Performance analysis of the SAW joint of duplex stainless steel clad plate

Duplex stainless steel clad plate exhibits good performance and is relatively inexpensive,however,some difficulties must be overcome when welding different materials. In this study,submerged arc welding（ SAW） was used to weld Baosteel ship clad plates（ 2205 ＋ DH36）,and the performance of the welded joints was tested. The results indicate that the mechanical properties and the corrosion resistance of the welded joints meet the required specifications. The distribution of the main anti-corrosive elements and the phase ratio of the welded joint are analyzed,thereby indicating excellent uniformity and confirming that the welded joint is corrosion resistant.

Interfacial microstructure and mechanical properties of stainless steel clad plate prepared by vacuum hot rolling

A stainless steel clad plate composed of stainless steel and carbon steel was prepared by vacuum hot rolling process, and its microstructure, especially the bonding interface, was evaluated using an optical microscope, a scanning electron micro- scope and a transmission electron microscope （TEM）. The corresponding mechanical properties were also assessed by means of hardness and shear tests. The results showed a bonding interface formed between stainless steel and carbon steel, which was relatively straight in macroscope but serrated in microscope. Decarburization layer and carbon-enriched layer were distinguished at the side of carbon steel and stainless steel near the interface, respectively, which should be related to diffusion of carbon and alloying elements. The carbon-enriched layer could also be identified as a recombination region, whose microstructure was mainly recognized as martensite by TEM. Consequently, the hardness was the highest at this region. Furthermore, the result of shear test at the bonding interface showed that the shear strength was 395 MPa and the fracture mode was dominated as ductile fracture, indicating the bonding interface with good quality.

Study on the interface of direct hot rolling titanium-clad steel plates

In this study,the interface characteristics of a direct hot rolling titanium-clad steel plate were analyzed, and the mechanism of interface cracking was explored. The detrimental effect from the formation of TiFe ,TiC,and a Si-enriched layer on the bonding strength was clarified, and an industrial-scaled titanium-clad steel plate with shear strength over 200 MPa was produced with a carefully set schedule accordingly. It was found that hot rolling titanium-clad steel plates had a flat interface without obvious cracks. In the rolling process,both Ti and Fe atoms interdiflhsed,but Fe difthsed much faster than Ti. The Fe-diffused area consisted of three regions. After a high temperature heat treatment, the diffusion depth of Fe and Ti elements increased significantly and evident Si segregation and TiFe layers were identified. Thermal cracking initiated in the Si segregation layer and then propagated along the TiFe layer and Fe-diffused layer on the titanium side.

Microstructure and properties of S30403+Q345R roll-bonded clad steel plate for pressure vessels

To meet the demand of the domestic pressure vessel industry for roll-bonded clad steel plates, Baosteel has developed an S30403 ＋ Q345R roll-bonded clad steel plate. Comprehensive inspections of the composition, microstructure, and properties are made to systematically evaluate the steel plate in the normalized and normalized ＋ stress relieved states. The results show the cladding interface of the S30403 ＋ Q345R roll-bonded clad steel plate has high shear strength, the base metal has good properties, and the mechanical properties of the steel plate head and tail are uniform. The performance is fully consistent with the technical requirements of the roll-bonded clad steel plate for pressure vessels.

Effect of Interlayers on Microstructure and Properties of 2205/Q235B Duplex Stainless Steel Clad Plate

In this research,2205/Q235 B clad plates were prepared by a vacuum hot rolling composite process.The effects of adding Fe,Ni,and Nb interlayers on the bonding interface structures and the shear strengths of the clad steel plates were studied.The results showed that 2205 duplex stainless steel and the three interlayers produced a large amount of plastic deformation and low-angle boundaries,and the main structures were the recrystallized and deformed grains.There were many recrystallized grains in the microstructure of the Q235 B low-carbon steel due to the low deformation in the rolling process.The Fe interlayer had better wettability with the two kinds of steel,but the lower strength led to the reduction of shear strength by about14 MPa compared with the original clad steel plate.The C element in the Q235 B low-carbon steel easily diffused into the Fe interlayer,and the clad steel plate attained a poor corrosion resistance because a large decarburization area was formed.The Nb interlayer reacted with the Mo element in the 2205 duplex stainless steel to form an Nb-Mo binary alloy,which generated long-banded ferrite.The decarburization area was also produced because the Nb reacted with the C element in the Q235 B to form hard and brittle NbCx.As a result,the shear strength was significantly reduced by about 282 MPa,and the corrosion resistance of the bonding surface was deteriorated.The Ni interlayer did not react with the alloy elements in both sides,and therefore effectively prevented element diffusion and improved the corrosion resistance of the bonding surface.Due to the low strength of the Ni interlayer and the increased number of bonding surfaces of the clad steel plates,the shear strength was reduced to some extent(about 40 MPa),but it still met the engineering application standards.

Development of SA-533 Type B CL. 1+SA-240 Type 304L roll-bonded clad steel plate for safety injection tank of CAP1400 nuclear power plant

Aiming to meet the demand of the country＇ s nuclear demonstration project on the CAP1400 nuclear power plant, Baosteel uses the roll-bonding technology and develops the SA-533 Type B CL. 1 ＋ SA-240 Type 304L high-strength and high-toughness clad steel plate with a shear strength of over 310 MPa for the nuclear power plant＇ s safety injection tank. The properties of the quenched and tempered and the simulated post-weld heat treatment states are systematically studied herein through a comprehensive inspection and evaluation of the composition,microstructure,and properties of the clad steel plate. The results show that the bonding interface has high shear strength and that the base metal has high strength and good toughness at low temperatures. Hence, the performance fully meets the technical requirements of the CAP1400 nuclear power plant＇ s safety injection tank in the country＇ s nuclear demonstration project. The roll-bonded clad steel plate can be used to manufacture the safety injection tank of the CAP1400 nuclear power plant.

Development of S11306+SA516Gr70 roll-bonded clad steel plate for pressure vessels

To meet the demand of the pressure vessel industry, Baosteel has developed an S11306 ＋ SA516Gr70 roll-bonded clad steel plate. Comprehensive inspections of the composition, microstructure, and properties are performed to systematically evaluate the steel plate in normalized state and normalized ＋ stress relieved state. The results show the cladding interface of the Sl1306 ＋ SA516Gr70 roll-bonded clad steel plate has high shear strength, and the base metal has good mechanical properties. The performance is fully consistent with the technical requirements of the roll-bonded clad steel plate for pressure vessels.

Industrial practice of clad-rolling in heavy steel plate production

In this paper,a brief introduction on clad-rolling heavy steel plates of 90 mm and 140 mm thick is presented.The steel plates were hot rolled by 265mm slabs that are cladded by double 135mm continuous casting slabs of Q235 steel.After hot rolling,interface of the cladding slabs completely disappeared, revealing uniform grains similar to the rest of the materials.Ultrasonic tests were carried out on both steel plates,demonstrating excellent results.Through thickness tensile tests were also implemented on both steel plates,resulting in perfect mechanical properties complying with specific standards.The result proves that a minimum reduction rate of 1.89 is available in producing 140 mm thick steel plate with excellent through thickness properties.

Gas metal arc welding of duplex stainless clad steel plates

The 2205 duplex stainless ＋ DH36 clad steel plate was welded by gas metal arc welding（GMAW）, and the welding performance of the clad steel plate was investigated. The results show that the adaptability of the welding procedure for the base metal of carbon steel, the transition layer, and the cladding material is excellent. The test results indicate that the phase proportion and component dilution of the GMAW-welded joints of clad steel plate can be effectively controlled to yield joints with good mechanical properties and corrosion resistance.

Overview of stainless-steel clad-plate welding

Types of bimetal clad plate, manufacturing methods, and their fields of application were summarized. In particular,key aspects of the welding of clad-rolled stainless steel were described, including the weldability of the base and clad metals, design criteria for the transition layer, the selection of the type of welding process and consumables used, types of blanking and welding bevels, preparation and assembly prior to welding, welding procedure requirements, post-weld cleaning and heat treatment, and welding quality inspection. This paper will serve as a reference for the welding technology used in future consumer applications in related fields.

Effect of vacuum level on microstructure and mechanical properties of titanium-steel vacuum roll clad plates

Vacuum roll cladding （VRC） was used to bond pure titanium （Ti） plate to a plain low carbon steel （Q345） with the aim of obtaining a high-quality Ti-steel clad plate. The effect of interfacial compound on the mierostructure and mechanical properties of Ti-steel clad plate was studied by electron probe microanalysis, scanning electron microscopy, X-ray diffraction and shear test. The clad plates were heated at 850 ℃ for 120 min and welded at different levels of vacuum. The results indicated that the cracked zone of the bonded interface decreased significantly with the increase in the level of vacuum during welding. Welding at atmospheric pressure, the randomly distributed TiN damaged the continuity of TiC and the uniformly diffused region of Ti and Fe at the bonded interface, while welding in vacuum of 1 × 10^-2 Pa, maximum shear strength of 298 MPa was obtained because of the decrease in TiN content.

送粉式激光增材制造工艺修复钛-不锈钢复合板的研究

为解决钛钢复合板制造和服役过程中产生的超标缺陷无法直接熔焊修复的难题,通过选择合适的中间层种类及厚度,分析了TA2/S30408复合板送粉式激光增材制造工艺的可行性。结果表明:相较于Cu-Ti梯度沉积层,纯铜层在沉积过程中裂纹萌生和扩展倾向更小,更适合作为钛-不锈钢复合板的中间层;中间纯铜层多次沉积且总厚度控制在1~1.2 mm时,可以在不降低复合板界面剪切强度的前提下,有效阻止不锈钢层中的Fe元素向钛层的扩散;TA2/S30408复合板各沉积层结合良好、无明显气孔裂纹等缺陷,剪切强度达标,有望利用送粉式激光增材制造工艺修复钛-不锈钢复合板。

不同真空度下轧制钛钢复合板的界面氧化行为

采用真空热轧复合技术制备了TA2/Q345R钛钢复合板,通过扫描电子显微镜(SEM)、维氏硬度计、万能拉伸试验机等分析了不同真空度下轧制钛钢复合板的界面组织和力学性能。结果表明:当复合坯真空度为1 Pa时,钛钢复合板钛复层氧化明显,TA2表面分别产生了10μm的富氧层与硬化层,硬化层硬度约为325 HV;当复合坯真空度为0.1 Pa时,TA2表面部分氧化导致钛钢界面产生约40μm厚的间隙,局部位置还产生了冶金结合;当复合坯真空度达到0.01 Pa时,钛钢复合界面平整连续无缺陷,平均剪切强度约179MPa。综上,0.01 Pa是轧制法制备钛钢复合板的合理真空度。

Manufacturing Technology and Application Trends of Titanium Clad Steel Plates

Some of the major manufacturing processes and corresponding mechanical properties of titanium clad steel plates were analyzed, and the consequences of research, manufacturing, and application of titanium clad steel plates in both markets of China and overseas were also summarized. As an economical and environmentally friendly technology, the roll bonding process is expected to become the next-generation mainstream process for the manufacturing of titanium clad steel plate. Some of the crucial and most important technical problems of this particular process, including vacuum sealing technology, surface treatment process technology, application of a transition layer, and rolling process, were discussed along with the advantageous mechanical properties and life-cycle economy of these plates processed by this technology. Finally, the market needs, application trends, and requirements of titanium clad steel plate were also considered from industries of petrochemical, shipbuilding, marine, and electric power.

压下率对304/高锰钢复合板组织与性能的影响

通过轧制压下率的变化研究了304不锈钢/高锰钢复合板界面组织结构、合金元素扩散及力学性能的变化规律。结果表明:304/高锰钢复合板界面两侧组织均为稳定的奥氏体,随压下率的增加,晶粒尺寸逐渐减小,且界面两侧晶粒尺寸差异减小。界面处存在大量的小角度晶界,通过细晶强化、晶界强化和位错强化机制提高了复合板结合强度及拉伸性能。此外,随着压下率的提高,元素的扩散层减薄,界面处存在的Al和Mn的氧化物及Cr的碳化物尺寸减小并弥散分布。随压下率提高,复合板界面得到强化,强度逐渐提高,伸长率逐渐降低。

High-temperature deformation behavior of titanium clad steel plate

In this paper, the single-pass hot compression experiment of titanium clad steel plate was carried out by Gleeble-3500 thermal mechanics simulation test machine,and the effect of deformation temperature(T), strain rate(ε),thickness ratio(k), and friction coefficient(l) on flow pattern of the metal and stress in the deformation zone was analyzed.The results show that the metal flow behavior and the stress during compressive deformation depend strongly on the deformation temperature. At 800 and 850 °C, the bimetal can flow uniformly, while at 900 °C, the TA2 flows faster than Q235 B, and the phenomenon of TA2 wrapping Q235 B is observed. The metal flow of the bimetal material will coordinate each other through the bonding interface. It is noted that the stress increases with the increase of the ε and l and decreases when the metal flows along the contact area.

Influence of pass reduction ratio on microstructure and properties of 2205/Q235B clad steel plate

2205/Q235B clad steel plates were fabricated using a thermal simulator.The metallographic microscope,scanning electron microscope,energy-dispersive spectrometer,shear test,electrochemical corrosion test and acid immersion test were used to study the influence of the pass reduction ratio on the microstructure and properties of 2205/Q235B clad steel plate.The results show that the clad steel plates had a good bonding surface when the pass reduction ratios were between 16.3%and 36.0%.There existed the mutual diffusion effect of elements near the bonding surface,which caused the long austenite strip on the side of 2205 stainless steel and the decarburization layer on the side of Q235B low-carbon steel.The transformation ofδferrite toγaustenite and the generation of the decarburization layer were promoted because of the lower pass reduction ratio.The corrosio n resista nee of 2205 duplex-phases stainless steel worse ned by the decrease in 8 ferrite con tent.The increase in the decarburization layer thickness made the shear strength of the clad steel plates reduce from 453 to 390 MPa.The potential of the decarburization layer was lower than that of 2205 stainless steel and Q235B low-carb on steel,which was easily corroded in the corrosive medium.

钛钢复合板在模拟海水中的表面耐蚀性能研究

采用极化曲线和交流阻抗测试方法,对比分析了爆炸钛钢复合板、增材制造钛钢复合板和去应力增材制造钛钢复合板在模拟海水的3.5%NaCl溶液中的表面耐蚀性能。研究结果表明,钛钢复合板表面钛覆层在3.5%的NaCl溶液中会发生电化学腐蚀,在电化学腐蚀过程中钛覆层表面生成1层稳定的氧化膜,提高其耐蚀性;增材制造复合板和去应力增材制造复合板的腐蚀电流密度和腐蚀速率均低于爆炸复合板,耐蚀性能更优;去应力退火能消除复合板内应力,提高增材制造复合板的耐蚀性能。

复合板固定管板热交换器设计中的几点探讨

复合板固定管板热交换器兼具高强度和耐腐蚀优点,在诸多行业中得到广泛应用。对复合板固定管板热交换器设计中的若干问题,如涉及复合管板相关事项、计算输入的简化及管孔结构的选择等进行了分析和探讨,论证了换热管承受轴向压应力时爆炸复合管板应用的可行性,点明了复合管板与换热管焊接连接拉脱应力计算中材料许用应力的取值误区,给出了SW6软件中壳程复层厚度的简化输入方式,阐明了复合管板与换热管连接方式的选择细节。可为复合板固定管板热交换器的设计提供有益参考。

热处理对316L/Q345R不锈钢复合板显微组织与力学性能的影响

依据不锈钢复合板双层金属特性,制定真空热轧成形316L/Q345R复合板热处理工艺为高温快速冷却+低温缓慢冷却。采用电子显微与能谱图分析分别对热处理前、后复合板试样进行显微组织特征观察和成分含量测定,研究复合界面显微组织、相结构和成分变化规律。采用剪切、拉伸及冲击功试验对两种状态试样进行力学性能测试,研究显微组织对力学性能的影响规律。结果表明:真空热轧后的复合板能较好复合,热轧试样中低合金钢侧组织为铁素体和珠光体,力学性能较差,不锈钢侧析出Cr的碳化物较多;经过热处理后,试样组织中有贝氏体出现,不锈钢侧Cr在加热制度下重新固溶。热处理实现复相化组织、合金元素界面扩散等复合组织结构的协同作用,从而大幅改善复合板的力学性能和耐腐蚀性能。