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本文对两种不同预备热处理的17CrNiMo6钢试样,进行了渗碳淬火工艺试验,采用金相法对渗层的组织和性能进行了检验分析。结论是:调质预备热处理的碳化物级别比正回火的有明显的改善,调质预备热处理对马氏体、残余奥氏体、内氧化的级别比正回火的也有不同程度的改善。总之,采用调质预备热处理对改善渗碳层的性能有优势。 相似文献
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本文对18CrNiMo7-6渗碳钢进行了不同热处理工艺试验,预备热处理采用调质、正回火工艺,渗碳后采用一次淬火、二次淬火工艺进行对比。采用金相法检验预备热处理后的金相组织、渗碳后的心部组织,和碳化物级别、马氏体、残余奥氏体、内氧化的评级等;同时对预备热处理后材料的力学性能进行了检验。结果表明:采用调质预备热处理、渗碳后二次淬火工艺的18CrNiMo7-6渗碳钢的渗碳层性能指标最好,适用于高参数齿轮渗碳淬火。 相似文献
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对12Cr2Ni4钢进行渗碳淬火工艺试验,研究了预备热处理、渗碳保温时间、渗碳后淬火方式对12Cr2Ni4钢内氧化级别的影响。采用金相法检验表层内氧化层的深度,并按照国家标准对内氧化评级。结果表明:预备热处理采用调质的抗内氧化能力是明显好于正回火的;一次淬火的抗内氧化能力明显好于二次淬火的;随着渗碳保温时间的延长,表层内氧化层的深度增加。因此,预备热处理后采用调质、渗碳后采用一次淬火、渗碳保温时间缩短可以明显减小表层内氧化的层深。 相似文献
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用气体渗氮+淬火(N+Q)复合处理技术对GCr15进行表面强化,并与单纯的气体渗氮、淬火进行比较,系统研究了硬化层的物相、组织结构及干摩擦特性。结果表明:530℃气体渗氮9 h后,渗氮层的化合物层为ε相,厚度约为40μm;而渗氮之后淬火(N+Q)复合处理使氮化物完全分解,促使N元素向基体扩散,扩散区深约900μm,N固溶强化作用使得扩散区硬度比淬火硬度约高200 HV0.1,但是因氮化物分解产生孔隙致使表层硬度下降。分别在20 N和100 N载荷进行往复干摩擦试验,气体渗氮与N+Q复合处理都能有效降低摩擦因数。在20 N载荷时,N+Q复合处理试样体积磨损率低于渗氮与淬火试样;而在100 N载荷时,因其表面孔隙,使得初始磨损比淬火试样严重,但是磨损一段时间后耐磨性能提高。 相似文献
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9SiCr钢渗氮淬火复合热处理 总被引:3,自引:2,他引:1
渗氛淬火能使钢获得比单一渗氮或单一淬火更高的硬度、耐磨性和力学性能,具有广阔的应用前景。1试验材料和方法试验明9SiCr钢。硬度试样尺寸为φ15×10mm。热处理设备有IOOkW盐治炉、25kw低温回火炉、DS型低温箱和I,D-60kw离子渗氮炉。热处理工艺如表1所示。表面硬化区硬度用HVA-IOA型小负荷维氏硬度计测试,从表面起每磨去0.lmrn测量一次维氏硬度值。基体硬度用HRC-15OA洛氏硬度计测试。2试验结果门)淬火个冷处理上回火与淬火一回火后硬度比较gsiCr钢淬火十冷处理硬度同后淬火后再经150、18O和2()OC回火后的硬度比较,… 相似文献
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金相法与硬度法测量离子渗氮层深度差异性研究 总被引:2,自引:1,他引:1
用金相法与硬度法对不同调质硬度的42CrMo、38CrMoAl钢试样离子渗氮层厚度进行测量和比较.试验结果表明,42CrMo和38CrMoAl钢的调质硬度对硬度法测层深有较大影响,对金相法则影响不大,使二者得到的结果不能很好的统一.当调质硬度低于29 HRC时,硬度法测得的渗氮层厚度大于金相法测得的渗氮层厚度;当调质硬度升高到29~31 HRC时,两种测试手段得到的结果基本一致;当试样调质硬度高于32 HRC时,金相法测得的结果大于硬度法测得的结果.调质硬度越高,二者之间的差别越大.当两种测试手段存在差别时,渗氮层越厚,二者测得的结果差值也越大. 相似文献
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压力铸造用的压铸模和热变形模具在渗氮前须进行预先热处理—正火,调质。一些文献资料,例如资料〔1、2〕,关于预先热处理对渗氮过程和渗氮钢机械性能之影响的介绍是相矛盾的。因此,本文研究了预先热处理热循环处理对40X,Y8,3X2W8等结构钢和工具钢(见表1)的心部性能及渗氮层的影响。为了比较,将所研究钢的试样在渗氮前进行了正火和调质处理。其预先热处理规范和渗氮结果见表2。拉伸试验采用直径10mm,标距长度L=50mm的圆形试样。冲击韧性试验用I型V形缺口试样。在布氏和洛氏硬度计上测定硬度。渗氮层的显微硬度在IIMT—3型设 相似文献
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Deng-Kui Zhang Guo-Qing Wang Ai-Ping Wu Ji-Guo Shan Yue Zhao Tian-Yi Zhao Dan-Yang Meng Jian-Ling Song Zhong-Ping Zhang 《金属学报(英文版)》2019,32(6):684-694
In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone. 相似文献
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After nearly two years'tense construction the first phase of industrialized base of Shenyang Research Institute of Foundry 《中国铸造》2008,5(1):63-64
After nearly two years' tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry (SRIF), located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation. 相似文献
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Z. Sun S.L. Zheng Y. Zhang 《金属学报(英文版)》2007,20(3):187-192
Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process. 相似文献
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R. González-Martínez 《金属学报(英文版)》2007,20(4):235-240
The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke. 相似文献
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The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C). 相似文献
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The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel. 相似文献
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B.W. Zhang B.W. Li 《金属学报(英文版)》2007,20(2):129-138
On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes' collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process. 相似文献
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R.Z. Wu Z.K. Qu B.D. Sun D. Shu J. Wang 《金属学报(英文版)》2007,20(3):193-198
The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results. 相似文献
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This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before. 相似文献
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Chao Yang He-Fei Huang Massey de los Reyes Long Yan Xing-Tai Zhou Tian Xia De-Liang Zhang 《金属学报(英文版)》2015,28(7):809
Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties. 相似文献