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1.
To investigate the hot deformation behavior of powder-forged(P/F)Fe-0.5C-2Cu steel,the hot compression tests were conducted at temperatures ranging from 900to 1 000 ℃ and strain rates from 0.1to 10s-1 using Gleeble-1500thermal simulator.The true stress-true strain curves at different temperatures and strain rates of P/F steel were obtained.It is found that dynamic recovery only occurs as strain rate is 10s-1 at 900℃,and the dynamic recrystallization is the main softening mechanism.The flow stress increases with decreasing temperature and increasing strain rate.The experimental data are employed to develop constitutive equations on the basis of the Arrheniustype equation by introducing the strain with nonlinear fitting.The flow stresses predicted by the proposed constitutive equations are in good agreement with the experimental values,and the correlation coefficient(R2)and the average absolute relative error(AARE)are 0.995 25and 3.07%respectively.These results indicate the proposed constitutive equations can effectively describe the hot deformation behavior of the material.  相似文献   

2.
 Modified CNS-Ⅱ F/M steel was designed for in-core components of supercritical water cooled reactor. Study on the hot deformation behavior of modified CNS-Ⅱ F/M steel is of great importance for processing parameter planning and microstructure controlling during hot deformation. The hot deformation behavior of modified CNS-Ⅱ F/M steel was investigated through isothermal hot compression test at temperature ranging from 1223 to 1373 K and strain rate 001 to 10 s-1. The true stress-true strain data gained from compression tests were used to built constitutive equation of modified CNS-Ⅱ F/M steel. The influence of strain on the accuracy of constitutive analysis was incorporated, assuming strain has a influence on material constants. A 5th order polynominal equation with very good accuracy was used to represent the influence of strain on material constant. The flow stresses calculated from the constitutive equation were compared with test values in the whole experiment range and the absolute average error for the constitutive equation in predicting flow stress is 4728%. At last, the recrystallization behavior of modified CNS-Ⅱ F/M steel was investigated. The relationship of critical strain and peak strain with Zener-Hollomon parameter were given by an experimental equation.  相似文献   

3.
Hot compression deformation behaviors of medium carbon Cr-Ni-Mo-Nb steel were investigated at deformation temperatures ranging from 1223 to 1423 Kand strain rates of 0.1,1and 5s-1.Dynamic recovery(DRV)and dynamic recrystallization(DRX)were observed during the hot compression deformation.For all of the samples,DRX occurred at deformation temperatures above 1323 Kat different strain rates,while below 1223 K,no DRX was observed.The activation energy of the tested steel was determined as 386.06kJ/mol.The ratio of critical stress to peak stress and the ratio of critical strain to peak strain were 0.835 and 0.37,respectively.Kinetic equations interpreting the DRX behavior of the tested steel were proposed,and the corresponding parameters including the volume fraction and the average grain size were determined.Moreover,the microstructures induced under different deformation conditions were analyzed.  相似文献   

4.
The 34CrMo4(AISI 4130)steel is extensively utilized in the compressed natural gas cylinders.Due to the importance of thermomechanical processing in the production of these cylinders,the dynamic recrystallization(DRX)characteristics of 34CrMo4 steel were investigated.The effect of hot deformation parameters such as temperature and strain rate on the dynamic restoration processes of a 34CrMo4 alloy was studied.Hot compression tests were performed in the temperature range of 900 to 1100 ℃ and the strain rate r...  相似文献   

5.
The static recrystallization behavior of SA508-III steel was investigated by isothermal double-hit hot compression tests at the deformation temperature of 950-1 250 ℃,the strain rate of 0. 01-1 s~(-1),and the inter-pass time of 1-300 s.The effects of deformation parameters,including forming temperature,strain rate,degree of deformation( pre-strain) and initial austenite grain size,on the softening kinetics were analyzed. Experimental results show that static recrystallization kinetics is strongly dependent on deformation temperature and degree of deformation,while less affected by the strain rate and initial grain size. The kinetics and microstructural evolution equations of static recrystallization for SA508-III steel were developed to predict the softening behavior and the statically recrystallized grain size,respectively. Based on the comparison between the experimental and predicted results,it is found that the established equations can give a reasonable estimate of the static softening behavior for SA508-III steel.  相似文献   

6.
 The static recrystallization kinetics of low-carbon steel cast strip was investigated by means of interrupted hot tensile tests. As-cast strip was reheated and soaked and its austenite grain size was similar to the width level of the as-cast columnar structure. The tests were carried out on Gleeble-3500 thermomechanical simulator. The deformation temperature is in the range of 800 to 1200 ℃ with strain rate of 001 to 1 s-1. The prestrain is fixed at 004 to 012, and the inter-hit delay time varies from 1 to 3000 s. Effect of deformation conditions and initial microstructure on static recrystallization behavior was investigated. The activation energy (Qsrx) and Avrami exponent (n) of static recrystallization were determined to have 241 kJ/mol and 054 respectively by linear regression of the experimental results. A kinetics model was proposed to describe the static recrystallization kinetics in low-carbon steel cast strip. The predicted softening fractions are in good agreement with the experimental results, indicating that the proposed equations can give an accurate estimate of the softening behaviors for the low-carbon steel cast strip.  相似文献   

7.
Susceptibility of the steel for further cold processing strongly depends on the whole prior history of deformation in the hot working regime.In the industrial hot working processes,e.g.at the roughing stage of hot rolling,or forging,material undergoes complex deformation modes that leads to gradients of both microstructure and properties across the deformed cross-section.Torsion and multiaxial compression tests with different amounts of strain reversals were conducted at elevated temperatures to study the effect of applied strain path on the phenomena occurring during microstructure evolution of Nb-microalloyed steels.Gathered results will provide data for the modification of existing constitutive equations that mostly do not account for the strain path changes.Better through-process modelling will then enable to achieve better properties and quality of the products for further cold processing.  相似文献   

8.
Hot Deformation Behavior of F6NM Stainless Steel   总被引:1,自引:0,他引:1  
The hot deformation behavior of F6NM stainless steel was investigated by hot compression test in a Gleeble-1500D thermal-mechanical simulator. The flow strain-stress curves were obtained and the corresponding metallographic observation of this steel under different deformation conditions was also carried out. This steel exhibi- ted dynamic recrystallization (DRX) in the temperature range of 1 273- 1473 K and the strain rate range of 0.01- 0.1 s^-1. The activation energy for hot deformation was determined to be 457.91 kJ/mol, and the hot deformation equations were also established. The flow instability zone was determined and could be divided into two regions. The first one was located in the temperature range of 1 173- 1 348 K and the strain rate range of 0. 056-10 s^-1 , while the second one is in the temperature range of 1398-1448 K and the strain rate range of 1.25-10 s^-1. In the end, the optimum conditions for hot working were provided.  相似文献   

9.
 Based on dislocation reaction theory and Avrami equation, a constitutive equation model was developed to describe dynamic recovery and dynamic recrystallization during hot deformation of T122 heat resistant steel, which have taken the effect of dynamic strain aging into account. Uniaxial hot compression test had been carried out over a wide range of strain rate (001 to 10 s-1) and temperature (900 to 1200 ℃) with the help of Gleeble 3500. Obtained experimental data was applied to determine the material parameters in proposed constitutive equations of T122 steel, by using the non-linear least square regress optimization method. The calculated constitutive equations are quantitatively in good agreement with experimentally measured curves and microstructure observation. It shows that propose constitutive equation T122 steel is able to be used to predict flow stress of T122 steel during hot deformation in austenite temperature scope.  相似文献   

10.
A hot compression experiment (1 073-1 473 K,strain rates of 0.001-10 s-1 )of SA508GR.4N low alloy steel was performed using a Gleeble-3800 thermal-mechanical simulator,and the hot deformation behavior of the steel was investigated by analyzing both the true stress-true strain curves and its microstructures.The thermal de-formation equation and hot deformation activation energy (Q)of SA508GR.4N steel were obtained by regression with a classic hyperbolic sine function.The hot processing map of SA508GR.4N steel was also established.An em-pirical equation for the stress peak was described for practical applications.The SA508GR.4N steel showed a critical Zener-Hollomon parameter (lnZc)for dynamic recrystallization (DRX)of 37.44,below which full DRX may occur. The sensitivity of the SA508GR.4N steel increased linearly with test temperature,such that higher temperatures led to enhanced workability.  相似文献   

11.
采用Gleeble-3800热模拟试验机进行了DIN 1.2738塑料模具钢(/%:0.35~0.46C,0.20-0.40Si,1.30~1.60Mn,1.80~2.20Cr,0.90~1.20Ni,0.15~0.23Mo)的热压缩实验,获得了该钢在850~1250℃、应变速率在0.01~30的应力-应变曲线。基于得到的热变形数据,建立了该钢的峰值应力以及应变补偿的热变形本构方程和热加工图,并结合热加工图的结果分析了该钢合理的热加工参数范围。结果表明,DIN 1.2738钢的热变激活能为354.21 kJ/mol,利用建立的应变补偿的双曲正弦本构方程可对塑料模具钢的热变形曲线进行准确预测,通过加工图的分析可得DIN 1.2738塑料模具钢的最佳的热变形工艺参数范围为:(1)温度950~1 150℃,应变速率0.01~0.7 s-1;(2)温度1170~1200℃,应变速率0.01~1 s-1。  相似文献   

12.
运用Gleeble-3800热模拟试验机研究了1Cr17Ni1马氏体-铁素体双相不锈钢在变形温度为950~1150℃、应变速率为0.1~10 s-1条件下的热压缩变形行为。运用双曲正弦函数构建了本构方程,得到了表观激活能为391.586 kJ/mol,并基于动态材料模型绘制了1Cr17Ni1钢不同应变量下的热加工图。观察变形后的组织形貌得到较低温度下发生动态回复与动态再结晶,较高温度只发生动态回复,综合热加工图与变形后组织得到最佳热变形工艺:热加工温度范围为950~1000℃、热加工变形速率范围为0.1~0.3和5~10 s-1。  相似文献   

13.
Thermal fatigue test has been carried out on widely used hot work steel 4Cr5MoSiVl and a low alloyed steel 3Cr3MoV in temperature range of 200 to 700 °C. Tempering resistance, as well as high temperature hardness/strength of steel specimens, works as a dominating material parameter on thermal fatigue resistance. During the heating period, high hardness can depress the inelastic deformation. This deformation is the origination of tensile stress, which acts as the driving force of heat checking during the cooling period. The cyclic strain-oxidation interaction can speed up the damage on surface defects, which plays an obvious role in initiation of thermal cracks. On 4Cr5MoSiVl steel specimens, borders between the matrix and inclusions such as titanium compounds, or lager carbides such as primary carbides, are focused by strain and attacked by oxidation, and are main initiating places of cracks. While on 3Cr3MoV steel specimens, larger strain causes plastic deformation concentrating around grain boundaries. Then the following oxidation accelerates this grain boundary damage and creates cracks.  相似文献   

14.
Herein, high-temperature hot compression tests are carried out to investigate the hot deformation behavior of a novel Cr–Mo–V hot work die steel. Meanwhile, a strain compensation Arrhenius constitutive equation is created, and the fitting correlation coefficient R between the experimental and predicted values is 0.98921, with a mean average absolute relative error (AARE) of 3.82%. According to the results, the hot deformation constitutive equation of the novel Cr–Mo–V steel can predict the flow stress of hot deformation with high accuracy. Furthermore, the equations for critical stress (strain), peak stress (strain), and Zener–Holomon parameters are constructed, and they demonstrate a satisfactory linear fit. Additionally, a hot processing map of the novel Cr–Mo–V steel is developed at strains of 0.4, 0.5, 0.6, and 0.7. By analyzing the hot processing map and viewing the microstructure, this study concludes that the optimal hot processing parameters of the novel Cr–Mo–V steel are 1050–1150 °C and 0.8–1 s−1 at a strain of 0.7, with a peak power dissipation efficiency of nearly 0.68.  相似文献   

15.
曾莉  张威  王琦  朱丽丽 《钢铁》2017,52(10)
为了研究超级奥氏体不锈钢Cr20Ni24Mo6N钢的高温变形行为,采用Gleeble热模拟试验机进行了等温压缩试验,建立了合金的热加工图。结果表明,当变形温度为1 000~1 200℃时,Cr20Ni24Mo6N钢的流变曲线表现出典型的"加工硬化+动态再结晶软化"特点;Cr20Ni24Mo6N钢的热激活能Q为678.656 kJ/mol。通过加工图与微观组织综合分析得出,超级奥氏体不锈钢Cr20Ni24Mo6N的合适热加工工艺为,应变速率为10 s~(-1)左右,应变量为0.5~0.8,变形温度为1 150~1 200℃。  相似文献   

16.
The hot deformation behavior of as-cast AISI M2high-speed steel containing mischmetal(RE)has been investigated on a Gleeble-3500simulator in the temperature range of 1 000-1 150℃and strain rate range of 0.01-10 s-1 at true strain of 1.0.The mechanical behavior has been characterized using stress-strain curve analysis,kinetic analysis,processing maps,etc.Metallographic investigation was performed to evaluate the mechanism of flow instability.The results show that the deformation activation energy decreases with increasing deformation temperature; the efficiency of power dissipation increases with decreasing strain rate and increasing temperature;flow instability is observed at low-to-medium temperature and higher strain rate region when the strain is smaller,but extends to lower strain rate and high temperature regions with the increment of strain,in which it is manifested as flow localization near the grain boundary.Hot deformation equations and processing maps are obtained.The optimal processing window is suggested and the deformation mechanism is dynamic recrystallization(DRX).  相似文献   

17.
为了获得C HRA 5钢轧制生产的最佳工艺参数,采用Gleeble 3800热力模拟试验机对C HRA 5钢进行了双道次热压缩实验。实验在变形温度范围为900~1100℃,应变速率范围为001~1s-1,道次间隙时间分别为1、5、15、30s的条件下获得C-HRA -5钢的真应力 应变曲线。采用0.2%补偿法计算得到了软化分数,且软化分数随变形温度的升高和应变速率的增大而增加。通过线性回归分析得到了MDRX的动力学方程。建立的C-HRA-5钢热加工图表明材料在1000~1100℃的范围内变形稳定。此外,道次间隙时间为5s时,C-HRA-5钢在较低温度下进行第2道次压缩的过程中不会出现失稳。  相似文献   

18.
王天翔  胡尚举 《特殊钢》2019,40(6):7-11
在Gleeble-3500热模拟试验机上进行高温压缩实验,研究00Cr26Mo4超级铁素体不锈钢在变形温度为1050~1250℃、应变速率为0.01~10 S-1条件下的热变形行为。采用幂函数、指数函数和双曲正弦模型模拟该材料的热变形参数,建立了相应的热变形本构方程。结果表明,在热压缩过程中,流变应力随变形温度的升高而降低,随应变速率的升高而增加,流变应力并未出现明显峰值,材料的软化机制仅有动态回复。探究了幂函数、指数函数和双曲线函数3种模型与00Cr26Mo4钢本构关系的相关性。结果表明,双曲正弦函数模型更符合00Cr26Mo4超级铁素体不锈钢热加工流变应力应变曲线变化规律,并基于双曲正弦函数模型建立了00Cr26Mo4钢的本构方程,计算了热变形激活能238.836 kJ/mol。  相似文献   

19.
The contamination of 30Cr2Ni4MoV rotor steel with exogenous nonmetallic inclusions is studied. Technological measures intended to decrease the level of contamination of the steel with nonmetallic inclusions and to enhance its quality are recommended.  相似文献   

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