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2024, Volume 39,  Issue 2

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Additive Manufacturing
Study on Abrasive Flow Polishing Process of Aluminum Alloy and High-temperature Alloy Microchannels by SLM Additive Manufacturing
LI Hui, LI Weina, QI Junfeng, LI Jingyang, ZHANG Jianchao, ZHANG Jianxun
2024, 39(2): 1-8,16.
[Abstract](12) [PDF 12162KB](6)
Abstract:
The metal additive manufacturing technology represented by the laser selective zone melting (SLM) technology makes the surface of the products very rough due to the inherent "powder adhesion" and "spheroidisation effect", which makes it difficult to meet the usage requirements. Facing the rough bore surface of SLM microfluidic channel, we adopt the abrasive flow polishing technology to polish the inner surface of AlSi10Mg and GH4169 microfluidic channels prepared by SLM, and investigate the effect of abrasive flow process on the surface roughness and dimensional accuracy of microfluidic channel bores. The results show that after the abrasive flow treatment, the surface qualities of the bores of both the aluminium alloy and high temperature alloy fabricated by SLM additive manufacturing are effectively improved, and the roughness of the micro-runner bore surface decreases by more than 50 %. The surfaces of the runner bores are clean with no attachments. There is no large change in the runner dimensions, and the dimensional accuracy is retained at a relatively high level. Therefore, the abrasive flow process is an effective polishing technique for SLM additive manufacturing of micro-runner structure parts.
Research on Preparation, Microstructures and Mechanical Properties of Hot-Pressed Laminated Mg-Li Alloy Sheets
WANG Wei, PU Lili, HUO Yuhan
2024, 39(2): 9-16.
[Abstract](16) [PDF 8845KB](16)
Abstract:
The LAY821 alloy self-designed is to used to prepare LAY821 alloy sheets for hot-pressing laminated additive manufacturing via extrusion and rolling processes. The microstructures and mechanical properties of the alloy are investigated to provide theoretical and technical foundations for expanding the application of Mg-Li alloy in additive manufacturing. The microstructures are observed by metallurgical microscope and SEM. The phase compositions of the alloy are analyzed by XRD and detected using EDS. The mechanical properties of the alloy are tested by tensile test. The results indicate that the LAY821 alloy as-cast and as-deformed are composed of α-Mg and β-Li phases, and Al2Y phase distributed along the grain boundaries and among the α-Mg phase. After extrusion, rolling and intermediate annealing treatment, the alloy develops a homogeneous doublephase equiaxial crystal structure, with an average diameter reduction from 11.6 μm to 7.0 μm. The Al2Y particles are diffusely distributed, withan average diameter reduction from 2.2 μm to 1.0 μm. No new phases are found in the XRD test results. The tensile property of the alloy exhibit 290.26 MPa of UTS, 54.74HV of hardness, and more than 30 % of elonga-tion. The improvement of the mechanical properties is due to the refined equiaxial crystalline structure and the dispersion strengthening effect of Al2Y. The structure of the LAY821 alloy sheet for the hot-press laminated additive manufacturing is controllable, and the mechanical properties show no obvious anisotropy.
Research Status and Prospect of Additive Manufacturing Technology of Ship Aluminum Alloys
WANG Hao, LIU Kun, WU Hong, ZHOU Junbo, LI Jie, ZHANG Qinglin
2024, 39(2): 17-27,43.
[Abstract](10) [PDF 14892KB](2)
Abstract:
Additive manufacturing technology has great development prospects in the field of ship equipment manufacturing. The lightweight and low-loss manufacturing mode greatly improves energy and material utilization. However, due to the metallurgical characteristics of aluminum alloys and the additive manufacturing process, the aluminum alloy components are prone to metallurgical defects such as porosity and cracking in the additive manufacturing process, which seriously affects the quality, safety and reliability of ship equipment. In this study, we summarize the research status and progress of three main additive manufacturing processes (wire arc additive manufacturing, selective laser melting and additive friction stir-deposition) of ship aluminum alloys and the metallurgical defect control, and look forward to the future research direction of the additive manufacturing technology of ship aluminum alloys, so as to provide reference for the development of the additive manufacturing technology and defect control of ship aluminum alloy components.
Research and Discussion on Large-Scale Laser Powder Bed Fusion Metal Additive Manufacturing Equipment
CHENG Jinze, GUAN Kai, YANG Shuye, LIU Bin, JIANG Huanhuan
2024, 39(2): 28-36.
[Abstract](3) [PDF 8033KB](0)
Abstract:
The domestically-produced metal additive manufacturing processing equipment has been widely applied into the advanced research and development manufacturing field such as aerospace, military project, automotive, molds, and high-end medical care. As the demand for large-scale additive manufacturing gradually increases, overcoming the bottlenecks in the domestic production of large metal additive manufacturing equipment and process technology, and improving the manufacturing capabilities of the large-volume, high-quality metal parts in the additive manufacturing will play a significant role in alleviating challenges related to the forming range, process quality, and application segments of metal additive manufacturing. Combining the growing market demand for the large-scale metal additive manufacturing equipment and addressing the characteristics of laser powder bed fusion (LPBF) metal additive manufacturing equipment, we discuss the manufacturing of the large-scale and multi-beam equipment, as well as the cost and efficiency. Besides, we provide a brief introduction to the technical approach of super large-scale equipment with a "flying printing" structure.
Metallic Material
Effect of Deformation Temperature on Low∑CSL Grain Boundary Content of 06Cr23Ni13 Stainless Steel
YE Mengyuan, LI Junchen, QUAN Wei, LI Shanglin, DU Xiaoping
2024, 39(2): 37-43.
[Abstract](5) [PDF 6102KB](0)
Abstract:
The hot deformation behavior of the 06Cr23Ni13 stainless steel at different deformation temperatures and strain rates of 0.01 s-1 is studied by Gleeble-3500 instrument, and the effect of deformation temperature on grain boundary content of low coincidence lattice (CSL) is investigated. The results show that the recrystallization degree of the 06Cr23Ni13 stainless steel increases with the increase of deformation temperature. When the deformation temperature is 1 150 ℃, the recrystallization degree of microstructure is the highest, and the austenitic grain is equiaxed. According to the statistics of special grain boundaries of the 06Cr23Ni13 stainless steel under different deformation temperatureby Channel 5 software, the content of the low ∑CSL grain boundaries increases firstly and then decrease with the increase of the dynamic recrystallization degree during the hot deformation process, which reaches its maximum at 1 150 ℃. The low ∑CSL grain boundaries of the 06Cr23Ni13 stainless steel are mainly composed of ∑3, ∑9 and ∑27 grain boundaries.
Microstructure and Mechanical Characteristics of Rapidly Solidified AZ31 Magnesium Alloy
SUN Yuchu, CHEN Yungui
2024, 39(2): 44-49.
[Abstract](11) [PDF 15064KB](5)
Abstract:
AZ31 magnesium ribbons are prepared by the single roll rapid solidification method at different rolling speeds, and the microstructures are analyzed. The mechanical properties of AZ31 magnesium rods extruded at 250 ℃ from the ribbons are investigated. Results indicate that the rapid cooling directionally solidification region and gradual cooling equiaxed grain region are found in the cross-sections of the AZ31 magnesium ribbons, which is a thermal-gradient driven microstructure partition phenomenon. The heat insulation zone forms due to the gas entrapment in the melt pool, leading to the decline of microstructural homogeneity of the ribbons. It is found out that when the rolling speed is 17.58 m/s, the AZ31 magnesium rods extruded at 250 ℃ from the ribbons have the optimal performance, with the yield strength up to 360 MPa and the elongation up to 14.47 %.
Effect of Sensitization Treatment on Intergranular Corrosion Property of 825 Alloy
ZHANG Hengkun, LUO Xianfu, SHEN Pengyang, ZHANG Wenli, ZHA Xiaoqin
2024, 39(2): 50-56.
[Abstract](7) [PDF 8553KB](0)
Abstract:
The influence of sensitisation treatment on the intergranular corrosion properties of 825 alloy is investigated by 50 % sulphuric acid-iron sulphate intergranular corrosion test and polarisation curve analysis, and the causes are observed and analysed by metallography (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the corrosion rate and corrosion current density of the sensitized specimen of 825 alloy held at 750 ℃ for 1 h are 57 % and 48 % of those of the solid solution specimen, respectively. There are no precipitate precipitation at the grain boundaries of the sensitized and solid solution specimens, and no chromium-poor zones around the grain boundary, therefore, the material has no intergranular corrosion susceptibility. However, there are differences in potentials between the precipitated TiN and Ti(C,N) particles within the grains and the substrate, which can easily lead to the occurrence of pitting corrosion. After sensitisation treatment at 750 ℃ for 1 h, the grain size of the 825 alloy is uniform, the distribution of TiN and Ti(C,N) particles precipitated is uniform, and the corrosion resistance of the material is enchanced.
Study on Microstructure and Properties of A New Type of Sulfuric Acid and Hydrochloric Acid Corrosion-Resistant Cold Rolled Steel
YU Bo, ZHANG Yi, WU Hao
2024, 39(2): 57-62.
[Abstract](4) [PDF 8114KB](0)
Abstract:
A new type of corrosion-resistant cold rolled steel is taken as the object, and the effects of Mo and Sb elements on the microstructure, mechanical properties, and sulfuric acid and hydrochloric acid resistances of the steel are investigated. The results indicate that after adding Mo and Sb elements to the experimental steel, the ferrite grain size is only 6.24 μm, the yield strength is 384 MPa, the tensile strength is 459 MPa, and the elongation is 27.5 %. The mechanical properties can meet demands by regulates for the SPA-C steel. Besides, the corrosion rate of the experimental steel in the sulfuric acid medium is 0.14 mg/(cm2·h), and that in the hydrochloric acid medium is 0.31 mg/(cm2·h). The corrosion resistance of the experimental steel promotes by 10 times than that of the SPA-C steel.
Effect of Heat Treatment on Microstructure and Mechanical Properties of TiB95 Alloy Petroleum Pipes
XU Lingyu, MA Borong, LI Chong, SONG Dejun, CHEN Chunyang, SUN Xiaoyi
2024, 39(2): 63-67,88.
[Abstract](5) [PDF 6484KB](1)
Abstract:
In order to meet the demand for titanium alloy petroleum pipes under the harsh oil and gas exploitation environment, the TiB95 alloy is developed, which belongs to Al-Mo-Zr alloys. The effects of different heat treatment processes on the metallographic structure, mechanical properties and impact fracture morphologies of the TiB95 alloy petroleum pipes are studied by means of metallographic microscope, tensile testing machine, impact testing machine and scanning electron microscope. The results show that when the heat treatment temperature is 900 ℃, the TiB95 alloy petroleum pipes cooled at low rate (furnace cooling) have coarser structure, lower strength and higher toughness. When the cooling rate (air cooling) is the same, the α phase morphologies of the TiB95 alloy petroleum pipes heat treated at high temperature changes, the strength of the alloy reduces, and the elongation increases. The TiB95 alloy petroleum pipes with high strength and toughness can be obtained by using the 960 ℃,90 min,air cooling heat treatment process. The impact fracture surfaces of the TiB95 alloy petroleum pipes by different heat treatment processes are dimple morphology, which is ductile fracture.
Microstructure and Sintering Properties of Cu-10 % Sn Alloy Prepared by High-Energy Ball Milling
HE Qiumei, HOU Jianming
2024, 39(2): 68-74.
[Abstract](3) [PDF 11250KB](0)
Abstract:
The Cu-10 % Sn alloy powder is prepared by high-energy ball milling, and then it is cold pressed and sintered into bulk material. XRD and SEM are used to analyze the microstructure and property evolutions of the Cu-10 % Sn alloy during ball milling and sintering. The results indicate that Sn and Cu atoms combine to form a metastable Cu6Sn5 phase in the early stage of ball milling. The Cu6Sn5 decomposes again with the extension of ball milling time, and the decomposed Sn will be dissolved into the Cu lattice. After being milled for 40 h, the Cu-10 % Sn alloy powders form a single supersaturated solid solution with stable structure, and it transforms from a large thick lamellar structure to a fine, uniform and smooth surfaced granular structure. The average particle size is 30 μm, the grain size is about 26 nm, and the Sn and Cu elements are highly dispersed. The bulk material made from this ball milled powders has good comprehensive properties when sintered at 750 ℃. The metallurgical bonding between the powder particles is good, the bulk sample is basically stable, the open porosity is reasonable, and the microhardness is relatively high.
Feasibility Analysis on Powdery Emulsion Explosive in Explosive Welding of Aluminum-Steel and Titanium-Steel
JANG Xiaobo, LI Jun, HAN Gang, LIU Jintao
2024, 39(2): 75-80.
[Abstract](6) [PDF 1829KB](0)
Abstract:
The explosive welding of aluminum steel and titanium steel is carried out by using powdery emulsion explosive. The normal and high temperature shearing, normal and high temperature bonding, and lateral bending of the aluminum-steel and titanium-steel are investigated, and the interface morphologies including wave height, wavelength, and size of unwrapped compound at interface are analyzed. The application feasibility of powdery emulsion explosive in the explosive welding of aluminum-steel and titanium-steel is verified.
High Temperature Constitutive Equation Considering Strain Compensation of 12CrNi5MoV Forged Steel
HUANG Dong, WEI Mengfei, ZHANG Yuxiang, JIANG Ying, CHENG Bin
2024, 39(2): 81-88.
[Abstract](4) [PDF 7101KB](1)
Abstract:
The Gleeble-3500 thermal simulation tester is employed to investingate the thermal deformation behaviour of 12CrNi5MoV forged steel at deformation temperatures of 850-200 ℃ and strain rates of 0.1-0.001 s-1 by using a single-pass compression. The results show that dynamic recrystallisation occurs in 12CrNi5MoV forged steel at high temperatures and low strain rates, and that the recrystallisation doesn't or only partially occurs in 12CrNi5MoV forged steel at low temperatures and high strain rates. Based on the compression curve, the Arrhenius high-temperature principal model of 12CrNi5MoV forged steel is established, and its average relative error is 14.8 %; the Arrhenius high-temperature principal model of 12CrNi5MoV forged steel, which is established by taking strain compensation into consideration, has higher accuracy, with the average relative error 6.1 % and the correlation coefficient of 0.991.
Optimization of Hot Working Process for 10CrNi8MoV Steel based on Process￣ ing Map Technology
WAN Songlin, HUANG Dong, ZHANG Yuxiang, JIANG Ying
2024, 39(2): 89-94,118.
[Abstract](4) [PDF 11388KB](1)
Abstract:

High temperature compression test is carried out on the 10CrNi8MoV steel by using Gleeble-3500 thermo-mechanical simulator. The flow stresses of the 10CrNi8MoV steel under different temperatures, strain rates and strains are obtained, and its hot process map is established. The results indicate that the 10CrNi8MoV steel has two suitable hot deformation regions, which are the medium/high temperature and medium/low strain rate (1 020-1 100 ℃ deformation temperature and 0.001-0.1 s-1 strain rate) region, and the high temperature and high strain rate (1 150-1 200 ℃ deformation temperature and 3-10 s-1 strain rate) region. When the 10CrNi8MoV steel deforms in the above two regions, the microstructure is uniform and fine dynamically recrystallized grains are fine.
Nonmetallic Material
Self-Reporting and Self-Healing Dual Functional Anticorrosive Coating based on Tannic Acid Additives
MA Lingwei, YANG Xueting, ZHENG Kaining, WANG Jinke, WANG Yue, YANG Hao
2024, 39(2): 95-105.
[Abstract](4) [PDF 11501KB](0)
Abstract:
Tannic acid molecules are loaded into mesoporous silica nanoparticles (TA-MSNs) by one-step synthesis method to endow them with corrosion sensing and corrosion inhibition dual functions. TA-MSNs are added into the epoxy coatings to explore the self-reporting and self-healing performances of composite coatings. Firstly, the coloration and corrosion inhibition properties of TA are characterized. Then, the morphology and structure of TA-MSNs are investigated, and the release behaviors of TA from TA-MSNs studied. The influence of nanofiller content on the self-reporting and self-healing performances of coatings is comprehensively analyzed. Salt spray test indicates that the self-reporting effect of the coating is positively correlated with the filler content, and the addition of more than 5 %(w) TA-MSNs could give the coating obvious coloration effect. Electrochemical measurement and surface analysis show that the low-frequency impedance modulus (|Z|0.01 Hz) of the damaged coating with 5 % TA-MSNs is two orders of magnitude higher than that of the damaged blank epoxy coating. When the coating is damaged, TA molecules released in the coating can be complexed with Fe3+ formed during steel corrosion, resulting in blue-black coloration for corrosion reporting, and the complex adsorbed on the metal surface can form a protective film layer to inhibit further corrosion reaction. In summary, the epoxy coating with 5 % TA-MSNs possesses excellent self-reporting and self-healing performance.
Effect of Protective Coating on Solid Buoyancy Material under Hydrostatic Pressure
LIU Zhi, WANG Xiaojun
2024, 39(2): 106-110.
[Abstract](4) [PDF 6337KB](0)
Abstract:
Since buoyancy materials for submersibles often suffer from problems such as denting and cracking during the marine environmental tests after being coated with protective coatings, the all-round hydrostatic pressure resistance of buoyancy materials coated with different kinds of coatings is investigated. The results show that the type of coating has a small effect on the material. After wrapped the coating, the hydrostatic pressure resistance of the material decreases and the depth of the water used becomes shallower. The damage mechanism of the solid buoyancy materials with protective coatings under hydrostatic pressure is proposed.
Research on Hot Stamping Preparation Process and Joint Performance of 6061 Aluminum Alloy/Carbon Fiber Composite Plate
LIU Wang, TIAN Feng, WEI Jianhui, ZHU Bin, ZHOU Helezi, ZHOU Huamin
2024, 39(2): 111-118.
[Abstract](6) [PDF 6440KB](0)
Abstract:
Composite structural components play a vital role in the lightweight ships, and the stability of their joint performance is of great significance for the safety and transportation efficiency of the vessel. The application of the aluminum alloy and carbon fiber reinforced polymers (CFRP) composite materials in the manufacture of ship bulkheads, frames, and other structural components not only significantly reduces the weight but also enhances the overall strength, balances the overall toughness of the composite material, and exhibits high impact energy absorption capability. In order to explore the feasibility of stamping-bonding by hot stamping process for aluminum alloy and CFRP, using peeling test, the effects of different surface treatments for 6061 aluminum alloy, different holding time in stamping-bonding stage, and surface modification of prepreg materials on the properties of the aluminum alloy/CFRP composite joints are studied. The results show that the shear strengths of the joint after polishing, polishing and alkali cleaning, and polishing and acid cleaning on the surface of aluminum alloy are 2.50 MPa, 4.30 MPa and 4.60 MPa, respectively, which are 155.1 %, 338.8 % and 369.4 % higher than that of the untreated joint sample. In the stamping-bonding stage, when the holding time is less than 60 s, the joint shear strength increases rapidly to about 4.90 MPa. When the holding time is more than 60 s, the joint's shear strength decreases first, then increases slowly, and at last keeps stable in the range of 3.92 to 4.34 MPa. When the surface of the prepreg is sprayed with Graphene Oxide (GO), the shear strength of the joint is 5.98 MPa, which is 30.0 % higher than that of the joint with the prepreg untreated.

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