Time filter

Source Type

Luo Z.F.,Guizhou University | Luo Z.F.,Guizhou key Laboratory for Mechanical Behavior and Microstructure of Materials | Luo Z.F.,Performance Technology | Liang Y.L.,Guizhou University | And 11 more authors.
Materials Science and Engineering A | Year: 2017

The cyclic quenching with both the rapid heating and cooling was applied on 51CrV4 spring steels by a DIL805A/D dilatometer. The microstructures were observed by a scanning electron microscope (SEM) and a transmission electron microscope (TEM), whereas the strengthening mechanism of the test steels was discussed by the general equation of p0.2 i=σ0+Δσp i+Δσr i+ΔσT i. The results demonstrated that the grain size was the lowest with only 1.76 µm, the area fraction of the twins was the highest up to 6.78% and the thickness of the twins was fined to 11.71 nm at six times. Also, an excellent comprehensive performance was obtained, such as the yield strength, the tensile strength and the area reduction of the test steels was increased substantially as the cyclic quenching was conducted from 1 to 6 times, where the maximum values were up to 1792.93 MPa, 2036.2 MPa and 44%, respectively. As a result, the strength increase was mainly attributed to the ultra-refine grain formation, the area fraction increase of the micro-nano scale twins and the size refinement decrease; whereas it was observed that the highest contribution to the strength and ductility was from the micro-nano scale twins. © 2017


Li C.,Guizhou University | Li C.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | Yao Z.,Guizhou University | Liang Z.,Guizhou University
Advanced Materials Research | Year: 2011

Continuous casting process parameters such as casting speed, superheat, secondary cooling water flow rate have greatly affections to central defects in SWRH82B billet. These parameters were investigated by the methods of chemical content analysis and etch test for macrostructure in some steel plant of china. The results shows that the central defect of SWRH82B billet can be improved when the superheat is controlled at the range of 15∼25°C, casting speed is 1.80m·min-1 and secondary cooling water flow rate is 0.72 L·kg-1. © (2011) Trans Tech Publications.


Li X.,Guizhou University | Li X.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | Liang Y.,Guizhou University | Liang Y.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | And 2 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2014

Effect of forced air cooling rate on microstructure and mechanical properties of 70 steel wire was investigated. The results show that the tensile strength and the reduction of area of the steel wire increase with the increasing of the forced air cooling rate. This is because the interlamellar spacing and colony size of pearlite decrease when the cooling speed increases. The elongation of the steel wire is influenced by the uniformity of the microstructure, and more uniform microstructure results in a higher elongation. The tensile strength and the reduction of area of 70 steel wire austenitized at 860°C and cooling at 250°C/s are better than that by patenting treated.


Zhang Z.,Guizhou University | Zhang Z.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | Zhao F.,Guizhou University | Zhao F.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | Tan W.,Guizhou University
Jinshu Rechuli/Heat Treatment of Metals | Year: 2014

The influence of quenching-isothermal (Q-I) and quenching-isothermal-tempering (Q-I-T) processes on microstructure and mechanical properties of 60Si2CrVA steel was studied by SEM, optical microscopy, X-ray stress analyzer, MTS and so on, and compared with the traditional treatment. The results show that the 60Si2CrVA steel treated by Q-I process has fine comprehensive mechanical properties, tensile strength is 2142 MPa, the percentage reduction of area is 42.17%, and the impact absorbed energy is 43.3 J. The duplex microstructure with many retained austenite and bainite obtained by Q-I is the main factor to improve the toughness and ductility.


Wang P.,Guizhou University | Wang P.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | Liang Y.,Guizhou University | Liang Y.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | And 4 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2014

Effect of normal force (F), displacement amplitude (δd) and cycle number (N) on the fretting wear behavior of 35CrMo steel was investigated at ambient temperature by the self-made fretting wear test apparatus. The fretting wear mechanism was discussed. The results show that the three parameters fully effect the fretting wear behavior of 35CrMo steel. With one parameter increased, the wear loss is aggravated. The change of friction coefficient reflects that wear is serious in the initial stage of the experiment and then is tended to gentle. Adhesive and abrasive wear can be observated by the wear scar morphology. The wear mechanism is delamination and third body wear mechanism.


Zhu J.,Guizhou University | Zhu J.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | Yang C.,Guiyang University | Jiang Y.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | And 3 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2016

Under the same quenching process (910 ℃×30 min), influence of different tempering temperature (400-520 ℃) on microstructure and mechanical properties of 60Si2CrVAT spring steel was investigated. The results show that quenched at 910 ℃ for 30 min and tempered at 430 ℃ for 60 min, the strength and toughness of the steel is best. With tempering temperature increased from 400 ℃ to 520 ℃, the strength and hardness of the steel decrease, and the elongation and contraction of cross sectional area first increase and then decrease. When tempering temperature is 430 ℃, the strain hardening exponent reaches the maximum value 0.086. The microstructures of spring steel tempered between 400 ℃ and 520 ℃ are tempering troostite, and needle-shaped ferrit tends to grow up and the residual austenite is decomposed with the temperature increasing. © 2016, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved.


Zhang Z.,Guizhou University | Zhang Z.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | Zhao F.,Guizhou University | Zhao F.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | Shi Y.,Guizhou University
Jinshu Rechuli/Heat Treatment of Metals | Year: 2014

The 18Ni (1700 MPa) maraging steel was treated by variable-temperature circular grain fining which was based on the theory of reversed austenite recrystallization, and the fining behavior of cyclic phase transition grain fining on crystal degree and sub-structure were analyzed, the effect of grain fining on fracture toughness and the common mechanical properties was investigated. The result suggests that the fining process achieves the fining of crystal degree and sub-structure at the same time, and it also significantly improves strength, ductility and toughness of the steel. However there is no distinct effect on the fracture toughness of the 18Ni maraging steel by grain fining, and the grain size and aspect ratio of martensite lath are the main two factors to influence the fracture toughness.


Zeng H.,Guizhou University | Zeng H.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | Xiang S.,Guizhou University | Xiang S.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | And 2 more authors.
Corrosion Science and Protection Technology | Year: 2014

Electrochemical performance was studied for 904L stainless steel after solution treatment at different temperatures in concentrated sulfuric acid by means of measurements potentiodynamic polarization curve and cycle polarization curve. The results show that the solution temperature has little effect on cathodic process, but varies the anodic polarization curve greatly. Whilst 904L stainless steel shows the best corrosion resistance after solution treatment at 1120 °C for 0.5 h.


Huang C.,Guizhou University | Huang C.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | Liang Y.,Guizhou University | Liang Y.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | And 5 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2013

Microstructure and fatigue properties of 211Z.X heat-resisting high strength and toughness aluminum alloy under T6 heat treatment condition were studied. The fatigue fracture surface was analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show that the fatigue limit of the alloy is 154.25 MPa and its range from 147.13 MPa to 140 MPa when the survival rate P is from 50% to 99.9%. Fatigue cracks are often found to initiate from Ce-rich rare earth particles and Fe-rich intermetallic particles, which are located near the subsurface of the specimens. It also shows that fatigue cracks propagate radially as a transcrystalline and intercrystalline mixed propagation mechanism.


Ren Y.-H.,Guizhou University | Zhao F.,Guizhou University | Zhao F.,Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials | Yan Y.,Guizhou University
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2013

Influence of heating temperature and holding time on the grain growth of 18Ni(1700 MPa) maraging steel were studied. The grain growth model of 18Ni maraging steel has been established by regression with experiment data and the applicability of the model is verified. The results show that grain evolution experiences three stages when holding at temperature of 930-1070°C inverted austenitic recrystallization incubation period, inverted austenitic recrystallization process and recrystallized grain re-growing. The grain is refined obviously in recrystallization process. The refined grains will grow up again at a high speed after the tens of seconds of the recrystallization of reverted austenite, the higher temperature, the higher the grains growth rate, and the grains growing rate is reduced with the increase of holding time. The predictive and measured grain size coincides rather well.

Loading Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials collaborators
Loading Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials collaborators