低氢型铁粉高效焊条的研制

研制了一种优质高效,低尘低毒,以CaO-CaF2-TiO2为渣系的低氢型铁粉高效焊条。从工艺性能、物理化学性能等方面分析了熔敷金属的化学成分对熔敷金属的抗拉强度和低温冲击韧性(-20℃)的影响规律。     

磁场对双丝间接电弧形态的影响

对双丝间接电弧在自身磁场及外加磁场变化的情况下,电弧形态随磁感应强度值的变化规律进行了研究.自身磁场变化通过改变两焊丝夹角角度实现,外加磁场由励磁线圈产生,对间接电弧施加横向及纵向磁场,磁场强度利用特斯拉计测出,并借助高速摄像系统对磁场变化时的电弧形态进行拍摄.研究表明,通过改变两焊丝夹角及施加横向磁场的方式,可使两焊丝所夹区域内外磁场强度之差变大,使得电磁力的外扩作用增大,电弧变细长;施加纵向磁场时,电弧在与两焊丝垂直的平面内发生偏转,其偏转程度随纵向磁场强度增加而增加.     

Amorphization of Fe38Ni30Si16B14V2 surface layers by laser cladding

Fe38Ni30Si16B14V2 amorphous composite coatings were fabricated by laser cladding on AISI 1045 steel in order to increase the wear resistance. The phase and microstructure of the coatings were analyzed by X-ray diffractometry and transmission electron microscopy. The wear properties of the coatings were also investigated by means of sliding wear test. The results show that the coating consists of amorphous phase in majority and nanocrystalline phase in minority. The amorphous coatings can be obtained while the scanning speed is 3 500 mm/min and the laser power is 4.8 kW. With increase of the laser power, the amorphous phase in the coating increases when it is lower than 4.8 kW. A gradient distribution of the microhardness ranges from Hv0.2 1 208 to Hv0.2 891 in the coating from top surface of the coating to the substrate. The amorphous coating is found to possess better property of wear than AISI 1045 steel substrate.     

激光熔覆Fe基非晶／纳米晶复合涂层的组织与性能

对以激光熔覆方式在45钢基体上制备的FeNiSiBVRE非晶涂层进行激光晶化,制备非晶／纳米晶复合涂层,利用X射线衍射仪、透射电镜、扫描电镜和磨损试验机研究非晶／纳米晶复合涂层的组织与性能,研究结果表明,涂层存在着分层结构,组成相有晶化相、非晶相和纳米晶相;涂层底部和顶部的显微组织由大量的稀土树枝晶、板条状硼化物和粒状碳化物组成,涂层中部的显微组织是由大量的纳米晶相镶嵌在非晶基体上构成,与没有进行激光晶化的非晶涂层相比,涂层的耐磨损性能下降,其磨损机制以粘着磨损和剥层磨损为主。     

双电极焊条两芯间距和焊接电流对单弧焊工艺的影响

研究了钛钙型双电极焊条的两芯间距和焊接电流对单弧焊工艺的影响 .研究结果表明 ,钛钙型双电极焊条的两芯间距是控制焊接电压的最重要因素 ,焊接时调节双电极焊条与工件间距离对电弧电压影响很小 ,随双电极焊条两芯间距的增大 ,电弧电压升高 ;在两芯间距一定的条件下 ,随焊接电流增大 ,电弧电压线性升高 ;对于药皮重量系数为 45.6%的 2×Φ4mm钛钙型双电极焊条 ,在两芯间距为 1.2～ 1.7mm ,焊接电流为 180～ 2 2 0A的工艺条件下进行焊接 ,焊缝成形较好 ,力学性能满足国家标准的要求     

Development of new type of wear and crack resistant hardfacing electrode

By using H08A bare electrode and the coating fluxes of ferrotitanium, rutile, graphite, calcium carbonate and calcium fluoride, a new type of wear and crack resistant hardfacing electrode was developed. The microstructure and wear properties of deposited layer were studied by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry(XRD) and wear test. The results indicate that TiC particles are produced by direct metallurgical reaction between ferrotitanium or rutile and graphite during welding process. TiC particles with sizes in the range of 3 - 5μm are dispersed in the matrix of lath martensite and retained austenite. The deposited layer of the new type of hardfacing electrode possesses better wear and crack resistance than that of D618 and D667 hardfacing electrodes.     

TiC-VC免预热耐磨堆焊焊条

采用H0 8A焊芯 ,钛铁、钒铁、人造金红石和石墨等药皮组分 ,研制了新型耐磨、免预热堆焊焊条。通过扫描电镜 (SEM)、能谱分析 (EDAX)、磨粒磨损试验、焊条工艺性能试验以及硬度测试 ,系统地研究了焊条药皮组分对堆焊层耐磨性、抗裂性、工艺性能及堆焊层组织结构的影响。试验结果表明 ,通过电弧高温冶金反应 ,,药皮中Fe -Ti、Fe-V与石墨反应生成TiC、VC硬质相 ,并弥散分布于低碳马氏体 残余奥氏体的基体上 ,堆焊层具有良好的耐磨性和抗裂性 ,焊前不预热 ,连续堆焊堆焊层不产生裂纹。Fe-Ti、Fe -V与石墨的加入量对堆焊层耐磨性、硬度以及工艺性能影响很大 ,随着钛铁、钒铁、石墨量增加 ,堆焊层硬度、耐磨性增加。但药皮中钛铁超过 18%后焊条工艺性能变差 ,石墨超过 12 %后 ,堆焊层耐磨性降低     

双电极焊条单弧焊飞溅的研究

利用高速摄影等实验手段，研究了双电极焊条单弧焊熔滴过渡形态、熔滴受力、双芯间隙、焊条套筒形式、双电极焊条焊接时运条方式等对飞溅的影响。     

稀土在金属陶瓷/铜基合金复合堆焊材料中的变质作用

运用扫描电镜和透射电镜试验观察与理论计算分析相结合 ,研究了WC基金属陶瓷 /铜基合金复合堆焊材料中稀土La对堆焊层的变质和净化作用。研究结果表明 ,稀土La与氧作用形成高熔点的稀土化合物 ,作为铜基合金非均匀形核的核心是有效的 ,能抑制晶粒长大而细化组织。稀土元素具有脱氧作用 ,减少氧化物夹杂 ,消除缺陷 ,提高堆焊层的冲击韧性。具有高能表面的稀土化合物质点 ,促使金属陶瓷与铜基合金界面上形成微晶过渡层 ,提高界面结合强度     

白口铸铁焊补温度场的数值模拟

应用有限元方法建立了白口铸铁焊接接头焊补温度场的数学模型,对白口铸铁焊补温度场和热循环进行了分析。研究结果表明：焊后初期冷却速度很快（约４００℃／ｓ）;焊补接头的温度分布极不均匀;热影响区中特别是靠近熔合区处存在较大的温度梯度,是焊接接头产生裂纹的重要因素。计算值与实测值进行了对比,结果基本吻合