焊后低温热处理对马氏体不锈钢组织和性能的影响

对ZG06Cr13Ni4Mo马氏体不锈钢进行了焊后低温热处理工艺试验(240、300 ℃),通过显微组织分析、拉伸及弯曲试验、硬度试验及残余应力测试对不同低温热处理下焊接接头的显微组织、力学性能、硬度和残余应力等进行了研究。结果表明,经低温热处理后,接头焊缝热影响区组织为回火马氏体及碳化物,接头焊缝区的组织为低碳马氏体+块状马氏体+碳化物,接头的抗拉强度变化不大,硬度略有下降,经240 ℃低温热处理后,焊接接头焊缝处的残余应力消除了69.1%。     

35CrMnSiA超高强钢的焊接性试验研究

采用MIG焊焊接超高强钢35Cr Mn Si A,对热处理前后焊接接头组织进行分析,并对热处理后焊接接头进行了硬度测试、拉伸试验、冲击试验及断口分析,从而研究分析了35Cr Mn Si A的焊接性。结果表明:焊态下,焊缝区组织为针状马氏体和少量残余奥氏体,热影响区组织为板条状马氏体、贝氏体和残余奥氏体;热处理后,焊缝组织为回火马氏体和残余奥氏体,热影响区组织为回火马氏体、少量贝氏体和残余奥氏体;焊接接头焊缝区的硬度高于热影响区和母材;焊接接头抗拉强度为1640.8 MPa,伸长率为9.2%,焊缝区冲击功为37.6 J,焊缝区的冲击断口为混合断口。     

聚变堆用CLAM钢激光焊接接头显微组织及性能

对聚变堆用CLAM钢进行了激光焊接试验,并对接头进行740℃/1 h焊后回火处理,分别对热处理前、后接头的显微组织及性能进行了研究.结果表明,获得了成形良好、无缺陷的焊接接头;焊态下,焊缝由淬硬的板条马氏体和大量的δ铁素体组织组成.完全淬火区由板条马氏体和极少量的δ铁素体组成,其硬度高达545 HV;焊后热处理使焊缝及完全淬火区的板条马氏体分别转变为碳化物弥散分布的回火马氏体和回火索氏体组织.显著降低了接头的淬硬程度,最大硬度仅比母材高约15%;焊后回火热处理前、后接头的抗拉强度均高于基体母材,虽然焊后热处理使接头强度有所降低,但仍达到原始母材的98%以上.     

12Cr1MoV钢硬度超标焊缝的组织性能研究及原因分析

通过力学性能测试、金相组织检验及扫描电子显微镜观察等分析了某火力发电机组12Cr1MoV钢硬度超标焊缝的显微组织和力学性能。试验研究结果表明:12Cr1MoV钢硬度超标焊缝的强度高、塑性低、冲击韧性较差;焊缝硬度超标是由于焊后热处理恒温温度不足所致;焊缝硬度超标会使该材料焊接接头产生再热裂纹的倾向增大,容易出现早期开裂失效;采用较小的焊接热输入、有效的焊后热处理、减少接头部位的应力集中是减少12Cr1MoV钢焊接接头再热裂纹的有效措施。     

20CrMn2SiMo钢与20CrNi3Mo钢摩擦焊接头的组织和性能

研究了20CrMn2SiMo钢与20CrNi3Mo钢摩擦焊焊接接头的组织和力学性能。结果表明,未进行热处理时,其焊缝区显微硬度最高,热影响区其次,母材硬度最低;热处理后,焊缝和基体组织均为板条状贝氏体和马氏体以及少量的残余奥氏体,焊缝区和基体硬度基本相同;热处理后的焊接接头具有良好的强韧性:σb=1351MPa,δ5=11%,ψ=43%。     

35CrMnSi钢电子束焊接头显微组织和力学性能研究

研究了35CrMnSi 钢电子束焊接头的组织和力学性能.试验结果表明:该钢电子束焊焊缝为典型的针状马氏体+残余奥氏体组织,HAZ为中温组织;2种厚度钢板焊接接头各区域的硬度值基本一致,且焊缝硬度高于热影响区的,热影响区的硬度高于母材的.经电子束焊后,2种厚度35CrMnSi钢板接头塑性比母材的塑性低,这与其显微组织有关;35CrMnSi钢电子束焊焊缝的冲击韧度低于母材.     

00Cr13Ni5Mo不锈钢的焊接裂纹敏感性试验研究

采用小铁研试验对正火及正火+回火态的00Cr13Ni5Mo马氏体不锈钢进行了焊接冷裂纹敏感性研究。焊接接头微观组织和显微硬度分析结果表明,两种热处理状态条件下的00Cr13Ni5Mo马氏体不锈钢均有良好的抗冷裂纹敏感性,正火态马氏体不锈钢焊后热影响区发生明显软化,正火+回火态焊后接头硬度则为焊缝区至母材区逐步降低的趋势。     

超高强度钢35CrMnSi惯性摩擦焊接头组织与性能

对35CrMnSi超高强度钢进行了惯性摩擦焊试验研究,对热处理前后焊接接头组织、显微硬度进行分析测试,并对热处理后焊接接头进行了拉伸性能、冲击性能及拉伸断口分析。结果表明:焊后接头焊缝组织为板条马氏体与残余奥氏体,热力影响区组织为细小的马氏体、索氏体、珠光体和铁素体混合组织;热处理后焊缝组织为回火马氏体与少量铁素体;摩擦焊接头焊缝区的硬度高于热力影响区和母材,热处理后焊接接头硬度趋于一致,焊接接头抗拉强度大于1 890 MPa,断后伸长率大于7. 5%,焊缝区拉伸断口为混合断口;焊接接头冲击吸收能量大于18. 5J。     

热处理对1Cr18Ni9Ti与2Cr13钢板焊接接头耐腐蚀性的影响

通过填丝钨极氩弧焊方法对1Cr18Ni9Ti与2Cr13钢板进行焊接,并对焊接接头进行焊后热处理。采用SEM对焊接接头热处理前后的组织进行观察及分析;采用模拟海水浸泡试验,测量了焊接接头的交流抗阻和极化曲线。结果表明,1Cr18Ni9Ti和2Cr13钢板焊接接头热处理前焊缝为典型的柱状晶,组织为板条马氏体+奥氏体+第二相;热处理后焊缝组织为回火索氏体+奥氏体+第二相。热处理前后,焊接接头耐腐蚀性由强到弱的顺序都为:奥氏体母材>奥氏体侧热影响区>焊缝区>马氏体侧热影响区>马氏体母材。对比而言,热处理后焊接接头中马氏体母材区的耐蚀性略有升高,其他区域均有下降。     

SK5钢闪光对焊工艺研究与应用

针对SK5钢开展闪光对焊试验,对其焊接接头的显微组织、拉伸性能、显微硬度、弯曲性能进行分析,探索合适的SK5钢闪光对焊焊接生产工艺。结果表明,采用合适的焊接工艺参数,可以获得优质的闪光对焊焊接接头,焊缝区组织由针状和片状马氏体+残余奥氏体组成,热影响区组织由针状和片状马氏体+少量铁素体组成,生成硬脆的片状马氏体组织,组织脆化;焊后进行200℃低温回火处理后焊缝区生成低碳马氏体组织,热影响区生成低碳马氏体和回火马氏体组织,焊接接头组织得到改善,同时其拉伸性能及弯曲性能得到提升。采用合适的闪光焊工艺条件,焊后200℃低温回火处理,能够满足SK5耐磨环焊接应用要求。     

胫骨生物陶瓷复合材料的微结构增韧机理

扫描电镜观察显示胫骨是一种由羟基磷灰石和胶原蛋白组成的自然生物陶瓷复合材料.羟基磷灰石具有层状的微结构并且平行于骨的表面排列.观察也显示这些羟基磷灰石层又是由许多羟基磷灰石片所组成,这些羟基磷灰石片具有长而薄的形状,也以平行的方式整齐排列.基于在胫骨中观察到的羟基磷灰石片的微结构特征,通过微结构模型分析及实验,研究了羟基磷灰石片平行排列微结构的最大拔出能.结果表明,羟基磷灰石片长而薄的形状以及平行排列方式增加了其最大拔出能,进而提高了骨的断裂韧性.     

Prospects of the Use of Synergetic Approach to Solution of Problems of the Science of Nanomaterials

A synergetic approach to solution of problems of self-controlled synthesis of nanostructures and creation of self-organizing nanotechnologies is considered in connection with the superproblem of creation of materials with functional properties resembling those of biosystems. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 55 – 61, July, 2005.     

Kinetics of the oxidation of metals — Influence of self-diffusion of metal

The importance of the self-diffusion of a metal during its oxidation by a gas is treated for the cases of nonstoichiometric oxides having either interstitial cation or cation vacancies. We have established a general relationship for the reaction rate when a mixed diffusion process occurs. From this relationship, we have shown that the pressure dependence can be different, according to whether the rate-determining process is the self-diffusion through the metal or through the product.     

Features of formation of the structure in production of blanks of disks of heat-resistant nickel alloys

Conclusions To provide a high level of mechanical properties in wrought blanks of cast ÉP741NP and ÉP962 alloys it is necessary to form controlled structures. A necklace-type structure formed in homogenizing isostatic treatment, subsequent thermomechanical working including alternation of the operations of deformation in the (+)-area and recrystallization anneals, and final heat treatment is preferable. The temperature conditions of all stages of thermomechanical working are strictly controlled, especially the final operation of deformation and heating for hardening. To eliminate hardening cracks and distortions it is necessary to use molten salts at t=600°C as quenchants. The use of multiple production operations makes it possible to significantly reduce the structural inhomogeneity related to inhertance of the original dendritic structure. However, the structure of the final semifinished product is nevertheless characterized by a difference in occurrence of the processes of polygonization and recrystallization between the former dendritic cells and the interdendritic spaces in deformation and heat treatment.To obtain structurally homogeneous blanks for gas turbine engine parts it is necessary to use basically new methods of remelting such as vacuum double electrode remelting and electron beam remelting with an intermediate vessel.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 25–29, December, 1991.     

Ab-initio calculation of enthalpies of formation of intermetallic compounds and enthalpies of mixing of solid solutions

A large number of ab-initio calculations of energies of formation of intermetallic compounds have been performed in the last 15 years. The currently used methods are listed. The paper presents a review of the aluminium based compounds which have been studied. Comparisons of calculated and experimental enthalpies of formation are provided for aluminim-3d and-4d transition metal alloys at equiatomic composition. The modelling of the enthalpies of mixing of solid solutions based on a given lattice is described.     

试论洋务派教师聘任的思想

洋务派在洋务学堂的办学活动中,为了解决西学专业学科的教学困难,采用了聘请外籍教师的应急措施.他们以真才实学,合同制管理作为主导思想,并认为这种解决师资的途径只是权宜之计,并非久远.从客观上看,洋务派的教师聘任思想有深刻的历史影响.