Introducing oxide particles into martensitic stainless steel (MSS) can significantly enhance the material’s comprehensive mechanical properties. However, the traditional powder metallurgy process suffers from prolonged preparation cycles and low material utilization rates, which severely limit its industrial scalability and further development. As an emerging manufacturing technology, arc additive manufacturing (AM) effectively overcomes these drawbacks. This study therefore proposes an innovative and rapid fabrication approach based on an oxide coating strategy, enabling the uniform incorporation of submicron spherical oxide particles (Y2O3, TiO2) during wire arc additive manufacturing (WAAM) of 1Cr13. This method facilitates efficient material deposition and enables precise control over microstructure and performance. Experimental results show that temperature gradients lead to a non-uniform distribution of martensite, tempered martensite, and ferrite within the matrix. Upon the addition of Y2O3 particles, fine Y2O3 dispersoids are uniformly distributed throughout the matrix without significantly altering the base microstructure. When both Y2O3 and TiO2 particles are introduced simultaneously, Ti-Y-O composite oxides and Ti-rich oxides are generated within the matrix, which further refine the oxide particle size, reduce the grain size of the deposited layer, and increase the dislocation density. The presence of these uniformly dispersed submicron oxides substantially enhances the material’s room-temperature hardness and tensile strength, while significantly improving its high-temperature tensile performance at 600 °C.

Due to its remarkable strength and toughness, 42CrMo steel finds extensive application in shipbuilding as well as various industrial sectors. Nevertheless, it exhibits inadequate surface corrosion resistance and is prone to damage from prolonged exposure within marine environments. In order to improve its surface corrosion resistance, multi-pass nickel–aluminum bronze (NAB) alloy deposition layers were prepared on the surface of 42CrMo steel using wire arc additive manufacturing (WAAM) technology, and the effect of overlap rate on the microstructure and properties of the deposition layers was investigated thoroughly. The results show that the CuAl8Ni2/42CrMo bimetallic deposition exhibits excellent metallurgical bonding and properties. The deposited layer contains various phase structures of α-Cu phase, β/β′ phase, and weak κ phase. With the increase in overlap rate, the microstructure of the overlap region changes with the increase in iron-rich dendrites and coarse columnar crystals, and the increase of element diffusion at the interface. The microhardness of the deposited layer peaks at 40

Diffusion bonding technology was used to realize the connection of 42CrMo steel and tin bronze, and the effects of bonding time and nickel interlayer on the microstructure and mechanical properties of the joint were studied. The results show that: When 42CrMo steel and tin bronze are directly diffusion bonded, at 850 ℃ and 4MPa, the shear strength of joint first increases and then decreases with the increase of bonding time. When the bonding time is 60 min, the thickness of the diffusion layer is about 0.5μm, the shear strength of the joint reaches a maximum of 152MPa, and the fracture shows mixed fracture characteristics of brittleness and ductile. After adopting Ni foil as the interlayer metal, both 42CrMo steel/Ni and Ni/tin bronze interfaces formed obvious diffusion layers of about 11 μm and 50 μm, respectively, a granular discontinuous distribution of (Cu,Ni)3Sn formed on the Ni/tin bronze side, the shear strength of the joints is elevated up to 221 MPa, and the fracture is characterized by ductile fracture.

Nickel-based self-lubricating composite coatings (Ni60/Ag(Cu)/nanoNi/h-BN) with different amounts of Nb were manufactured by laser cladding on the surface of 42CrMo steel. The effects of carbide forming element Nb on the microstructure evolution and tribological properties of the composite coatings were investigated. The results show that Nb is easily precipitated at grain boundaries and reacts with carbon to form the in-situ synthesized phase NbC. The grains were refined and rich substructures appeared inside, which improved the strength and hardness of the coatings. The average microhardness of the coatings with 5.5 wt% Nb addition reaches 731.5H3/0.2, which is 192.1H3/0.2 higher than that of NCA0(0 wt%), and 3.17 times that of the substrate. Compared to NCA0, the average friction coefficient and wear rate of NCA3 decreased by 38.1% and 30.6%, respectively. The solid lubricant formed a lubricant film during wear, and the fine grains facilitated oxidation wear, resulting in the formation of oxidation film. The lubricant film, oxidation film and the increase in hardness together improved the tribological properties of the coating.

High-strength steel (42CrMo) is frequently used to manufacture components under high load and high friction conditions. To improve the surface tribological properties, nickel-based alloy coatings with Ag(Cu)/nanoNi/h-BN nanosheets were prepared on the surface of 42CrMo steel by laser cladding technique. The effects of Ag(Cu) and nanoNi/h-BN on the microstructure evolution, hardness and friction-reduction properties of the cladding layer were discussed. The results show that the coating microstructure changes significantly. The addition of micron Ag(Cu) and nanoscale Ni/h-BN increased the nucleation rate of the melting pool, and the columnar dendritic crystals were transformed into fine cells. The addition of nanoparticles enabled the coating to obtain a higher microhardness of 575.4HV0.2, which is about 1.4 times of the substrate. The mechanical properties of the coating were improved, and the friction coefficient and wear rate were significantly reduced, with good friction-reduction property. The wear mechanism mainly consists of a composite wear of slight adhesive wear, abrasive wear and oxidation wear.

A laser cladding technique was employed to produce a Fe50-XMn30Co10Cr10NbX (X = 2.5, 5, 7.5, 10at%) high entropy alloy coating. This study delved into the influence of Nb concentration on the coating's phase constitution, microstructural features, hardness, and wear resistance. The high entropy alloy coating exhibited a multifaceted structural composition, encompassing FCC (Face-Centered Cubic), HCP (Hexagonal Close-Packed), and BCC (Body-Centered Cubic) structures, along with the presence of Laves phase. Notably, the incorporation of Nb led to an augmentation in the Laves phase and modifications within the microstructure. The hardness of the cladding layer is higher than that of the substrate. With the increase of Nb content, the hardness of the cladding layer increases first and then decreases; the average hardness of the Fe42.5Mn30Co10Cr10Nb7.5 cladding layer is the highest, the maximum hardness is 429.8Hv, and the average hardness is 382.3Hv. The friction coefficient and weight loss of the cladding layer decreases first and then increases with the increase of Nb content. The friction coefficient and weight loss of the Fe42.5Mn30Co10Cr10Nb7.5 cladding layer are the smallest, which are 0.0132 g and 0.5974, showing the best wear resistance. The wear types of high entropy alloy cladding layer are both adhesive wear and abrasive wear. The addition of Nb into high entropy alloy will form the Laves phase, which can improve the mechanical properties of high entropy alloy.

The preliminary experimental results show that the laser cladding technology can produce a well-formed single-layer lead bronze cladding layer with a thickness of 250 mu m. The ideal process parameters of the single-layer laser cladding test were selected to study the multi-layer cladding, and the microstructure and properties of the multi-layer cladding were evaluated. The results show that, the multi-layer cladding is composed of alpha-Cu, Cu41Sn11, Cu5.6 Sn, Pb, and SnO2 phases. There are fine equiaxed crystals at the top of the cladding layer while columnar crystals growing perpendicular to the fusion line at the bottom. The maximum hardness of cladding layer is 248.2 HV near the bottom fusion line. The wear mechanism of multi-layer cladding layer combines abrasive wear and adhesive wear, with wear weight loss and average friction coefficient of 0.0025 g and 0.1161, respectively. The average shear strength between the substrate and the cladding layer is 129 MPa, the shear fracture mode is ductile fracture. Compared with single-layer cladding, the anti-friction performance of multi-layer cladding is significantly improved.

针对7003铝合金和AZ31镁合金两种金属进行搅拌摩擦焊工艺试验,研究不同焊接速度、搅拌速度、轴肩下压量等焊接工艺参数对其搭接接头微观组织、力学性能性能、断口形貌的影响.结果表明,后退侧Hook尺寸明显大于前进侧Hook尺寸且更为曲折,搅拌区内主要由网格状的Al12Mg17组成,网格内部由镁基体和Al12Mg17共同组成,前进侧上空存在一个沿水平方向延伸的金属间化合物(intermetallic compounds,IMCs)薄层;焊缝表面随着转速的提升变得光滑,后退侧Hook尺寸明显增加;行进速度过大会导致冶金反应不充分,焊缝表面出现犁沟,搅拌区底部出现隧道;下压量增大会使接头机械互锁程度增加,当下压量、焊接速度或旋转速度增加时,有效承载面积增大,拉剪力随着搭接接头有效承载面积的增加有不同程度提升;拉剪力最大值(4.02 kN)出现在950-30-0.7参数下,断裂方式为解理脆性断裂;焊缝中心由于Al-Mg金属间化合物的生成,硬度最高为144.8HV0.05.

为了探索不同激光工艺参数对铅青铜熔覆层成形质量的影响,采用激光熔覆技术在42CrMo钢表面制备铅青铜熔覆层,并分析了熔覆层微观组织、硬度和减磨性能.结果表明,激光功率240 W、扫描速度5 mm/min为最优工艺参数,采用此工艺参数制备出的铅青铜熔覆层成形质量良好,组织致密、无气孔裂纹;铅青铜熔覆层组织主要由马氏体、α-Cu固溶体、CrMo3S4、Pb相组成;熔覆层平均硬度为334HV0.1;熔覆层试样的磨损类型为黏着磨损和磨粒磨损的复合磨损形式.

Abstract A two‐step process, including the premetallization of the SiC ceramic by Ag‐26.7Cu‐4Ti+B4C and the followed brazing with the Al‐based filler alloy, was developed to join 2219 aluminum alloy and the metallized SiC. The influence of metallization temperature and the B4C addition on the microstructure and mechanical properties of the joint was analyzed. The reaction products of Ti and B4C were detected in the brazing seam, such as Ti2B, TiC and graphite. With increasing of metallization temperature and B4C addition content, the shear strength of joint first increased and then decreased. The joint shear strength reached 14.0 MPa when SiC metallized with Ag‐26.7Cu‐4Ti+1%B4C at 930°C for 10 min, which showed that appropriate addition of B4C in Ag‐26.7Cu‐4Ti metallization layer could regulate the coefficient of thermal expansion difference between 2219 aluminum alloy and SiC to relieve the residual stress and improve the shear strength of their brazed joint.

In this study, Al–70Si alloy was prepared by laser cladding. The effect of microstructure on the mechanical and thermo-physical properties was elucidated by comparing specimens prepared by laser cladding and casting methods. It is found that the laser cladding process can effectively reduce the formation of coarse primary silicon, which inevitably occurs in large quantities in cast samples. Therefore, various properties have been significantly improved. The tensile strength reaches 85 MPa, the thermal conductivity at room temperature is 76.6 W/(m·K), and the coefficient of thermal expansion (CTE) is 8.19 × 10−6/K. In addition, the solid solution treatment is able to spheroidize the primary silicon and passivate the sharp corners. The change in Si phase morphology can greatly reduce stress concentration and increase the degree of interfacial bonding. This resulted in an increase in tensile strength and thermal conductivity of 50.7

在304L不锈钢表面采用激光熔覆法制备了Fe50-xMn30Co10Cr10Nbx(x=0,5)高熵合金熔覆层,通过添加Nb元素和不添加Nb元素进行对比试验,研究Nb元素对于熔覆层组织和性能的影响.研究表明,采用激光熔覆法制备的高熵合金熔覆层顶部为细小的等轴晶,而靠近基体部分则为柱状晶;Nb元素的加入能够促进Laves相产生,提高了高熵合金熔覆层的硬度和耐磨性,Fe45Mn30Co10Cr10Nb5熔覆层的硬度最高可达357.6HV0.05,约为Fe50Mn30Co10Cr10熔覆层最大硬度的1.2倍,Fe45Mn30Co10Cr10Nb5熔覆层磨损失重相比Fe50Mn30Co10Cr10减少约27％.研究结果可为提高304L不锈钢表面性能提供一定的试验依据.

Fe 50 Mn 30 Co 10 Cr 10 high-entropy alloys were prepared by laser cladding technology. The microstructure and phase structure of the cladding layer were analyzed. The effects of laser cladding parameters on mechanical property of the cladding layer were studied. The results show that, the Fe 50 Mn 30 Co 10 Cr 10 high entropy alloy cladding layer is composed of FCC structure and HCP structure, BCC structure was also observed in the layer. There are fine equiaxed grains at the top of the cladding layer while columnar grains near the fusion zone. The maximum hardness of cladding layer is 292.9 HV under the laser cladding parameter of 200 W and 5 mm/s. The maximum tensile strength of the substrate with cladding layer is 692.4 MPa, and the maximum elongation is 21.3%. The fracture mode of cladding layer is ductile fracture. Adhesive wear and abrasive wear are both observed at surface of the cladding layer after wear testing. The best wear resistance is obtained at cladding parameter of 200 W, 7 mm/s with the weight loss of 0.0215g and friction coefficient of 0.6294. The results provide a certain support for the preparation process and microstructure, properties analysis of Fe 50 Mn 30 Co 10 Cr 10 high entropy alloy.

针对5052铝合金/AZ31镁合金,进行了异种搅拌摩擦焊搭接试验,通过宏观和微观分析、硬度和拉剪力测试探究了Zn中间层对于铝/镁搭接接头组织和性能的影响.结果显示,焊缝搅拌区底部形成了厚度较均匀的金属间化合物(intermetallic compounds,IMCs)层,未加Zn层时,IMCs层由铝基体、尺寸较大呈条带状的Al3Mg2及网格状Al12Mg17化合物组成,拉剪力为3.9 kN,断裂方式为解理脆性断裂;加入Zn层后,IMCs厚度随Zn中间层厚度的增加而增加,IMCs层厚度最小为330μm,内部主要由网格状Al12Mg17组成,网格状内部出现了小尺寸颗粒状的Mg-Zn以及Al-Mg-Zn IMCs;焊缝截面水平方向,搅拌区硬度为160HV,垂直方向硬度值最高达210HV,拉剪力最大值为4.79 kN.研究表明,生成的Mg-Zn和Al-Mg-Zn IMCs是导致拉剪力较未加Zn层时提高20％的主要原因.

Fe 50 Mn 30 Co 10 Cr 10 high-entropy alloys were prepared by laser cladding technology. The microstructure and phase structure of the cladding layer were analyzed. The effects of laser cladding parameters on mechanical property of the cladding layer were studied. The results show that, the Fe 50 Mn 30 Co 10 Cr 10 high entropy alloy cladding layer is composed of FCC structure and HCP structure, BCC structure was also observed in the layer. There are fine equiaxed grains at the top of the cladding layer while columnar grains near the fusion zone. The maximum hardness of cladding layer is 292.9 HV under the laser cladding parameter of 200 W and 5 mm/s. The maximum tensile strength of the substrate with cladding layer is 692.4 MPa, and the maximum elongation is 21.3%. The fracture mode of cladding layer is ductile fracture. Adhesive wear and abrasive wear are both observed at surface of the cladding layer after wear testing. The best wear resistance is obtained at cladding parameter of 200 W, 7 mm/s with the weight loss of 0.0215g and friction coefficient of 0.6294. The results provide a certain support for the preparation process and microstructure, properties analysis of Fe 50 Mn 30 Co 10 Cr 10 high entropy alloy.

使用放电等离子烧结技术,以V-Ni复合粉末中间层,研究了在30 MPa、1050℃和Ni质量分数为40％的条件下不同保温时间(10 min,20 min,30 min)对钨和MA956钢扩散连接性能的影响.不同保温时间下扩散焊接的接头界面连接良好,中间层区域由于Ni3V和NiV3等金属间化合物的产生,硬度值最高约为550HV.扩散层中靠近钢侧脆性碳化物VC使得其硬度高于钢母材,同时造成了钢母材靠近中间层区域脱C并软化.保温时间为20 min时,接头的剪切强度达到225 MPa,剪切试样均断裂在中间层区域靠近钨侧处.

A two-step process involving, the pre-metallization of the SiC ceramic by Ag-Cu-Ti foil and the Al based filler alloy was developed to join 2219 aluminum alloy and the metallized SiC. The composition of metallized SiC layer was investigated. The effect of metallization temperature on the microstructure and mechanical properties of the joint was analyzed. The brazing process showed that Al from the brazing filler and 2219 substrate reacted with Ag-Cu-Ti alloy to form intermetallic compounds. Al3Ti, Al2Ag and Al2Cu were detected in the joint. Ti5Si3, TiC and Ti3SiC2 compounds were found adjacent to the reaction layer of the Ti and SiC. With increasing of metallization temperature, the shear strength of joint first increased and then decreased. The joint shear strength reached 16.0 MPa when the pre-metallization temperature reached 1000 degrees C and holding time was 10 min.

为了研究工艺参数对H13钢表面激光熔覆高熵合金成型和性能的影响,通过在H13钢表面激光熔覆Co1.5CrFeNi1.5Ti0.75高熵合金,并分析了不同激光功率和扫描速度参数下熔覆层的形貌、相组成、硬度和耐磨性.研究表明,高熵合金Co1.5CrFeNi1.5Ti0.75熔覆层为BCC相和FCC相;当激光功率为200 W、扫描速度为300 mm/min时,熔覆层成形良好,平均硬度最高,耐磨性能也最好.相关结果为提高H13钢的表面性能提供了有效、可实施的方法和试验依据.

采用Ti-Cu复合中间层扩散连接钨与CLAM钢,在30 MPa、1h和800～950 ℃的条件下,成功获得了W/Ti-Cu/CLAM钢接头.接头界面连接良好,中间层区域发现有Ti2Cu或TiCu4等金属间化合物产生.TiC脆硬层使得中间层/钢界面处的硬度远高于钢母材,同时造成了接头处钢母材的失C并软化现象.随焊接温度的升高,接头的剪切强度先升高后降低,在850 ℃时达到了274 MPa的最大值,剪切试样均断裂在W/中间层界面靠近钨侧处.