a long time,the critical problem of the second type temper embrittlement is existed in these steels because of the continuous segregations of P,S and other harmful impurities to the grain boundary during the service. In order to explore some effective methods to reduce the temper embrittlement tendency of this kind of Cr-Mo steels and improve the reliability of the material,starting from the segregation mechanism of solute elements,the intrinsic essences of alloy elements segregation at grain boundary and its function on improving the temper brittleness of steel were analyzed. The segregation phenomena of several common elements and their influence on temper embrittlement of steel were mainly summarized. At the same time,the main reasons for the difference between theoretical calculation and experimental study are also analyzed. It is expected to provide some effective methods for temper embrittlement of medium temperature steel during long-term service,and offer some references for the study of grain boundary segregation behavior of alloying elements in future.
2021 Vol. 56 (3): 1-12 [
Abstract
] (
307
) [
HTML
1KB] [
PDF
2493KB] (
1032
)
13
LI Shao-hong, HE Wen-chao, ZHANG Xu, LI Dong-hui, XIAO Mao-guo
Research progress on surface treatment technologies of H13 hot work die steel
In the industry,deformation,wear and fatigue failure of molds are common,which seriously affects production efficiency and production line safety. In order to better understand and analyze the causes of mold failure,improve the performance of the mold and increase its service life,the surface treatment technologies and current research status of H13 hot work die steel were introduced. The characteristics and researched results on improving surface properties of hot work die steel including laser heating treatment,thermal spraying treatment and chemical heat treatment were summarized. In addition,the effects of different surface treatments on the surface properties of hot work die steel were discussed and the advantages and disadvantages of different surface treatment technologies applied to improve the surface properties of hot working die steel were analyzed. Moreover,the development trends of surface treatment technologies on hot work die steel were prospected.
2021 Vol. 56 (3): 13-22 [
Abstract
] (
297
) [
HTML
1KB] [
PDF
4925KB] (
685
)
Materials
23
WANG Shuai, CHEN Wei-jian, ZHAO Zheng-zhi, ZHAO Xiao-long
Microstructure and properties as well as deformation behavior in an incritical annealing medium-Mn steel
In order to investigate the evolution rule of microstructure of medium manganese steel and its influence on mechanical properties and deformation behavior in an intercritical annealing treatment, a cold-rolled medium manganese steel (0.1C-7Mn-0.35Si) was intercritically annealed from 570 to 650 ℃. The research results show that as the annealing temperature increases, the dual-phase structure containing of austenite plus ferrite structure gradually tends to be equiaxed and the grains become coarsened, and the martensite structure appears at 650 ℃. The tensile strength of the experimental steel increases with increasing temperature, while the elongation and yield strength all show a downward trend; the localized uneven deformation band was gradually weakened and was completely disappeared at 620 and 650 ℃. When annealed at a relatively high annealing temperature, the stimulative deformation-induced martensite transformation inside coarse equiaxed austenite grains and the reduced dynamic recovery in large-sized ferrite grains, as well as the introduction of martensite at higher temperature etc. all enhance the work hardening capability at the yield stage, and hence recede or suppress the propagation of the Lüders band.
2021 Vol. 56 (3): 23-28 [
Abstract
] (
325
) [
HTML
1KB] [
PDF
4059KB] (
731
)
29
ZHANG Bo, MENG Li, ZHANG Ning, HE Cheng-xu, MA Guang, HU Zhuo-chao
Effect of recrystallization annealing temperature on texture and magnetic properties of ultra-thin oriented-silicon steel
In order to study the effect of annealing temperature on microstructure,texture and magnetic properties of ultra-thin grain-oriented silicon steel for medium/high frequency application,an ultra-thin grain-oriented silicon steel with a thickness of 0.08 mm was prepared by the primary recrystallization method using the commercial 0.27 mm glassless grain-oriented silicon steel plate as raw materials. Effects of annealing in the range of 800 ℃ to 1 000 ℃ on annealed structure,texture and magnetic properties of ultra-thin oriented silicon steel were systematically investigated. It was found that,due to forming high-angle misorientation grain boundary with surrounding deformation matrix,the η oriented ({0
kl
}<100>) grains in transition bands preferentially nucleated by bulging of initial grain boundaries. With the increase of annealing temperature,average recrystallized grain size increased,the size advantage of non-η oriented grains such as {114}<481> grains became more obvious,the volume ratio of η oriented grains decreased and grain uniformity turned worse. Ultra-thin oriented silicon steel had better comprehensive magnetic properties when annealing temperature was slightly lower and the magnetic induction intensity and the core loss was 1.82 T and 11.66 W/kg respectively,best comprehensive medium frequency magnetic properties in the present experiment condition when annealing temperature was 800 ℃.
2021 Vol. 56 (3): 29-33 [
Abstract
] (
316
) [
HTML
1KB] [
PDF
2779KB] (
899
)
34
PANG Yang, ZOU De-ning, LÜ Xiang, LI Miao-miao, YAN Xing-yu
Effect of manganese on microstructure and properties of high nitrogen super martensitic stainless steel
In order to further improve the strength and toughness and excellent corrosion resistance of super martensitic stainless steel,two new super martensitic stainless steels with nitrogen of 0.35% and manganese of 0.4% and 2.0%(mass percent) were developed and prepared under laboratory conditions,which are processed by quenching and partitioning process; The microstructure and mechanical properties of the steel were characterized by universal testing machine,optical microscope,scanning electron microscope,transmission electron microscope and electron backscattering diffraction. The results show that the mechanical properties of the two kinds of test steels are significantly improved compared with that of typical super martensitic stainless steels after quenching and partitioning. At the same time,it is found that manganese has a significant influence on the strength and toughness of the test steel. When the mass percent of manganese increases from 0.4% to 2.0%,the tensile strength and elongation of the test steel change from 1 690 MPa and 15.2% to 1 215 MPa and 35.1%,respectively,which both break the strength and toughness indexes of traditional super martensitic stainless steel. It is concluded that the reason for the significant improvement of strength and toughness is that the retained austenite content increases significantly after quenching and partitioning due to the synergistic effect of nitrogen and manganese,which is also caused by the precipitation of nano-scale reversed austenite and nitride.
2021 Vol. 56 (3): 34-40 [
Abstract
] (
220
) [
HTML
1KB] [
PDF
4589KB] (
713
)
41
YANG Yue-biao, LI Zong-qiang, DENG Shen, FAN Lei, LIU Qing-you, ZHAO Zheng-zhi
Low temperature impact toughness controlling for Ti-microalloyed high strength steel
To solve the problem of inferior low-temperature impact toughness of hot-rolled titanium microalloyed high-strength steel,the reasons were analyzed from the aspects of impact fracture morphology,second phase of TiN and metallographic structure by means of the optical microscope,the scanning electron microscope,the energy dispersive spectrometer and other devices combined with thermodynamics and kinetics calculation. The analysis results showed that the main reasons for the inferior low-temperature impact toughness of the test steel are as follows. The presence of large particles of the second phase of TiN in steel,serious pearlite banded structure and uneven size distribution in steel,the effect of large TiN particles was more significant. By adding the processes of KR hot metal desulfurization and RH refining,improving the secondary cooling strength of continuous casting,reducing the mass percent of C,N in steel and other optimization measures,and therefore,the size of large TiN particles was reduced,the grade of pearlite banded structure in steel was reduced,as well as the proportion of soft phase structure of ferrite and the microstructure uniformity were increased. The low-temperature impact toughness of hot-rolled titanium microalloyed high-strength steel was improved significantly and the qualified rate was increased to 100%.
2021 Vol. 56 (3): 41-50 [
Abstract
] (
760
) [
HTML
1KB] [
PDF
2744KB] (
1080
)
51
ZHOU Ren-yuan, ZHU Li-hui, KE Zhi-gang, LI Shi-xian, ZHAI Guo-li, SONG Ming
Effect of tempering temperature on impact absorbed energy of modified T23 steel
The safety of ultra-super critical power plants is severely endangered by the high reheat-cracking susceptibility of T23. Our former experimental results showed that the reheat cracking susceptibility of modified T23 steel was highly improved by modifying the composition,but the impact absorbed energy decreased. In order to improve the impact absorbed energy of modified T23 steel, the effect of tempering temperature on the microstructure,hardness and impact absorbed energy of modified T23 steel was investigated in this paper. The hardness and impact absorbed energy of modified T23 steel after tempering at 750-810 ℃ were measured,and the microstructure was analyzed by optical microscope (OM),scanning electron microscope (SEM) and transmission electron microscope (TEM). The result shows that with increasing tempering temperature,the hardness of modified T23 steel decreases,while the impact absorbed energy increases firstly and then decreases. After tempering at 790 ℃,the impact absorbed energy reaches the maximum value. The main reasons for the decrease of hardness are the softening of matrix,the decomposition of M-A constitutes and the widening of bainitic laths. Compared with tempering at 750 ℃,the number of M-A constitutes with large size in modified T23 steel after tempering at 790 ℃ decreases,and the size is smaller. There are still some M
23
C
6
carbides with small size at the grain boundaries, and the degree of bainitic lath widening is low. The crack propagation is hindered effectively,hence the impact absorbed energy is the highest. When the tempering temperature is increased to 810 ℃,the number of small M-A constitutes decreases and a large number of M
23
C
6
carbides dissolve. In particular,the retarding effect of crack propagation is further reduced due to the severe widening of bainitic laths. Therefore,the impact absorbed energy decreases.
2021 Vol. 56 (3): 51-57 [
Abstract
] (
262
) [
HTML
1KB] [
PDF
3895KB] (
724
)
58
LIN Peng-fei, YANG Zhong-min, CHEN Ying, LI Zhao-dong
Rust layer of weathering steel and its stabilization treatment status
Weathering steel has good atmospheric corrosion resistance,but the formation of stable rust layer is slow. Pretreatment of the surface of weathering steel before use can shorten the formation time of rust layer stabilization and prevent rust liquid from sagging. The development of weathering steel at home and abroad,the formation process of stabilized rust layer and the composition and structure of rust layer are briefly summarized. The rust layer is divided into loose outer rust layer dominated by γ-FeOOH and dense inner rust layer dominated by α-FeOOH. The mechanism of rust layer protection is introduced,including physical barrier,anodic passivation protection,corrosion inhibitor protection and ion selective penetration protection. In order to explore the best use of weathering steel,the current application methods of weathering steel are summarized,which are mainly used after exposed,coated and rust stabilized. The key points of stabilizing treatment for rust layer of weathering steel are put forward,that is,selecting suitable film forming materials and accelerants to promote the formation of α-FeOOH. The application and development direction of stabilization treatment technology in the future are prospected.
2021 Vol. 56 (3): 58-65 [
Abstract
] (
470
) [
HTML
1KB] [
PDF
792KB] (
861
)
66
NING Xiao-zhi, XING Chang-jun, YONG Qi-long, WU Lin
Effect of nitrogen contentration on hardening and softening properties of high nitrogen stainless steel
High-nitrogen nickel-free austenitic stainless steels with different mass percent of nitrogen from 0.02% to 1.20% were designed and melted. The effect of nitrogen on work hardening and annealing softening were investigated through mechanical properties test and microstructure examination. The results show that nitrogen enhances the rate of work hardening. The work hardening rate increased 7.06 MPa/% when the mass percent of nitrogen raise from 0 to 1.2%. Nitrogen can promote recrystallization nucleation, refine grain size effectively. The grain refined 60% with mass percent of nitrogen adds from 0.4% to 1.2%, but it can diversify grain orientation.
2021 Vol. 56 (3): 66-70 [
Abstract
] (
288
) [
HTML
1KB] [
PDF
3139KB] (
699
)
71
ZHANG Ying-bo, ZOU De-ning, WANG Quan-sheng, ZHANG Xiao-ming, LI Yu-nong
Effect of silicon on microstructure and properties of ferritic heat-resistant steel
The 18Cr-Al-Si ferritic heat-resistant stainless steel as a new type of structural connection material is mainly used in the field of supercritical or ultra-supercritical thermal power generation. In order to clarify the influence of Si content on the structure and properties of this steel,based on 18Cr-Al-Si ferritic heat-resistant stainless steel,the Si content of two groups of different components is added.Through the test methods such as room temperature tensile test and high temperature oxidation test,meanwhile,with the help of metallurgical microscope(OM),scanning electron microscope (SEM) and X-ray diffractometer (XRD) and other characterization methods,the structure and properties of different Si content test steels were systematically analyzed. The results show that the increase of Si content will refine the grain size of ferrite and increase the amount of M
23
C
6
,the tensile strength and yield strength of the test steel will increase,and the elongation will decrease. The fracture mode will change from ductile to tough-brittle mixed mode. 1.35Si steel has greater mass gain,this is because more M
23
C
6
carbides are precipitated in the steel,thereby reducing the content of Cr dissolved in the matrix and forming the oxide film,and decreasing its high-temperature oxidation resistance.
2021 Vol. 56 (3): 71-76 [
Abstract
] (
267
) [
HTML
1KB] [
PDF
3297KB] (
678
)
77
HAN Yun, QIU Mu-sheng, ZOU Ying, WANG Gang
Precipitates, microstructure and properties of Ti-IF steel with high plastic strain ratio
In order to study the effect of hot rolling and final product precipitates on the plastic strain ratio of Ti-IF steel, The precipitation behavior of micro-alloyed carbides during hot rolling and galvanized annealing of two Ti-IF steels at different hot-rolling heating temperatures were studied by universal testing machine, transmission electron microscope (TEM), energy dispersive spectrometer(EDS) and electron backscattered diffraction(EBSD) analysis methods combined with thermodynamic calculation. The results showed that the size of the precipitates of hot-rolled coils increased with the decrease of hot-rolling heating temperature, the size of the precipitates of Ti
4
C
2
S
2
and its composite with Cu
2
S increased from 50-100 nm to 100-200 nm. The precipitates are mainly spherical or ellipsoidal distributed in a cellular or continuous chain-like form. With the reduction of sulfur content, hot-rolled coils heated at 1 230 ℃ contain more TiC precipitates with size of 10-20 nm, which can be retained after annealing in galvanizing, while TiC particles are rarely found in hot-rolled or galvanized coils at higher sulfur content. That is, more coarse Ti
4
C
2
S
2
can be precipitated at higher sulfur content while the precipitation and growth of fine TiC is inhibited. The {111} surface texture ratio of galvanized coil with higher sulfur content reached more than 87.5%, therefore it′s exhibiting higher plastic strain ratio in terms of mechanical properties.
2021 Vol. 56 (3): 77-83 [
Abstract
] (
241
) [
HTML
1KB] [
PDF
4388KB] (
515
)
84
WANG Hong-tao, TIAN Yong, YE Qi-bin, WANG Zhao-dong, WANG Guo-dong
Development of heavy-gauge steel with excellent brittle crack arrest toughness for mega container carriers
For the excellent brittle crack arrest toughness,the heavy-gauge steel for mega container carriers can significantly reduce the hazard factor caused by complex alternating stresses on a large opening structure on the upper deck. By systematically summarizing the evaluation system of crack arrest toughness,comparing and analyzing the development trend of mega container carriers at home and abroad as well as the production status of heavy-gauge crack arrest steel,the microstructural characteristics and possible production process are summarized. The fine-grained equiaxed ferrite,polygonal ferrite,limited refined bainite,combined with the strengthened texture along with the γ orientation at 1/2 thickness are the keys to improving the crack arrest toughness. The NEU-Rolling process proposed by Northeast University can solve the existing problem of producing heavy-gauge steel by a traditional controlled rolling process.
2021 Vol. 56 (3): 84-91 [
Abstract
] (
329
) [
HTML
1KB] [
PDF
4745KB] (
668
)
92
LIU Dong-sheng, CHENG Bing-gui, LUO Mi, QU Jin-bo
Microstructures and mechanical properties in ultra-thick EH47 steel plates and heat affected zones
A microalloyed low carbon MnCrNiCu steel has been proposed to develop EH47 steel plates via thermomechanical controlled processing(TMCP) route. The effect of hot deformation of austenite or cooling rate on phase transformation in the steel was investigated. Heavy steel plates with maximum thickness of 85 mm were rolled. Submerged arc welding(SMA) and flux-cored arc welding(FCAW)processes were employed in welding trials,respectively, to evaluate the weldability of the thickest plate. Microstructures in the plates and the coarse-grained heat affected zone(CGHAZ) were characterized. Ductile-to-brittle transition temperatures(DBTTs) in the plates were measured based on a series of instrumented Charpy V notch(CVN) impact tests, followed by the determination of the local cleavage fracture stresses(
σ
f
). Microhardness and CVN impact toughness in the heat affected zone(HAZ) produced by either SMA or FCAW were also tested. Full thickness crack tip open displacement(CTOD) in the mother plate or the weld joints was tested at -10 ℃ leading to evaluation on the crack-initiation toughness(
K
c
) in the ultra-thick plate or the weld joints. A temperature dependency of crack-arrest toughness(
K
ca
)in the ultra-thick plate was determined based on a series of large scale double tension(DT)tests across the entire thickness of the ultra-thick plate. The results show that:a mixture of polygonal ferrite(PF)+acicular ferrite(AF)associated with dispersed martensite-austenite constituents was produced in the plates. An increase in
σ
f
leads to a decrease in DBTT. The critical events of cleavage fracture during the CVN testing and DT crack arrest testing are identical being grain-sized cracks. In comparison with the CGHAZ where quasi-polygonal(QPF)+AF are produced by SMA,cleavage crack can be initiated more easily in the CGHAZ by FCAW due to the formation of brittle GB. As a result,
K
c
associated with the latter CGHAZ is lower than the former.
K
ca
at -10 ℃ is determined being 7 140 N/mm
3/2
indicating satisfactory crack arrestability in the mother plate.
2021 Vol. 56 (3): 92-102 [
Abstract
] (
349
) [
HTML
1KB] [
PDF
9506KB] (
605
)
103
SUN Man-yi, TAN Yi, WANG Yi-lin, ZHUANG Xin-peng, ZHANG Feng, WANG Yi-nong
Effect of electron beam melting on carbide of high speed steel
The fine and dispersed carbides are the guarantee of the excellent performance of high-speed steel, but the complex alloy composition leads to coarse carbides and severe segregation in the as-cast high-speed steel. In order to explore the effect of electron beam melting on as-cast high-speed steel and improve the structure and carbide state of high-speed steel, electron beam melting technology to prepare M35 high-speed steel and characterize its composition and structure was used. The results show that the average dendrite spacing in EBM-M35 high-speed steel is 20 μm, the size of carbides is fine, and they are evenly distributed in the structure. The main types are MC and M
2
C, and the M
2
C carbides change from lamellar to fibrous. During heat treatment of as-cast EBM-M35 high-speed steel, it was found that the carbide fractured and spheroidized after being kept at 1 180 ℃ for 30 min to achieve the effect of refining the carbide and dispersing the carbide in the structure. Furthermore, the fracture and spheroidization of carbides in EBM-M35 high-speed steel can be completed at a lower temperature or shorter heat treatment time, and the microstructure optimization of as-cast high-speed steel can be completed at a lower cost. It provides a more excellent basis for the deformation and refinement of as-cast high-speed steel.
2021 Vol. 56 (3): 103-110 [
Abstract
] (
211
) [
HTML
1KB] [
PDF
5079KB] (
528
)
111
WANG Ping, HUANG Hua-qin, LI Xiang, XIE Qian, HOU Qing-yu, HUANG Zhen-yi
Mechanical behavior of an as-forged austenite-based low-density steel under high-speed impact loading at cryogenic temperature
In order to evaluate the ability of the as-forged austenite-based low-density steel to resist high-speed impact loading at low temperature,a low-temperature and high-speed impact test using a Split Hopkinson Pressure Bar (SHPB) apparatus at -50 ℃ and engineering strain rate of about 4 300 s
-1
was carried out on an as-forged austenite-based low-density steel sample of Fe-28.13Mn-10.04Al-1.05C (Mn28Al10) with dimensions of
ø
3.94 mm×2.88 mm. The mechanical behavior of the steel at low-temperature and high-speed impact loading was studied. The result showed that,the impacted sample experienced elastic deformation of about 18 μs,compression plastic deformation of about 110 μs,tensile plastic deformation of about 20 μs and fracture under the above-mentioned experimental process. The plastic energy and the adiabatic temperature rise of the impacted sample before fracture were about 1 558 J/cm
3
and 178 ℃,respectively. The stress-strain curve of the impacted sample showing a typical strain-strengthening characteristic,and the existence of adiabatic temperature rise made the stress-strain curve showed fluctuation phenomenon. The impacted sample was broken down into three fragments,which were induced mainly by compression plastic deformation and tensile plastic deformation. The fracture showed compression zone and tensile zone,both of which belong to ductile fracture characterized by the dimple. The substructures of the deformation zone near the compression zone and the tensile zone were all high-density movable dislocations. The dislocation density of the compression deformation zone is lower than that of the tension deformation zone,and the length and width of the high-density dislocation in the compression deformation zone were larger than that in the tension deformation zone. The deformation mechanism of the as-forged austenite-based low-density steel of Mn28Al10 at -50 ℃ and engineering strain rate of about 4 300 s
-1
was dislocation slip.
2021 Vol. 56 (3): 111-119 [
Abstract
] (
278
) [
HTML
1KB] [
PDF
2794KB] (
760
)
120
SUN Zhen-duo, HOU Dong-bo, LI Wei, ZHANG Ming-yang
Influence of notch on fatigue properties of nitrided CrNiW steel in very high cycle regime
In order to study the influence of notch sensitivity on fatigue properties of nitrided CrNiW steel,a smooth specimen and two notched specimens with concentration factor
K
t
=1.20 and
K
t
=1.55 were designed,respectively. The very high cycle fatigue tests were carried out by using nitrided CrNiW steel. The microstructure of the fatigue specimen was observed by SEM. The relationship of notch fatigue factor
K
f
,notch sensitivity index
q
and number of cycles to failure
N
f
were analyzed. The results show that,the case-nitriding has little effect on the improvement of fatigue strength of steel. For the smooth specimen and the notch specimen with
K
t
=1.20,the failure modes can be classified as surface induced failure and the interior induced failure where the defects are limited in the non-nitriding area. For the notch specimen with
K
t
=1.55,interior failure induced by the inhomogeneous matrix area within the nitrided layer is observed,which is a new failure characteristic. The duplex
S
-
N
property of smooth specimen is not obvious. However,there is a duplex
S
-
N
property with surface induced failure and interior induced failure as
K
t
=1.20,and there is a duplex
S
-
N
property only with surface induced failure which occurs in the short life regime and the VHCF regime as
K
t
=1.55. With the increase of
K
t
,the phenomenon of multiple interior crack sites is replaced by the single interior crack site,and the interior defect position gradually moves towards the surface of specimen,and the shape of fisheye first approximately exhibits the oblate with major axis at
x
direction,followed by the circular shape,and then the elliptical shape with major axis at
y
direction. The
K
t
has a large effect on fatigue life with surface failure,but has a little effect on fatigue life with interior failure.
2021 Vol. 56 (3): 120-129 [
Abstract
] (
235
) [
HTML
1KB] [
PDF
8160KB] (
643
)
130
ZHANG Xiong, YU Wei, WANG Yun-long
Phase transformation model of 38MnSiVS non-tempered steel
For hot-rolled non-tempered steel bars, the transformation microstructure after rolling has an important influence on the mechanical properties of the final products. In order to predict the microstructure evolution and properties of 38MnSiVS non-tempered steel bar after hot rolling accurately, the dynamic continuous cooling transformation (CCT) curve and dynamic isothermal transformation (TTT) curve was measured respectively using a thermal expansion method with a Gleeble-3500 thermal simulator and a Dil805 quenching dilatometer and analyzed by quantitative metallographic method of the microscopy. The effect of cooling rate on the phase transformation and pearlite interlamellar spacing was studied and analyzed, based on the Esake and Pietrzyk and Zener and Hillert models, then the relationships between the ferrite grain size d
α
and pearlite interlamellar spacing
S
P
were established. In addition, combined with the data of dynamic isothermal transformation curve and Scheil superposition principle, the volume of ferrite is calculated theoretically, which is helpful microtructure and property control technology for hot rolling production.
2021 Vol. 56 (3): 130-136 [
Abstract
] (
312
) [
HTML
1KB] [
PDF
5749KB] (
756
)
137
XIA Yong, SHEN Hou-fa, LIU Hua-song, WANG Pu, TANG Hai-yan, ZHANG Jia-quan
Dendritic morphology and characteristic parameters during solidification of Fe-C alloy with phase field model
In order to realize the quantitative characterization of the dendrite morphology during the alloy solidification process,reveal the influence of solute distribution and undercooling on the microsegregation in the solidification front,and then carry out the quantitative study of the liquid phase permeability between solidification dendrites,the phase field model is adopted to discuss the microstructure and characteristic parameters of Fe-0.5%C alloy during solidification,and the fractal dimension and dimensionless circumference were introduced to quantitatively analyze the dendrite morphology,microsegregation and mush zone permeability. The results show that the fractal dimension and dimensionless circumference can be used to estimate the complexity of dendrite morphology quantitatively. The fractal dimension increases from 1.28 to 1.791,and the dimensionless circumference increases from 2.39 to 12.6 when the undercooling increases from 20 to 27 K. With increasing undercooling,the solute concentration in both the central axis of dendrite and the solid/liquid interface increase,and the diffusion layer thickness at the dendrite tip decreases,i.e.,the segregation ratio between dendrites increases. Taking as the tortuosity factors of the dendrite in liquid,the fractal dimension and dimensionless circumference were used to estimate the mush permeability during solidification. Compared the fractal dimension,the dimensionless circumference is reliable in estimating the permeability with the value of 1.36×10
-15
-1.75×10
-13
m
2
for the given undercoolings.
2021 Vol. 56 (3): 137-145 [
Abstract
] (
222
) [
HTML
1KB] [
PDF
3635KB] (
631
)
146
XIE Yu-min, SONG Ming-ming, MEN Chao-qi, ZHU Hang-yu, MA Guo-jun, XUE Zheng-liang
Influence of Ca treatment on application of rare earth in HAZ during high heat input welding progress
To make clear the influence of Ca treatment on the effect of Rare Earth (RE) to improve the toughness of Heat Affected Zone (HAZ) in C-Mn steel,Gleeble was used to simulate the welding thermal cycle process with a heat input of 339 kJ/cm. The differences in inclusion,microstructure and low-temperature impact toughness in HAZ between RE treated steel and Ca-RE treated steel were compared. At last,the influence of Ca on the role of RE in HAZ was studied. It was found that Ca can promote the function of RE to improve the low temperature impact toughness in HAZ. The inclusions in HAZ of RE treated steel transformed from complex inclusions containing RE
x
O
y
to that of RE and Ca when treated with Ca,thereby decreasing the total amount of inclusions. Ca treatment also resulted in the increase in the mean size of the inclusions from 1.5 to 2.2 μm,while a decrease in the aspect ratio from 1.5 to 1.4. Although Ca had little effect on the content of acicular ferrite in HAZ of RE-treated steel,however,the inhibition of RE on prior austenite grain coarsening in HAZ was enhanced by Ca treatment,with a smaller grain size than that of the RE treated steel. The low-temperature impact toughness in HAZ of RE treated steel was obviously improved by Ca treatment When the heat input was 339 kJ/cm.
2021 Vol. 56 (3): 146-153 [
Abstract
] (
260
) [
HTML
1KB] [
PDF
3779KB] (
747
)
154
JIN He-rong, ZHANG Zhao-rui, HAN Min-feng, YI Ya-li, ZHAO Ding-xuan
Effect of nickel interlayer thickness on characteristics of 316L/EH40 composite interface
In order to explore the influence of interlayer thickness on the microstructure and properties of composite materials, four kinds of composite samples with different thickness of Ni interlayer (0.05, 0.10, 0.15, 0.20 mm) were set up. Hot compression test of samples with the same thickness ratio was carried out under the same conditions. The microstructure of the interface after compression was analyzed by metallographic microanalysis technology, and the diffusion of elements at the interface was analyzed by energy spectrum analysis. The mechanical properties of the interface were tested by microhardness test and the tensile properties of the material were tested by tensile test. The results show that with the increase of the thickness of the nickel interlayer, the bonding interface became smooth, and the barrier effect of diffusion of carbon, chromium and other elements became better. When the thickness reached a certain degree, the mechanical properties of plate decreased with the increase of interlayer thickness. Besides, the hardness value near the 0.05 mm Ni layer appeared obvious mutation, and the change trend of hardness value near the other three thicknesses of interlayer was almost the same. Among them, the diffusion behavior of elements could be block well by the 0.10 mm thick Ni interlayer, and the excellent tensile property(512 MPa) at the interface of materials could also be ensured.
2021 Vol. 56 (3): 154-163 [
Abstract
] (
230
) [
HTML
1KB] [
PDF
5619KB] (
522
)
钢铁
News
·
·
·
·
·
More
Author Center
Instruction for Authors
Template
Copyright Agreement
Links
·
Links
More
Copyright © IRON AND STEEL
Supported by: Beijing Magtech
