关于热锻模油冷时间的计算

<正> 目前热锻模的材料一般都是5CrNiMo和5CrMnMo。 热处理工艺都是加热到淬火温度,经过保温后出炉,在空气中予冷到780℃左右淬油,在油中冷却到150°～260℃出油并及时回火。     

连续冷却条件下Ti-1300合金的组织演变与连续转变图

通过OM、SEM、TEM和EBSD研究了Ti-1300合金在连续冷却条件下组织演变规律和亚稳β相的分解形式,并采用高精度膨胀法建立了合金的连续冷却转变动力曲线。结果表明：当连续冷却速度比较缓慢时,Ti-1300合金发生β → α + β转变,并获得集束状的显微组织;而当冷却速度0.3 °C/s ＜v＜ 1.5 °C/s时,Ti-1300合金发生β → α + β + β_m,并获得细针状的α + β组织和残余的β_m相;当冷却速度大于3 °C/s时,Ti-1300合金基本获得全部β相,所以把3 °C/s认为是合金的临界冷却转变速度。在缓慢冷却过程中,Mo当量梯度是合金中α相生长主要动力。随着冷却速度的增加,Ti-1300合金的显微硬度先增加后降低,在冷却速度为0.3 °C/s时,显微硬度达到最大值。     

电加热快速热循环注塑模具热响应分析研究

研究了电加热快速热循环注塑工艺原理和模具结构,构建了电加热注塑模具的二维和三维热响应分析模型,分析获得了加热过程和冷却过程中模具型腔表面的热响应规律和温度分布规律,探讨了模具结构、加热元件和模具材料等因素对模具热响应效率和温度均匀性的影响。加热阶段,模具型腔表面的平均升温速率可达3．3℃／s,经过70S加热,模具表面可升高至250℃左右;冷却阶段,熔体的平均降温速率约为3．6℃／s。     

注射模油加热温控的讨论

<正> 一、引言 为了使注射模具有一定的温度,有加热和冷却两种办法。当模温要求100℃以上时,采用油加热有许多优点,国外已广泛应用。 二、确定加热所需的功率 为了计算加热所需的功率,应对模具的热平衡进行计算。热平衡图如图1所示。     

单面锪孔跳步模设计

<正> 在板料上冲孔后需锪沉孔或埋头沉孔时一般用金属切削一占削方法加工,目前有一种新的工艺办法来代替锪孔,可以提高产品质量和劳动生产率。 本文主要介绍单面锪孔跳步模设计原理及计算方法。模具冲制A_3材料,料厚t:4mm。如图1所示零件在二孔φ4.5mm上锪90°×φ9沉孔。 本模具冲制过程:冲二孔φ5.6mm及12×10长方形孔——锪90°沉孔——落料。 模具结构如图2,采用对角线导柱模架,模具压力中心为57.6mm。冲孔凸模φ5.6mm,12×10mm由件5、6和锪孔90°     

高强度钢热成形模具及温度控制系统研究

高强度钢热成形的核心技术包括模具结构设计和温度控制系统设计两部分,而板料加热变形后的淬火和冷却速度是该工艺成败的关键。因此,亟须研发能实现最佳淬火和冷却工艺的模具及相应的温度控制系统。以带凸缘的盒形件为研究对象,首先计算了热成形模具的凸、凹模圆角半径和凸、凹模间隙,然后进行了热成形凸模、凹模以及压边圈具体结构和冷却水路的设计,最终研发出了热成形模具温度控制系统的自动控制方案和装置。     

PQ35发动机支架压铸模具的设计和改进

介绍了PQ35发动机支架压铸模具的设计、模具材料的选择和热处理、浇注和排溢系统的设计、加热和冷却系统的设计以及试模后发现的问题和工艺参数的调整等。支架模具主分型面在底平面上方3mm处,两侧和后端设有3个抽芯机构,依靠液压油缸实现抽芯。选择偏心的分支浇道,并将浇道设置在动模一侧。在浇道的末端和两侧金属液汇集区域分别设置集渣包。模具的加热和冷却由导热油和冷却水共同控制。     

大型塑料注射模讲座

<正> 第四讲 加热冷却系统的设计 模具温度调节有两个目的,一是提高成型率和生产效率,二是提高制品质量。注射成型时把200℃左右的塑料注入模腔内,固化后模温降低到50～60℃时取出制件。这个温差不很好调节,不但影响熔料充模,且易使制品翅曲和开裂。模具内快速冷却定型,     

塑料碗注射模冷却系统设计与分析

分析了塑料碗的注射模型和注射模的结构,采用田字形和s形冷却水路,设计冷却系统;对比两种水路冷却方案,分析冷却10min后塑料碗的温度场分布、钢模具块表面和内部温度场的分布,得到S形冷却方案优于田字形,为了实现更好冷却效果,提出优化模型。分析管道流和传热方程,得到冷却影响因素,并用优化模型分析温度场分布及验证了水力流速、管道材料、表面粗糙度对冷却起着决定作用。     

简易螺纹型芯自动脱模机构

<正> 本文介绍一种利用直角式注射机的倒顺牙锁模螺杆来旋出螺纹型芯的模具结构,经生产实践证明,螺纹型芯能顺利地脱出工件。 如图1所示,模具主要由定模3、动模4和螺纹型芯脱模机构三大部份组成。螺纹型芯脱模机构包括方轴11、主动轮5、被动轮6、定距板13和定距螺钉8,模具结构详见图1。 注射后,经过一定时间冷却,开启模具,随动模移动至定距螺钉8允许的距离,因主动轮5连接的方轴11插入成型机的锁模     

Ti（50）Ni（47）Fe3形状记忆合金冷轧变形后的组织与性能

采用拉伸测试、维氏硬度测试、电阻率-温度曲线测试及扫描电镜和透射电镜观察显微组织的方法研究冷轧变形量为25%的Ti50Ni47Fe3合金经450-750°C下1 h退火后的显微组织和性能。结果表明,冷轧变形增强了合金的抗拉强度和屈服强度,冷轧变形后形成的应力场有助于R相变的发生。随着退火温度的升高,合金的抗拉强度和屈服强度下降,伸长率增大;当退火温度高于650°C时,强度和伸长率趋于稳定。电阻-温度曲线表明,在升、降温过程中发生两阶段相变B2-R-B19′。随着退火温度的升高,合金的相变温度降低;当退火温度高于650°C时,相变温度趋于稳定。随着退火温度的升高,合金依次发生回复、再结晶和晶粒长大。     

Growth behavior of ultrafine austenite grains in microalloyed steel

Ultrafine austenite grains (UFAGs) with size of 1–5 μm were prepared through repet- itive treatment, four times, of rapid heating and quenching, and the growth behaviors of these UFAGs during both the reheating and cooling stages were investigated. The results indicated that UFAGs without pinning particles appeared with significant coarsening when the reheating temperature reached 1000 °C. Although coarsening still occurred in the cooling stage, the growth was obscured during the isothermal holding process ...     

Effect of Sintering Temperature and Heating Rate on Crystallite Size,Densification Behaviour and Mechanical Properties of Al-MWCNT Nanocomposite Consolidated via Spark Plasma Sintering

Powder mixture of ball-milled aluminium and functionalized multi-walled carbon nanotubes was compacted via spark plasma sintering(SPS) to study effects of sintering temperature and heating rate. An increase in sintering temperature led to an increase in crystallite size and density, whereas an increase in heating rate exerted the opposite effect. The crystallite size and relative density increased by 85.0% and 14.3%, respectively, upon increasing the sintering temperature from 400 to 600 °C, whereas increasing the heating rate from 25 to 100 °C/min led to respective reduction by 30.0% of crystallite size and 1.8% of relative density. The total punch displacement during SPS for the nanocomposite sintered at 600 °C(1.96 mm) was much higher than that of the sample sintered at 400 °C(1.02 mm) confirming positive impact of high sintering temperature on densification behaviour. The maximum improvement in mechanical properties was exhibited by the nanocomposite sintered at 600 °C at a heating rate of 50 °C/min displaying microhardness of 81 ± 3.6 VHN and elastic modulus of 89 ± 5.3 GPa. The nanocomposites consolidated at 400 °C and 100 °C/min, in spite of having relatively smaller crystallite size, exhibited poor mechanical properties indicating the detrimental effect of porosity on the mechanical properties.     

热处理对TC21合金组织形貌演变的影响

研究固溶温度及冷却速率对TC21合金组织演变的影响,采用定量软件对组织特征参数、晶粒大小、α相面积和片层厚度,及初生α相面积和次生α相厚度进行定量表征。结果表明,β相区处理时,随着固溶温度的升高,晶粒尺寸增大,且炉冷(FC)条件下晶粒长大的程度比包覆冷却(BC)的大(FCBC)。两相区热处理时,随着两相区热处理温度的升高(800～850℃),α相的总面积增加;在900～930℃固溶后,包覆冷却条件下,初始次生α相逐渐消失,α相总面积减小,而炉冷后,新的"羽毛"片状α相从β基体中大量析出,α相总面积反而增加。从动力学理论角度分析冷却速率对晶粒尺寸及α相体积分数变化的机制。     

Effect of Heat Treatment on Microstructures and Mechanical Properties of Hot-Dip Galvanized DP Steels

In order to simulate the hot-dipped galvanizing of dual-phase(DP) steel(wt%) 0.15C–0.1Si–1.7Mn, the DP steels were obtained by different annealing schedules. The effects of soaking temperature, time, and cooling rate on ferrite grain, volume fraction of martensite, and the fine structure of martensite were studied. Results showed that the yield strength(YS) of DP steel is sensitive to annealing schedule, while total elongation has no noticeable dependence on annealing schedule. Increasing soaking temperature from 790 to 850 °C, the YS is the lowest at soaking temperature of 850 °C. Changing CR1 from 6 to 24 °C/s, the YS is the highest when CR1 is 12 °C/s. Increasing soaking time from 30 to100 s, the YS is the lowest at soaking time of 100 s. Besides, it was found that sufficient movable dislocations within ferrite grains and high martensite volume fraction can eliminate yield point elongation, decrease the YS, and increase ultimate tensile strength. Through TEM observations, it was also found that increasing annealing temperature promotes austenite transformation into twin martensite, and increases volume fraction of martensite at sufficient cooling rate. With increasing the martensite volume fraction, the deformation substructure in the ferrite is well developed.     

Effect of Cooling Rates in Coiling Process on Microstructures and Mechanical Properties in Al-Bearing Hot-Rolled TRIP Steel

In this study, the effect of cooling rates on microstructures and mechanical properties in a Al-bearing hot-rolled transformation-induced plasticity steel was investigated. The experiments were carried out using hot simulation machine and hot rolling mill, where the samples were cooled at different cooling rates. The results showed that with the increase in cooling rates, film-like retained austenite gradually disappeared and only blocky retained austenite was retained at higher cooling rates. The volume fraction of retained austenite was 9–11% at cooling rates of 0.05–1°C/s and 4–6% at cooling rates of 5–10 °C/s. In addition, martensite/austenite island was observed because of the heterogeneous carbon distribution. The samples cooled at 0.05 °C/s and 0.5 °C/s exhibited excellent mechanical properties, with tensile strengths of 712 MPa and 726 MPa, total elongations of 42% and 36% and strength and ductility balances of 29.91 GPa% and 26.15 GPa%, respectively. During plastic deformation, the instantaneous work hardening exponent of the sample cooled at 0.05 °C/s increased continuously until it reached the maximum value, while the instantaneous work hardening exponent of the sample cooled at 0.5 °C/s remained stable.     

冷却条件对超声振动法制备AZ91半固态浆料组织的影响(英文)

利用超声振动法制备AZ91合金半固态浆料,在不同温度区间和冷却速率下对熔体进行超声处理,研究冷却条件对AZ91半固态浆料微观组织的影响。结果表明:在形核阶段,熔体在超声振动引发的空化和声流效应作用下,能够获得细小、近球状的初生α-Mg固相颗粒;在固液相线温度区间内,随着超声温度下限的降低,半固态浆料的固相率和固相颗粒的平均尺寸增加;在超声振动过程中,随着冷却速率的提高,半固态浆料的固相率增大,固相颗粒的平均形状因子降低。在本实验条件下,适宜的超声振动温度区间为605°C到595°C或590°C,合适的冷却速率为2~3°C/min。     

Influence of Deformation Degree and Cooling Rate on Microstructure and Phase Transformation Temperature of B1500HS Steel

To study the effects of the deformation degree and cooling rate on the microstructure and phase transformation temperature for the B1500 HS steel, the samples were heated at 900 °C for 5 min, compressed by 10, 20, 30 and 40% at the strain rate of 0.1 s~(-1), and then cooled down at the rates of 50, 40, 25, 20 and 15 °C/s by the thermo-mechanical simulator,respectively. The start and finish temperatures of the phase transformation were determined by the tangent method, and the volume fraction of the phase transformation was ascertained by the level principle according to the dilatometric curves.The volume fraction of the retained austenite was determined by X-ray diffraction. The results show that the volume fraction of the bainite rises with an increase in the deformation degree as the cooling rate is lower than the critical rate. At the same cooling rate, the phase transformation temperature rises with an increase in the deformation degree, and the sizes of both the martensite and bainite phases reduce due to the austenite grain refinement induced by the deformation. The volume fraction of the retained austenite reduces as the deformation degree increases. The critical cooling rate of the undeformed samples is approximately 25 °C/s and the critical cooling rate rises as the deformation degree increases.     

FEM Simulation of the Hydrogen Diffusion in X80 Pipeline Steel During Stacking for Slow Cooling

The influence of temperature on the hydrogen diffusion behavior in X80 pipeline steel during stacking for slow cooling was studied using electrochemical penetration method, the temperature field and the hydrogen diffusion in this pipeline steel during stacking for slow cooling were simulated by ABAQUS finite element method(FEM) software. The results show that in this process there is a reciprocal relationship between the natural logarithm of hydrogen diffusion coefficient and temperature. The cooling rate decreases gradually with the increase of steel plate thickness. The hydrogen content is higher at high temperature(500–400 °C) than that in low temperature region(300–100 °C). The FEM simulation results are consistent with the experimental ones, and the model can be used to predict the hydrogen diffusion behavior in industrial production of X80 pipeline steel.     

Grain refinement in a cast high Nb containing TiAl alloy by heat treatment

The grain refmement of an as-cast Ti-46Al-8.5Nb-0.2W (atom fraction in %) alloy by the cyclic heat treatments was studied. The heat treatment scheme included a tempering at 1250℃ and cyclic tempering at 1000 and 1200℃ three times after solution treatment at the temperature above α phase transus followed by immediate fan cooling. The fine and homogeneous near-γ microstructure can be obtained by this heat treatment, which causes the breakdown of as-cast microstructure and prevents the anomalous growing of originalγ phase.