高碳高铬堆焊焊条的研制及其堆焊合金显微组织分析

为了研制具有优良耐磨性能和硬度的高强钢耐磨堆焊焊条,设计了焊条药皮的配方,选用了焊条药皮的渣系,分析了药皮成分对焊接飞溅的影响规律。对研制的堆焊焊条（Fe-Cr-C、Fe-Cr-C-Nb）进行了焊接试验。试验结果表明,焊条药皮元素显著影响堆焊熔敷合金焊缝的气孔、飞溅等性能指标。显微组织分析表明,碳含量及铬－碳比对耐磨合金的碳化物方向、密度等分布状态起到决定性影响,随着其含量的增加,碳化物趋向垂直于堆焊层表面方向分布,合金的显微硬度和耐磨性不断提高,硬度最高值达到63HRC,相对磨损率为0.05;Nb元素的增加对显微硬度影响不大,但能使碳化物得以细化,分布更均匀,可以显著改善合金的耐磨性。     

电弧沉积条件下Cu基熔覆层的微观组织及性能研究

为了优化Q345B低碳钢的表面使用性能,设计相应的药芯焊丝并采用TIG沉积方法制备了Cu基熔覆层,通过OM、SEM、EDS、XRD和显微硬度测试等方法,研究了Cu基熔覆层的微观组织、元素分布、物相组成、界面元素扩散和表面硬度等。结果显示,在成分过冷的影响下,Cu基熔覆层由界面至顶部形成了不同的晶粒形貌。熔覆层主要由FCC结构的Cu-Ni-Cr-Fe固溶体、富Cr析出相和单质C元素组成,其中,由于微观偏析的存在,固溶体内元素分布不均匀,Ni、Fe元素主要富集在枝晶内,在枝晶间浓度较低;富Cr析出相主要以球状或棒状分布在基体上,少量单质C也在基体内均匀分布。研究表明,得益于合金元素的固溶强化和第二相粒子的第二相强化作用,熔覆层平均硬度达到202.8 HV0.1,高于纯铜和Q345B基体。     

大型阀门耐腐蚀层的堆焊与加工工艺研究

为了提高碳钢铸造阀体内部的耐腐蚀性能,需要在其内表面堆焊耐腐蚀层。对DN500阀体进行三维实体建模,估算出阀体质量及内表面积。设计了阀体内表面的堆焊工艺,通过堆焊厚度和内表面积估算出焊条用量,又设计了阀体配合面的堆焊与加工工艺,对加工尺寸链进行计算,既保证了配合精度,又保证了耐腐蚀层的厚度。结果表明,通过对大型阀门的三维建模,估算制造成本的方法是可行的并具有实际工程意义;配合表面的堆焊与加工工艺能够在保证耐腐蚀层厚度的基础上达到配合要求;采用普通铸钢并堆焊耐腐蚀层制造的阀体,比全不锈钢阀体成本可降低30%以上。     

Low Power Laser Surfi-Sculpt

The functional properties of materials can be enhanced using surface features,for instance;to improve the thermal properties of heat exchangers.The development of the laser Surfi-Sculpt process over the past decade has resulted in a technology capable of producing a wide variety of features in metallic substrates.Furthermore,the potential for producing similar features in polymeric and ceramic substrates also exists.Recently the potential for utilizing high power focused laser beams to produce surface features using this process has been demonstrated.This paper details the results of recent trials performed with a 200 Yb-fibre laser and a galvanometer driven beam scanner for producing surface features using the Surfi-Sculpt process.A compact,cheap,easily robotically automated,laser Surfi-Sculpt machine,being able to operate at atmospheric pressure may have potential in a range of industry sectors.     

Calculation and experimental evaluation of the service life of welded joints in a nodular graphite cast iron pipeline for mechanical loading conditions. Part I ‐ experimental procedure and material

The main types of flux-cored strip electrode materials for mechanized arc surfacing of alloyed and composite alloys are discussed. Surfacing with these strips results in the formation of the required properties of the working surfaces of components. Special features of the melting and formation of the deposited layer with the required welding and technological properties are also discussed, taking into account the production technology of flux-cored strips.     

Using brazing alloys in resistance spot welding of joints in aluminium–magnesium alloys

The results of mathematical modelling of the process of propagation of heat in the parent metal in submerged-arc surfacing with a composite strip electrode are presented. The mathematical model was constructed by solving the differential equation of heat conductivity by the finite element method. The calculations and plotting of the graphs were carried out using the MSC Patran software. The model was used to determine the main parameters of the composite strip electrode influencing the shape and dimensions of the pool and the non-uniformity of penetration. The comparison of the calculated and experimental data shows that they are in good agreement.     

Investigation of metallurgical processes in pulsed laser welding of nickel alloys of small thickness

Metallurgical processes taking place in pulsed laser welding of nickel alloys of small thickness are described.     

The microstructure of composite cermet coatings produced by carbo-vibroarc surfacing

The results of investigation of the microstructure of composite coatings produced by carbo-vibroarc surfacing using cermet pastes are presented. It is shown that the composite cermet coating consists of two zones – the main and transition. The main zone of the coating contains the Fe₂B hardening phase with nickel and chromium atoms implanted in the crystal lattice of the phase. The zone is situated in the matrix of the solid solution of iron and nickel Ni₃Fe. The transition zone of the coating is formed by the mutual diffusion of the coating and the substrate and consists of the (Fe, Ni)₂B hardening phase and the Ni₃Fe matrix. It is also shown that the hardening phases form plate-shaped grains with thicknesses of 1–4 μm and more than 100 μm long, distributed in the form of colonies throughout the entire volume of the coating zone. In the direction to the transition zone, the shape of the structural components changes to circular with the diameter of up to 5 μm.     

碳化钨喷焊层耐磨性的研究

本文重点研究了碳化钨与粘结金属的配合比例、碳化物颗粒的粒度、粘结金属的组织成分及其硬度等因素对喷焊层耐磨性的影响,并初步得出某些因素对喷焊层耐磨性的影响规律。还对碳化钨喷焊层在静载与动载磨粒磨损条件下的表面形貌进行了细致地观察与分析,并对磨粒磨损的机理进行了探讨,为正确地选用碳化钨喷焊层提供了依据。     

大型45铸钢齿轮专用耐磨堆焊焊条的研制

根据矿山机械、水泥机械等大型齿轮磨损堆焊性能的要求，有针对性的研制出了具有耐冲击、金属间接触疲劳磨损的堆焊焊条。这种焊条的堆焊层组织是奥氏体基体上分布着碳化物、硼化物硬质相，有较高的塑韧性和加工硬化效应，它既有高抗裂性，又有良好的耐磨性，工艺性也优良，是一种应用范围较大的新型耐磨堆焊材料，该种焊条用于直径等大型齿轮（４５铸钢件）表面堆焊后的实际运转考核中表明：齿轮运转正常，耐磨性能良好，经济效益高。