Ti3Al-Nb合金超塑压缩变形的研究

研究了Ｔｉ－２４Ａｌ－１４Ｎｂ－３Ｖ－０．５Ｍｏ合金压缩时的超塑变形行为和变形过程中的组织变化。结果表明：所研究合金在ｔ＝９８０℃、ε＝７．２×１０－３ｓ－１的条件下ｍ值为０．３４,压缩时的真应变可大于１．６。在合金的超塑变形初期,Ｏ相发生动态再结晶和等轴化过程。随着变形过程的进行,新形成的Ｏ相晶粒在Ｂ２相中滑动和转动,Ｂ２相中的位错运动和界面扩散起调节作用     

34CrNi3Mo钢高温变形行为的研究

利用Ｆｏｒｍａｓｔｏｒ－Ｐｒｅｓｓ热模拟试验机，研究了３４ＣｒＮｉ３Ｍｏ合金结构钢在温度８４０～１２００℃变形速度０．１～８０ｓ＾－１的变形条件下的热压缩行为，获得了３４ＣｒＮｉ３Ｍｏ钢在热变形时发生动态再结晶的临界条件（包括临界因子Ｚ１和临界应变ε）及再结晶粒大小Ｄｄｙｎ与Ｚｅｎｅｒ－Ｈｏｌｌｏｍｏｎ因子Ｚ，奥氏体起始晶粒尺寸Ｄ０和应变ε之间的关系，并给出了回归公式。     

34CrNi3Mo钢的高温变形行为

利用Ｆｏｒｍａｓｔｏｒ－Ｐｒｅｓｓ热模拟试验机，研究了３４ＣｒＮｉ３Ｍｏ合金结构钢在温度８４０￣１２００℃，变形速度０．１￣８０ｓ＾－１的变形条件下的热压缩行为。获得了３４ＣｒＮｉ３Ｍｏ钢在热变形时发生动态再结晶的临界条件（包括临界因子Ｚｃ和临界应变εｃ）及再结晶晶粒大小Ｄｄｙｎ与Ｚｅｎｅｒ－Ｈｏｌｌｏｍｏｎ因子Ｚ、奥氏体起始晶粒尺寸Ｄ０和应变ε之间的关系，并给出了回归公式。     

应用ProcessingMap研究D2钢高温变形的动态应变时效

应用以动态材料模型为基础的ＰｒｏｃｅｓｓｉｎｇＭａｐ研究了Ｄ２钢在变形温度９００～１１６０℃、变形速率０．０１～１０．００ｓ－１区间的动态应变时效规律。结果表明，Ｄ２钢在变形温度为１１２０～１１５０℃、变形速率为０．０１ｓ－１条件下发生动态应变时效，并表现出强烈的硬化效应。同时，应变速率敏感系数小于零可以作为发生动态应变时效的一个标志。     

铁素体—珠光体钢组织和性能关系

本文对含０．０６５％￣０．２２％Ｃ、０．００２￣０．０２１％Ｓ、０．６￣１．５％Ｍｎ、０．０２￣０．４％Ｓｉ（重量百分数）系列钢（普通Ｃ－Ｍｎ、Ｃ－Ｍｎ－Ａｌ、Ｃ－Ｍｎ－Ｎｂ－Ａｌ钢）进行了研究，大多数此类钢经常化处理，以８００￣４００℃的平均冷却速率在４０￣０．８Ｋｍｉｎ＾－１变化。这相当于１２￣５００ｍｍ厚板在空气中冷却的速率。一些高温奥氏体化处理随后炉冷的钢产生粗铁素体晶粒和粗晶界碳化物。得     

低碳贝氏体钢的摩擦焊接性

试验研究了低碳贝菌体钢０．１７℃－１，１．７２Ｍｎ－１。１２Ｃｒ－０．５２Ｍｏ的焊接工艺参数及热处理对组织和性能的影响。结果表明，摩擦变形量为１．０ｍｍ，焊接接头采用９１０℃正火。３５０℃回火，可得到良好的组织和性能。     

18Mn—18Cr—0.5N奥氏体钢热变形行为

用热扭转试验及定量金相法研究了１８Ｍｎ－１８Ｃｒ－０．５Ｎ钢热变形条件下的力学行为和动态组织变化。获得了１８Ｍｎ－１８Ｃｒ－０．５Ｎ钢的形变激活能及峰值应力，峰值应变和动态再结晶晶粒尺寸与Ｚｅｎｅｒ－Ｈｏｌｌｏｍｏｎ参数Ｚ之间的关系式。研究了变形温度和应变速率对１８Ｍｎ－１８Ｃｒ－０．５Ｎ钢热加工延性的影响。     

喷射沉积快速凝固Al—Li合金的时效析出相

采用新型的喷射沉积技术制备了Ａｌ－３．８Ｌｉ－０．８Ｍｇ－０．４Ｃｕ－０．１３Ｚｒ（Ｎｏ．１）和Ａｌ－２．１５Ｌｉ－１．２８Ｃｕ－１．２６Ｍｇ－０．１Ｚｒ（Ｎｏ．２）合金，对合金在时效过程中的析出相进行了比较和分析，实验结果表明，喷射沉积快速凝固Ａｌ－Ｌｉ合金的δ相粒子与铸锭冶金法Ａｌ－Ｌｉ合金的δ粒子有较大差异，高Ｌｉ低Ｃｕ含量的Ｎｏ．１合金δ相的体积分数明显高于低Ｌｉ高Ｃｕ含量的Ｎｏ．２合金，     

冷作模具钢D2钢高温变形行为的研究

利用ＧＬＥＥＢＬＥ－１５００热力模拟机，对Ｄ２钢的高温变形行为进行实验研究，结果表明：Ｄ２钢在变形温度为９００￣１１６０℃、变形速率为０．０１￣１０ｓ＾－１的区间变形时，发生动态再结晶、动态应变时效、脆性穿晶断裂以及热裂等过程，并分析了其原因。在此基础上对Ｄ２钢的高温变形工艺制度进行了优化，以指导生产实践。     

18Mn－18Cr－0．5N奥氏体钢热变形行为

用热扭转试验及定量金相法研究了１８Ｍｎ－１８Ｃｒ－０．５Ｎ钢热变形条件下的力学行为和动态组织变化。获得了１８Ｍｎ－１８Ｃｒ－０．５Ｎ钢的形变激活能及峰值应力（σ＿ｐ），峰值应变（ε＿ｐ）和动态再结晶晶粒尺寸（ｄ）与Ｚｅｎｅｔ－Ｈｏｌｌｏｍｏｎ参数Ｚ之间的关系式。研究了变形温度和应变速率对１８Ｍｎ－１８Ｃｒ－０．５Ｎ钢热加工延性的影响。     

The thermal expansion of grain boundaries

The thermal expansion öf grain boundaries in copper was measured by a newly developed method comparing the thermal expansion of copper polycrystals (same chemical composition) with small (17 μm) and large (19 mm) grain sizes. From these measurements, the thermal expansion coefficient of a grain boundary in copper was deduced to be 40 to 80·10⁻⁶K⁻¹ which is about 2.5 to 5 times the expansion coefficient of a copper crystal suggesting large anharmonic atomic vibrations in grain boundaries. The thermal expansion of grain boundaries (which was not measurable so far) may be used to test structural models of interfaces.     

F40MnV非调质钢的热变形行为

 采用Gleeble 1500热模拟实验机对F40MnV非调质钢在温度为1 223~1 473 K,应变速率为01~10 s-1的热变形行为进行研究。通过奥氏体再结晶动力学回归计算得到了F40MnV钢的变形激活能,峰值应力和峰值应变与Zener Hollomon参数的关系表达式。同时,得到了F40MnV钢的动态再结晶动力学方程和动态再结晶晶粒尺寸的数学模型。     

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The effect of deformation parameters on hot deformation of superalloy 800H was studied by means of single-pass compression test. It was found that smaller initial grain size, higher deformation temperature and lower strain rate are more easily to cause dynamic recrystallization. And when dynamic recrystallization can take place during deformation, the fraction of dynamic recrystallization increases with increasing of strain. The models of dynamic recrystallization activation energy, critical strain, dynamic recrystallization kinetics, dynamic recrystallization kinematics and grain size of dynamic recrystallization for 800H were obtained through the analysis of data obtained by single-pass compression. The variation tendency for grain size simulated by Deform-2D is consistent with metallographic statistics, and the average error is 4. 5??m. Very small average error shows that the model is consistent with practical situation and can be used to predict recrystallized grain size for 800H during thermal deformation.     

分步冷却过程中磷的非平衡晶界偏聚

研究了分步冷却过程中12Cr1MoV钢磷的非平衡晶界偏聚。从理论上计算了磷的晶界偏聚等效时间和晶界偏聚量，并用实验验证了根据动力学计算得出的磷的晶界偏聚浓度。试验结果与理论计算值相符．可为预测钢在实际服役状况下的晶界脆性提供依据。     

Isolation of carbon and grain boundary carbide effects on the creep and intergranular stress corrosion cracking behavior of Ni-16Cr-9Fe-xC alloys in 360 °C primary water

The influence of carbon and grain boundary carbides on intergranular stress corrosion cracking (IGSCC) of controlled-purity Ni-16Cr-9Fe-xC alloys in 360 °C primary water was investigated using constant load tensile (CLT) and constant extension rate tensile (CERT) tests. The CLT test results confirmed that carbon in solution decreases the creep rate by several orders of magnitude, while grain boundary carbides serve to increase the creep susceptibility. Although carbon increases the work hardening rate, it is demonstrated, using the Bailey-Orowan creep model, that the primary effect of carbon in solution is to delay the recovery process of climb at the grain boundary, thereby reducing the creep rate. Grain boundary carbides produce a negligible contribution to the internal stress and may increase the creep rate by acting as dislocation sources. Grain boundary carbide precipitation increases IGSCC resistance in 360 °C primary water containing 0, 1, and 18 bar hydrogen, providing the highest overall resistance to both environmentally induced creep and cracking. The magnitude of the beneficial effect of grain boundary carbides is extremely sensitive to hydrogen overpressure, with the largest influence observed for 1 bar hydrogen. The detrimental effect of hydrogen on IGSCC shows consistencies with aspects of both film rupture/slip dissolution and hydrogen embrittlement models.     

加热工艺对Nb-Ti微合金钢奥氏体晶粒长大的影响

 为了解加热制度对Nb Ti微合金钢的奥氏体晶粒长大和析出行为的影响,采用OM、TEM和EDS分析技术,研究了Nb Ti微合金钢在不同加热温度和保温时间的奥氏体晶粒长大行为,以及微合金元素碳氮化物析出行为。结果表明,随加热温度升高,奥氏体晶粒尺寸逐渐长大,当加热温度超过1 200 ℃时奥氏体晶粒尺寸快速长大。随保温时间延长,奥氏体晶粒尺寸逐渐长大,当保温时间超过2.0 h时奥氏体晶粒尺寸快速长大。EDS分析显示Nb Ti钢中的析出物为(Nb,Ti)(C,N)复合相,随着加热温度升高和保温时间延长,析出相体积分数减少,尺寸增大,从而减弱对奥氏体晶粒的细化作用;Nb Ti微合金试验钢合适的加热温度范围为1 150～1 200 ℃,保温时间低于2.0 h。     

新型高效环保黄铜细化剂对铅黄铜锭组织和性能的影响

研究了AZ-1新型黄铜细化剂的晶粒细化作用，与稀土细化剂的晶粒细化效果进行了比较；分别对用AZ-1新型细化剂和稀土细化剂细化处理的铅黄铜锭进行了组织和性能的对比研究。生产试验结果表明，AZ-1新型细化剂具有显著的晶粒和相细化作用，其细化能力明显优于稀土细化剂；与稀土细化剂细化处理的铅黄铜锭相比，用AZ-1新型细化剂制备的铅黄铜锭的显微组织及铜液流动性较好。     

大型盾构机用轴承钢奥氏体晶粒长大模型

 利用箱式电阻炉研究了加热温度为900,950,1 000,1 050,1 100,1 150 ℃,保温时间为10,30,60,90 min时大型盾构机用GCr15SiMn轴承钢的奥氏体晶粒长大规律,利用截线法统计奥氏体晶粒尺寸。试验结果表明,随着加热温度提高和保温时间延长,奥氏体晶粒尺寸和长大速率逐渐增大,加热温度的提高比保温时间的延长对奥氏体晶粒长大速率影响更大,奥氏体晶粒迅速长大的加热温度为1 000 ℃,保温时间为60 min。在已有晶粒长大模型的基础上,通过对试验数据进行线性回归,得到了描述GCr15SiMn钢奥氏体晶粒长大规律的数学模型。     

Dynamic Recrystallization of Hot Deformed 3Cr2NiMnMo Steel: Modeling and Numerical Simulation

Hot compression tests of 3Cr2NiMnMo steel were performed at temperatures in the range of 850 to 1100 °C and with strain rates of 10^?2s^?1 to 1s^?1. Both the constitutive equations and the hot deformation activation energy were derived from the correlativity of flow stress, strain rate and temperature. The mathematical models of the dynamic recrystallization of 3Cr2NiMnMo steel, which include the dynamic recrystallization kinetics model and the crystallization grain size model, are based on Avrami's law and the results of thermosimulation experiments. By integrating derived dynamic recrystallization models with the thermal-mechanical coupled finite element method, the microstructure evolution in hot compressive deformation was simulated. The distribution of dynamic recrystallization grains and grain sizes were determined through a comparison of the simulation results with the experimental results. The distribution of strain and dynamic recrystallization grain is also discussed. The similarity between the experimental results and the simulated results indicates that the derived dynamic recrystallization models can be applied effectively to predict and analyze the microstructure evolution in hot deformed 3Cr2NiMnMo steel.     

Three-dimensional Numerical Simulation and Experimental Analysis of Austenite Grain Growth Behavior in Hot Forging Processes of 300M Steel Large Components

The microstructure models were integrated into finite element (FE)code,and a three-dimensional (3D) FE analysis on the entire hot forging processes of 300M steel large components was performed to predict the distri-butions of effective strain,temperature field and austenite grain size.The simulated results show that the finest grains distribute in the maximum effective strain region because large strain induces the occurrence of dynamic re-crystallization.However,coarse macro-grains appear in the minimum effective strain region.Then,300M steel forg-ing test was performed to validate the results of FE simulation,and microstructure observations and quantitative analysis were implemented.The average relative difference between the calculated and experimental austenite grain size is 7.5 6%,implying that the present microstructure models are reasonable and can be used to analyze the hot forging processes of 300M steel.