201 CS焊丝的应用试验

选用201 CS焊丝采用埋弧堆焊工艺进行不同厚度的埋弧堆焊试验,焊后热处理。通过检测焊后硬度和金相组织达到要求,拟确定该焊丝的应用。     

电火花堆焊工艺在冲压模具维修上的应用

介绍了电火花堆焊设备及工艺在冲压模具维修中的使用情况,为大型冲压模具成形面拉伤修复探索出了一种新方法。     

JH70车架左右半体模具维修经验

以JH70车架左、右半体成形模、切边模为例,对模具维修产生的刃磨寿命低、模具拆装不方便、刃口堆焊开裂等问题,采取切实可行的解决措施,使模具总寿命和刃磨寿命得到较大提高并促使产品质量得到较大改善。根据生产现场模具维修实际情况,指出大型模具设计中应注意的问题以及改进的可行措施。     

粉末合金喷涂工艺在模具修复中的应用

粉末合金喷涂工艺是我国八十年代发展起来的一种金属表面热喷涂新工艺。至今已开发应用有镍基、铁基、铜基、钴基等三十多个品种,主要含化学成分有Ni、W、Al、Cr、B、Si、C等几十种化学元素,熔融后可获得HRC 65以内的各种硬度值。碳化钨型粉末合金在基体硬度为HRC60时,粉末合金熔融后硬度可达HRC70。各种粉末合金根据工件的需要可获得良好的韧性、高耐磨性、耐蚀性和低摩擦系数等机械性能。随着工厂保军转民的不断深入,模具制造也不断向大型化、复杂化方面发展,经济投入不断扩大,国外在此情况下普遍采用粉末合金喷涂工艺和堆焊技术提高模具使用寿命,减少模具消耗量和降低模具投入成本,从而提高企业经济效益。采用粉末合金喷涂工艺和堆焊技术可使模具寿命致少提高一倍以上。     

油田用双金属机械复合管失效原因分析与对策

目的 分析研究双金属机械复合管的失效原因,并提出改进措施。方法 对比说明双金属机械复合管几种常见的典型制造方法及其优缺点,介绍应用中典型传统焊接工艺焊接的环焊缝腐蚀剌漏或穿孔、环焊缝开裂、内衬塌陷或鼓包以及爆管等常见的失效形式,利用现场应用的失效实例、统计数据和室内检测结果,分析这些失效类型的原因,并提出针对性建议或措施。结果 双金属机械复合管几种典型的制造方法各有优缺点,但其产品的内衬与基管的结合力均较小。造成其管材失效的主要原因有高压、高温、含CO2/Cl^–腐蚀介质、封焊结构、焊接工艺、外防腐层施工、应力腐蚀或电偶腐蚀等。根据现场应用实践,提出并应用了管端堆焊结构、环焊缝用镍基合金焊材、增加内衬厚度和小管径等防止失效的建议或措施,取得很好的防护效果。结论 造成此类管材失效的因素有腐蚀、封焊结构、焊接、外防腐施工及应力腐蚀或电偶腐蚀等,可采取堆焊结构、镍基合金焊材、厚衬层和小管径等措施。     

诗意湿地

大凡河湖名川,都有其独特的风姿和神韵,或广袤,或静谧,或清秀,或磅礴,或激荡,或委婉,林林总总,形形色色,各自彰显着与众不同的个性.如果说地球上生物进化经历了一个由水域向陆地的变迁,那么湿地则见证生命发生的全部过程.不仅如此,湿地作为水陆在时空坐标上的交替界面的特别区域、唯一的"四圈交汇"之地(水圈,生物圈,岩石圈,大气圈),湿地独特的自然禀赋所赋予的使命更为深远,在目睹了自然生命变迁的同时,也目睹了人类文明盛衰、社会兴亡演替的历历往事.     

清洁生产是控制环境污染的有效途径

末端治理在防治污染过程中起一定作用,取得了一定的成绩,但实践证明,末端治理模式在不同方面存在明显不足,不能有效防治污染,清洁生产的引入,使环保史上发生一场革命,清洁生产是一种全程的污染防治,即经济又有效,要全面推广还存在一定的困难,需各部门共同努力.     

到长白山去(一)

到长白山一定要看天池。但能否看到天池要凭缘分。导游说,不知道有多少游客兴致勃勃而来,最后却扫兴而归。天池就在那里静静地躺着,已经有千万年,上山的路途虽然艰险,但还不至于难于上青天,怎么还见不到天池呢?原来,长白山上真正是一岭分四季,十里不同天,忽云忽阴,睛雨不定;游客乘车、步行,翻山越岭,好不容易到达山顶,极有可能遇上云雾缭绕或者大雨倾盆,将天池的本来面目遮掩住。或者,干脆就被大雨挡在半路,连上山的机会都丧失掉。     

惯性(小小说)

每天的17:30分,我们乘坐的班车在下班号响后会准时驶出厂门,出了厂门的右侧有个站,这儿是机关干部的上车点. 由于班车从我们车间始发,近水楼台先得月,我便有了固定的座位,一个位于车尾,靠窗的单座.而每天经过厂门口停站时,总会上来一个人,站在我边上,伸出一只毛茸茸的手抓住扶手.从那一身将校呢的制服上,我了解到他是厂武装部长,姓王,今年初刚转业到我们厂工作.     

打破僵局

"我们拔了18吨,仍不见动静,请领导拿意见."4月13日,当河南油田井下作业二部副经理靳水生和工艺人员赶到L1256井场时,201修井队技术员范红禅立即向他们汇报拔钻解卡情况. "好,再拔拔看!"听到指令,司机汪佳柱启动30吨斜井作业机,一手扶离合器手柄,一手握刹把,脚踩油门,两眼紧盯指挥手势.作业机吼叫着,掐着油管的"脖子"使劲往上拽,那架势如同一场拔河比赛.压力器指针指向了18吨,油管还是一动不动.     

30CrMnSiNi2A超强钢激光熔覆修复试验研究

目的研究激光熔覆技术,解决30CrMnSiNi2A钢制部件表面腐蚀、划伤、裂纹等缺陷的修复问题。方法利用光纤激光器在30CrMnSiNi2A钢表面进行同基体相近成分的合金粉末熔覆试验,优化激光熔覆工艺参数,开展熔覆层的微观组织、硬度、力学性能等方面试验研究,并对拉伸试样的断口进行分析。结果熔覆层与基体呈现牢固的冶金结合,基体热影响区域小,熔覆区的抗拉强度大于基体强度的80%,熔覆区材质的脆性较基材有所增加。结论激光熔覆可用于修复30CrMnSiNi2A钢制零件表面的腐蚀、划伤、裂纹等局部缺陷。     

Microwave cladding: A new approach in surface engineering

Cladding is generally characterized by partial dilution of the substrate and hence formation of metallurgical bonding between the substrate and the deposits. Laser cladding is one of the most widely practiced surface engineering techniques. The present work mainly focuses on a novel development in surface engineering techniques in the form of microwave cladding. Clads of tungsten carbide (WC) based WC10Co2Ni powder on austenitic stainless steel were produced using microwave hybrid heating. Microwave clads were developed by exposing the preplaced, preheated powder for a duration of 120 s to microwave radiation at 2.45 GHz frequency and 900 W power in a home microwave system. Characterization of the clads was carried out in the form of microstructural and elemental composition studies. Investigations show crack-free interface revealing good metallurgical bond associated with partial dilution of the stainless steel substrate and full melting of WC particles. Typical X-ray diffraction results confirm presence of metallic carbides in the clad which is primarily responsible for significantly higher microhardness of the clad. Process mechanism has been discussed.     

Microstructure of 2205 duplex stainless steel joint in submerged arc welding by post weld heat treatment

The 2205 duplex stainless steel (DSS) is of both good properties austenitic steel and ferritic steel, which applies to the shipbuilding industry usually. In this paper, the OM, XRD and microhardness test methods are used to analyze the variation of submerged arc welded (SAW) joints with and without post weld heat treatment (PWHT). The research results show that the σ phase disappear in the fusion edge zone near heat affect zone (HAZ) and an increase in the welded center zone during the follow-up PWHT, while the amount of γ phase is decreased in the welded center zone with PWHT. A segregation distribution of some second phases is also found in the welded center zone after PWHT. There have two pick values of microhardness arise in the fusion edge zone and the welded center zone separately without PWHT. However, a maximum value of microhardness at the fusion edge zone near HAZ is disappeared and the other is still held at the welded center zone during PWHT. It can be attributed to the changes of second phases, element diffusions and particle segregation during PWHT. A developing mechanism is issued to demonstrate the second phases transferring of the 2205 DSS SAW joints by PWHT.     

记忆光塑性法在包覆腔塑变区研究中的应用

记忆光塑性法是一种新的网格实验方法，文中首次应用记忆光塑性法对连续挤压包覆腔塑变区的流动特性进行研究，发现进入汇合腔的铝料大致分为三个方向流动，最后达到在芯线的四周均有材料向包覆模内流动，从而在锥形包覆模内形成轴对称挤压状态，有利于保证包覆产品的同心度。     

Development and characterization of microwave composite cladding

The development of cladding through microwave radiation is recently explored and very few, initial studies were reported elsewhere. In order to explore more viability of process, (EWAC (Ni based) + 20% Cr₂₃C₆ powder) composite cladding has been developed on substrate austenitic stainless steel (SS-316). The experiments were conducted in domestic microwave oven and the clad of thickness, approximate 500 m has been developed by the exposure of microwave radiation at frequency 2.45 GHz for duration of 360 s. Typical clads cross sections of composite clads showed good metallurgical bonding with the substrate by partial dilution. The back scattered electron image of clad cross section showed the reinforced chromium carbide (Cr₂₃C₆) particles are uniformly distributed and well embedded in the Ni based matrix. The developed clad is free from visible solidification cracking and has significantly less porosity which is of the order of 0.90%. The XRD pattern of the developed clad showed the presence of FeNi₃, NiSi and Cr₂₃C₆ phases. The average Vicker's microhardness of developed clad was observed as 425 ± 140 Hv.     

Effect of mechanical surface treatments on Ti–6Al–4V direct metal deposition parts

The effect of surface treatments, including aggressive milling, rotational burnishing, and nonrotational burnishing, on Ti–6Al–4V DMD (direct metal deposition) parts was investigated. Particular emphasis is on the question of whether these surface treatments could induce the plastically deformed and work-hardened layer that was proven to enhance the fatigue resistance of titanium alloys and was a key step for recrystallization. Through the microhardness examination and microstructure analysis, it was found that the rotational burnishing process was able to work harden the material deeper than 1000 μm, while the work-hardened layer generated by the nonrotational process was ∼600 μm and that for aggressive milling was less than 10 μm. Because surface finish is another critical factor for the resistance of fatigue crack initiation, it was also evaluated for these treatments.     

稀土元素对38CrMoAl钢离子渗氮工艺的影响

目的缩短38CrMoAl钢离子渗氮工艺周期。方法在离子渗氮过程中,添加稀土金属镧(La)及稀土镧铈合金(La-Ce)。通过显微硬度仪、光学金相显微镜、扫描电镜及能谱分析仪对于离子氮化层的表面硬度、脆性、微观显微组织、稀土元素含量进行检测分析,并和常规离子渗氮工艺进行对比研究。结果在离子渗氮工艺过程中,添加稀土金属镧(La)及镧铈合金(La-Ce)后,氮化层表面硬度提高约130～200 HV,渗氮速度提高了15%～30%,氮化周期显著缩短。稀土催渗离子渗氮层的脆性均为Ⅰ级,比常规离子渗氮更优异。同时,稀土元素的渗入细化了晶粒,使得渗层氮化物组织致密、呈弥散分布,优化了氮化层的相结构组成。结论稀土元素的加入可以有效提高渗氮层的表面硬度和脆性等级,改善了氮化层性能。同时缩短了离子渗氮工艺周期。     

烧结多孔管的制作及其沸腾传热研究

目的研究烧结多孔管表面多孔层的制造工艺,并对铜粉烧结多孔层表面的传热性能进行测定。方法利用烧结模具在铜管外面烧结铜粉层,并通过实验计算出多孔烧结管的热通量和强化换热系数。结果铜粉烧结后的铜管在酒精中的强化传热效果达到了光管的10倍左右。结论烧结铜粉粒径越小,烧结管的热通量越大,其传热性能越好。     

双向微槽道多孔复合结构沸腾传热研究

目的研究出新型的表面结构,以提高沸腾传热强化。方法在紫铜板上烧结铜粉多孔层,然后利用线切割对多孔层进行开槽。研究槽道参数包括槽数、槽宽、槽间距和槽向等对沸腾传热效果的影响。结果开槽增大了传热的表面积,有利于气体逸出,减少气体的逸出阻力,从而多孔表面开槽强化了沸腾传热效果,传热系数与光滑表面相比可提高2~3倍。与单向微槽道相比,双向交叉槽道有着更好的传热效果,能够形成一个稳定的液体补充和气体逸出网络。结论在多孔表面加工微型复合结构,能够大幅度提高沸腾传热强化。     

Investigation on microstructural and mechanical properties of microwave processed dissimilar joints

In the present work, microwave joining of stainless steel (SS-316) to mild steel (MS) in bulk form has been successfully carried out using a multimode applicator at 2.45 GHz and 900 W. Principles of hybrid heating were employed using a susceptor medium so as to initiate coupling of microwave with the metals. A nickel based metallic powder was used as a sandwich layer between the bulk pieces. Samples were exposed to microwave radiation in atmospheric conditions. Resulting joints were characterized using field emission scanning electron microscope (FESEM), X-ray diffractometer, microhardness tester and universal testing machine. Microstructure study showed the faying surfaces were well fused and got bonded on either side of the base material. Formation of cementite and metallic carbides were evidenced. The average observed Vickers’ microhardness of core of the joint area was observed to be 133 H_v with 0.58% porosity. The ultimate tensile strength of the joint was found to be 346.6 MPa with percentage elongation of 13.58%. Fractography reveals that the joints failed due to both shearing of the brittle carbides and oxides as well as due to plastic flow of the ductile matrix under tensile loading.