首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 78 毫秒
1.
30CrMnSiA和30CrMnSiNi2A钢超高温淬火组织与性能的研究   总被引:3,自引:0,他引:3  
研究了30CrMnSiA、30CrMnSiNi2A钢超高温淬火组织与力学性能关系。试验结果表明,在该钢Ac3以上-200℃超高温淬火可获得组织细小均匀的板条马氏体加残余奥氏体。控制超高温淬火加热保温时间,毁唯奥氏体化又能获得细小奥氏体晶粒,从而显著提高了该钢的强韧性。  相似文献   

2.
7Cr2WMoVSi钢热处理过程的碳化物的变化   总被引:7,自引:0,他引:7  
本文研究了7Cr2WMoVSi钢热处理过程的碳化物的变化,结果表明,随退火温度降低,碳化物尺寸减小,780~800℃退火获得均匀细化的球化组织;加热至940~980℃奥氏体化时,M3C,M23C6已全部溶解,仍存在M6C和较多的VC剩余碳化物,有效地阻碍了奥氏体晶粒长大,随回火温度升高,按M3C,M23C6,M6C,VC依次沉淀析出,各类碳化物的不同析出过程,提高了钢的回火抗力。  相似文献   

3.
一种CrMnN不锈钢中碳化物等温沉淀动力学的研究   总被引:2,自引:0,他引:2  
用膨胀仪、化学定量相分析(CPA)及TEM方法研究了ZG0Cr13Mn8N钢奥氏体中碳化物的等温沉淀动力学。结果表明,依据等温不同时间析出碳化物引起的Ms温度变化可更方便,更准确地测出奥氏体中碳化物等温沉淀动力学曲线;在900 ̄580℃范围内ZG0Cr13Mn8N钢中碳化物等温析出的鼻尖温度为800℃,相应的孕育期为2400S;碳化物主要以M23C6型沿晶界或夹杂物边界析出。  相似文献   

4.
本文研究了710-840℃之间的30CrMnSiA钢的恒温超塑性。重点测试了在共析转变点Acl点附近的超塑性指标。研究结果表明,30CrMnSiA钢具有恒温相变超塑性特性,在Acl点温度附近材料延伸率有明显增长,流动应力最低。当初始应变速率为4.2×10^-4s^-1时,经预先调质处理的30CrMnSiA钢最大延伸率为608%,最低流动应力为55MPa,与710-740℃温度区间内的研究结果相比延  相似文献   

5.
用TEM研究了新型钎钢40MnMoV的正火组织,发现它与Si-Mn-Mo系的另一种钎钢55SiMnMo相似,由无碳化物上,下贝氏体Bu、Bl、以孪晶马氏体为主的“块状组织”和约15%残余奥氏体Ar组成,但40MnMoV的Bu,Bl较多,Ar和L则较少;Bu板条较粗大,其间分布着不连续的A小片条;Bl片中有渗碳体与粤氏体A共存;L的尺寸较小,硬度较低,讨论了该钢正火时贝氏体(B)相变的原因及影响贝氏  相似文献   

6.
以30CrMnMoTiA钢及30SiMnMoVA钢为研究对象,进行了晶界侵蚀剂的试验,提出了用相补金相观察法来提高晶粒对比度的观点和方法。  相似文献   

7.
凌斌  钟炳文 《材料工程》1995,(7):31-32,10
观察分析了冷却速度对低合金超高强度钢(40CrMnSiMoVA)精细组织的影响。结果表明,在冷却、低温等温(或回火)过程中,钢显微组织中的马氏体或贝氏体存在时效阶段。其组织特征为呢纹花样。α和ε间的取向不满足Jack关系,它属一种新的取向关系。过渡型碳化物可直接从呢纹花样区析出。  相似文献   

8.
激光扫描速度对40Cr钢表面组织结构的影响   总被引:3,自引:0,他引:3  
对调质态的40Cr钢试样用CO2连续波输出激光速进行相变硬化处理,用穆斯堡尔谱学方法研究了激光扫描速度对试样表面层组织结构的影响,结果表明,40Cr钢激光硬化层的组织为马氏体,残余奥氏体和少量未溶碳化物。随激光扫描速度增大,试样中的马氏体和未溶碳化物的含量不断增加,残余奥氏体含量则连续下降。  相似文献   

9.
研究了热轧以相钢Fe-0.078C-1.44Mn-1.11Si-0.38Cr经不同温度回火后的显微组织变化。透射电镜观察表明:热轧双相钢的组织中不可避免地混有少量珠光林(<5%),它们对钢的基本力学性能并没有多大影响。本钢种200℃回火组织中,马氏体基本不变化,为板条态,双相钢仍保持屈服行为;300℃回火组织中,大量马氏体发生分解,形成碳化物,与少量珠光体交界处的马氏体首先发生分解。该温度回火完全  相似文献   

10.
7Cr7Mo3V2Si钢加热相变研究   总被引:1,自引:0,他引:1  
利用Formastor全自动相变测定仪研究了7Cr7Mo3V2Si钢在连续加热条件下的相变规律及特点;测定了能反映其相变规律与特点的奥氏体形成图。结果表明,钢中球状珠光体向奥氏体的转变是在较宽的温度区间(Ac1b-Ac1e)内完成的;钢中大量合金碳化物的溶解、按其难易程度不同分别与n个溶解温度相对应;连续加热条件下,奥氏体难以实现均匀化。  相似文献   

11.
A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.  相似文献   

12.
Permeable crystalline materialcan permeate into pores and cracks of concrete and catalyze the reaction between Ca(OH) 2and unhydrated cement to generate a great quantity needle non-soluble crystals, which can stop up the pores and cracks of concrete, and increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate steel reinforcement corrosion of concrete specimens uncoated and coated with permeable crystalline material as well as mixed with the permeable crystalline material. The properties evaluated for corrosion test were water impermeability, water absorption, compressive strength and potential. The results of water impermeability, water absorption, compressive strength clearly showed that the permeable crystalline material could prohibit water, any soluble salts and moisture from penetrating the concrete to cause corrosion, leaking, and other problems, and it did increase the compressive strength, which was favorable for protection of corrosion of reinforcing steel. Moreover, it was concluded from the potential-time curve that the steel reinforcement of uncoated specimen was in the state of activation whereas that of other specimens coated and mixed with the permeable crystalline material was in the state of inactivation. Above all, it was indicated that the permeable crystalline materialis very effective to protect the steel reinforcement of concrete from corrosion.  相似文献   

13.
In this paper, the principle of spurting take off lacquer were introduced; and with orthogonal method the unsaturate polyester was prepared ;it was easy to peel airplane paint layer off with this material and equipment.  相似文献   

14.
Quality Study of Honeycomb Core Shaping Without Wax Stabilization   总被引:1,自引:0,他引:1  
Sandwich panels utilizing honeycomb cores result in lightweight, high-strength units that are very rigid. Indeed, they give honeycomb panels the best strength-to-weight ratio of any construction type available. Conventionally, the wax is poured into the cell of the core to strengthen the structure and prevent the core from being crushed during milling. Much time and labor is required to wax, mill, and clean the cores. In this study, the process of pouring wax into the core was skipped. In other words, the cutter directly milled the core. Experiments showed that the compressive strength of the core produced without wax stabilization was only 3% lower than that of cores produced using the traditional method. In addition, the drum peel strengths of cores produced without wax stabilization were 38.4% higher than cores produced using the traditional method, in which residual wax seriously polluted the adhesive. It was also found that eliminating the wax process can reduce costs.  相似文献   

15.
The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……  相似文献   

16.
Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.  相似文献   

17.
Polylactic acid (PLA) is one of the most widely used open source fused filament fabrication materials due to its ease of extrusion, biodegradability, and mechanical strength. The mechanical strength of PLA largely depends on the proper growth of its semi-crystalline structure, which can be severely impaired by a low rate of crystallization, particularly in open source printers. This can be further aggravated by the non-uniform thermal distribution of heat that causes improper curing among the extruded beads of the printing material. As a result, PLA printed on open source printers does not achieve the best mechanical properties. This research, for the first time, proposes an additive-free solution implemented through a detailed set of experimentation to improve the curing rate through in-process temperature variations to cure the joints among the beads. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy is used to confirm the improvements in the bead joints. This work is conducted in two phases of experiments. In the first phase, a full factorial ANOVA is used to investigate various process parameters and the important variables are used in the second phase to print test specimens in four different sets.  相似文献   

18.
We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.  相似文献   

19.
Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.  相似文献   

20.
ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号