热处理工艺对38CrMoAlA钢组织与性能的影响

 通过热处理工艺试验研究了38CrMoAlA钢不同淬火温度、冷却方式和回火温度对38CrMoAlA钢微观组织及力学性能的影响。结果表明,在900—1000℃淬火温度范围内,淬火温度对该钢的力学性能影响不大。不同的冷却方式因淬火介质的冷却强度不同,导致淬火后的组织不同,从而影响该钢的力学性能。回火温度对该钢的力学性能的影响较为显著,100—400℃范围内回火表现出回火脆性,在620℃回火能得到较好的强韧配合。该钢采用940℃,1h,油冷620℃,5h,油冷的热处理工艺时,可获得适宜的力学性能。     

热处理工艺对NM600耐磨钢板组织性能的影响

为了提高NM600耐磨钢应用于恶劣工况下的耐磨性能,通过正交试验研究各热处理参数,包括淬火温度、淬火保温时间、回火温度、回火保温时间等,对于试验钢组织性能的影响。结果表明,回火温度是抗拉强度、屈服强度、冲击功、布氏硬度最主要的影响因素。随着回火温度升高,伸长率先小幅上升再缓慢下降,抗拉强度、屈服强度、冲击功和布氏硬度均呈下降趋势。试验钢热处理后的微观组织主要是板条马氏体、还有少量的残余奥氏体和碳化物。确定了最佳热处理工艺为:在860℃淬火保温30 min,200℃回火保温60 min。所获得的最优工艺性能为:抗拉强度1 956.2 MPa、屈服强度1 566.7 MPa、伸长率12.7%、-20℃冲击功19.2 J、布氏硬度576.5 HB。     

深冷及回火处理对高速钢M42组织和力学性能影响

采用金相显微镜、扫描电镜及硬度仪,研究了-196℃深冷处理与常规热处理工艺组合对M42高速钢微观组织及硬度的影响,所采用的组合工艺包括:淬火+深冷处理,淬火+深冷处理+回火,淬火+回火+深冷处理.结果表明:淬火后深冷处理24h的工艺能明显细化晶粒,提高M42高速钢的硬度,促进残余奥氏体向马氏体转变及碳化物析出并弥散分布,并改变了马氏体的形态.在回火前对M42钢进行深冷处理可降低二次硬化回火温度,峰值温度由525℃降至450℃,硬度值为998.2HV,较未深冷处理提高了5.0%.回火后深冷处理工艺对M42高速钢组织及硬度的影响不明显.     

45钢亚温淬火组织及性能研究

45钢是我国目前用量较大的调质钢,通过研究45钢经调质和亚温淬火热处理后的硬度,冲击韧度和金相组织,来寻求合适的45钢热处理工艺.结果表明,45钢仅采用调质处理,不能满足高硬度高韧性的技术要求,采用亚温淬火热处理配合可解决上述问题,得到最优的综合力学性能,考虑经济性时可直接采用770℃淬火500℃回火的热处理工艺.在保证45钢强度和硬度的同时,要提高韧性的最理想的热处理工艺为840℃淬火550℃回火＋770℃淬火500℃回火.     

Cr12MoV钢拉深凹模热处理工艺的改进

某公司采用拉深凹模生产汽车车门内板,其材料为Cr12MoV钢,热处理工艺为1030℃淬火和220℃回火,在使用过程中拉深凹模容易开裂。为此,采用金相分析和性能测试的方法,分析Cr12MoV钢拉深凹模的热处理工艺,测定不同温度淬火和回火后的硬度和冲击韧性,最终确定出满足性能要求的最佳淬火与回火温度。结果表明,Cr12MoV钢经1030℃淬火与220℃回火后韧性低,导致拉深凹模开裂。而在980℃淬火和240℃回火处理,可以获得较高的硬度以及良好的韧性。建议该公司对拉深凹模采用980℃淬火和240℃回火处理,减少其开裂,延长其使用寿命。     

不同热处理工艺下H13钢组织性能的变化

文章通过热处理工艺参数的变化研究了H13钢组织结构及力学性能的变化规律.试验结果表明,H13钢经过1050℃淬火、600℃2次回火后获得良好的力学性能,伸长率达到7.55%左右,抗拉强度达到1340 MPa;淬火温度高于1080℃后,奥氏体晶粒明显长大,淬火冷却后晶粒不均匀;回火次数2次最佳.     

提高3Gr_2W_8V钢压铸模寿命的热处理工艺

在对3Gr_2W_8V 钢铝合金压铸模失效分析的基础上,测定了不同热处理工艺下硬度,断裂韧性 K_(1c)和冲击韧性α_k,认为 K_(1c)值低是模具开裂失效的主要原因。试验结果表明,提高淬火加热温度可使该钢的回火稳定性,回火后硬度,二次硬化效应,断裂韧性得到改善和提高。指出了能够提高3Gr_2W_8V 钢压铸模寿命的新工艺为:调质处理后于1220℃高温加热淬火,650℃回火二次。     

热处理工艺对27SiMn钢力学性能的影响

27SiMn液压支架管经过调质热处理来实现其良好的综合力学性能.采用四因素三水平的热处理正交试验,研究了不同热处理工艺参数(淬火温度、淬火保温时间、回火温度和回火保温时间)对力学性能的影响,并确定了最优热处理工艺制度为930℃,40 min淬火和480℃,50 min回火.经最优热处理工艺处理后,其力学性能为:屈服强度895 MPa,抗拉强度1030MPa,伸长率15%,断面收缩率54%,冲击功53.3 J,满足了GB/T 17396—1998标准中对27SiMn钢的性能要求.     

热轧态H13钢调质工艺参数模拟计算与实验验证

利用JMatPro软件,模拟计算得到热轧态H13钢平衡相组成、奥氏体连续加热转变(continuous heating transformation diagram of austenite,TTA)曲线图、过冷奥氏体连续冷却转变(continuous cooling transformation diagram,CCT)曲线图、淬透性曲线、碳化物和相转变曲线；结合性能要求,确定H13钢的调质工艺参数范围,并进行实验验证。实验结果表明:H13钢经1 050 ℃淬火后得到的最高硬度为53.4洛氏硬度(Rockwell Hardness C,HRC),50 mm处仍保持45 HRC以上的较高硬度；H13钢随着冷速的提升强度和硬度略有升高；现企业选用的工艺参数(1 050 ℃+45 min淬火,630 ℃+100 min回火)可行。     

淬火后回火温度对50Mn钢力学性能的影响

50Mn中碳钢属优质碳素结构钢,常用于石油套管接手、轴齿轮、齿轮、摩擦盘、花键轴等,其热处理工艺通常是淬火回火[1].不同温度回火将影响钢的金相组织,使钢得到不同的强度、塑性和韧性的配合.本研究选择880℃淬火后300、400、500、600、670 ℃等不同温度回火,分别进行拉伸、冲击和韧断试验,探讨不同回火温度对50Mn钢力学性能的影响.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that