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.

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.

DRAWING OF ALUMINUM-CLAD STEEL WIRE BY FORCE-FEED LUBRICATION

The force feed lubrication method is used for drawing aluminum clad steel wire. It is studied how deformation of wire and aspect of the lubricant film are influenced by the die angle, the reduction, the drawing speed and the gap between pressure die and wire. It has been concluded that when the factors above mentioned promote to thicken lubricant film, the drawing force is reduced and this favors the homogenous deformation of aluminum coating and steel core.

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.

Effect of interface morphology on the mechanical properties of titanium clad steel plates

Interface morphology has important influence on the bond quality of titanium clad steel plates. The mechanical properties of titanium clad steel plates with wavy and straight interfaces were investigated by tensile-shear tests and bending tests. The interface morphology of the plates was examined by optical microscopy （OM） and scanning electron microscopy （SEM）. The experimental results show that the shear strength of a wavy interface is higher than that of a straight interface. A wavy interface is the guarantee for obtaining high shear strength to provide a greater shear resistance. During the maerobending process, cracks appear in the swirl of the wave tip and ferrotitanium intermetallies. For in-situ observing the bending process by SEM, the wave tip of a wavy interface and the massive ferrotitartium intermetallies of a straight interface are places where cracks initiate and propagate. The results are the same as those observed in the macrobending process. Became of high hardness, the wave tip and the massive ferrotitanium intermetallies are hard in terms of compatible deformation.

Interlayer engineering for titanium clad steel by hot roll bonding

Hot roll bonding was carried out between commercially pure titanium TA2 and high-strength low-alloy steel Q390 using pure Nb or Mo interlayer at 950 ~C with a total reduction ratio of 86.7%. Interfacial microstructure and bonding properties of titanium clad steel plates were investigated by electron microscopy and mechanical tests. The results showed β-Ti, TiC and Fe2Ti reaction phases were generated at Ti/steel interface for the clad plates with no interlayer. Inserting Nb or Mo interlayer can effectively suppress the formation of brittle phases, while the weak bonding joint transferred to Nb/steel or Mo/steel interface. And some micro-voids were found at the interface of Nb/steel and Mo/steel. The improved shear strength of clad plates with Nb interlayer might be attributed to the elimination of brittle phases at bonding interface. The small size and little quantities of the micro-voids at Nb/steel interface had a relatively weak effect on shear strength. However, the large number and big size of micro-voids were responsible for the degradation of shear strength for the clad plates with Mo interlayer.

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.

Development of a roll-bonded UNS N08825 alloy clad pipeline steel in Baosteel

In this study, a roll-bonded UNS N088225 alloy clad pipeline steel was investigated and developed in Baosteel. Based on the requirements of a number of potential projects, we performed a series of strict evaluations including mechanical and corrosion tests. The results show the mechanical properties and corrosion resistance of this clad steel to be excellent and to meet the requirements of all the design parameters.

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.

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.

Mechanical and corrosion properties of N08825 CRA clad pipeline steel

Corrosion-resistant-alloy(CRA)clad steel combines the good mechanical properties of the base material and the excellent corrosion resistance of the cladding material,while also being much more economical than solid CRAs.As gas and oil fields can have high concentrations of H2 S,Cl-,CO2,and other chemicals,the pipes used to transport gas or oil must have high corrosion resistance and good mechanical properties.UNS N08825 nickel-based alloys with their excellent corrosion resistance can be a good cladding material in clad steel.In this paper,UNS N08825+X65 clad steel was produced by two different processes.The thermomechanical and quenching and tempering processes were investigated and their mechanical properties and corrosion resistance were compared.Intergranular corrosion and pitting corrosion tests were conducted and the results were evaluated.A high-pressure and high-temperature gas-field environment was also simulated to test the stress corrosion cracking of the steel.The results show that both clad plates have good mechanical properties and excellent corrosion resistance.The experimental results were compared and the differences between the two processes were identified and discussed.

A STUDY OF CONTINUOUS EXTRUSION-CLADDING PROCESSFOR PRODUCTION OF ALUMINUM-CLADDING STEEL WIRE

In this study the process of cladding steel wires with aluminum is investigated experimentally. It is studied how the cladding process and the quality of products are influenced by the aluminum deformation temperature, the wheel speed, the temperature of steel wire, the wire speed and the steel wire tensile force. The relation among the process parameters above is discussed, and the effect of the aluminum deformation temperature on the coating microstructure is analyzed. This paper suggested a reasonable range of process parameters for producing aluminum cladding steel wires.

Wear and corrosion resistance of laser-cladded Fe-based composite coatings on AISI 4130 steel

The wear and corrosion resistance of Fe_（72.2）Cr_（16.8）Ni_（7.3）Mo_（1.6）Mn_（0.7）C_（0.2）Si_（1.2） and Fe_（77.3）Cr_（15.8）Ni_（3.9）Mo_（1.1）Mn_（0.5）C_（0.2）Si_（1.2） coatings laser-cladded on AISI 4130 steel were studied.The coatings possess excellent wear and corrosion resistance despite the absence of expensive yttrium,tungsten,and cobalt and very little molybdenum.The microstructure mainly consists of dendrites and eutectic phases,such as duplex（γ＋α）-Fe and the Fe–Cr（Ni）solid solution,confirmed via energy dispersive spectrometry and X-ray diffraction.The cladded Fe-based coatings have lower coefficients of friction,and narrower and shallower wear tracks than the substrate without the cladding,and the main wear mechanism is mild abrasive wear.Electrochemical test results suggest that the soft Fe_（72.2）Cr_（16.8）Ni_（7.3）Mo_（1.6）Mn_（0.7）C_（0.2）Si_（1.2） coating with high Cr and Ni concentrations has high passivation resistance,low corrosion current,and positive corrosion potential,providing a better protective barrier layer to the AISI 4130 steel against corrosion.

Microstructure and properties of pure iron/copper composite cladding layers on carbon steel

In the present study, pure iron/copper composite metal cladding was deposited onto carbon steel by tungsten inert gas welding. The study focused on interfacial morphological, microstructural, and mechanical analyses of the composite cladding layers. Iron liquid–solid-phase zones were formed at copper/steel and iron interfaces because of the melting of the steel substrate and iron. Iron concentrated in the copper cladding layer was observed to exhibit belt, globule, and dendrite morphologies. The appearance of iron-rich globules indicated the occurrence of liquid phase separation（LPS） prior to solidification, and iron-rich dendrites crystallized without the occurrence of LPS. The maximum microhardness of the iron/steel interface was lower than that of the copper/steel interface because of the diffusion of elemental carbon. All samples fractured in the cladding layers. Because of a relatively lower strength of the copper layer, a short plateau region appeared when shear movement was from copper to iron.

Characterization of Fe_3Si-based coatings on low silicon steel by pulsed Nd:YAG laser cladding

The Fe3Si based coating was produced on the Fe-1 Si steel surface by a pulsed Nd：YAG （yttrium aluminum garnet） laser. Its phase constitution and microstructure were characterized by using X-ray diffraction （XRD）, optical microscope （OM）, and field emission scanning electron microscope （FESEM） with associated energy dispersive spectroscopy （EDS） and transmission electron microscopy （TEM）. The hyperfine structure of the coating was studied by Mrssbauer spectra （MS） and the magnetic property was also measured at room temperature by a vibrating sample magnetometer （VSM）. The obtained coating is pore and crack-free with dense microstructure and high Si content. The metallurgical bonding between the coating and the substrate was realized. The microstructure of the coating is typical fine dendrites. The major phase was confirmed by XRD and TEM to be the ordering D03 structured Fe3Si phase. In addition, there were smaller amounts of the Fe5Si3 phase and the γ-Fe phase in the coating. Compared with the substrate, the laser cladding coating has a lower saturation magnetization and a higher coercive force. The poor magnetic property might be because of rapid solidification microstructure and phase constitution in the coating.

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.

Microstructure and corrosion resistance of 304 stainless steel electroslag strip cladding

The 304 stainless steel strips were deposited one layer on carbon steel base metal by electroslag strip cladding （ESC） and submerged arc cladding （SAC）, respectively. The solidification microstrueture of ESC metal was analyzed by the optical microscopy, scanning electron microscope and energy dispersive spectroscopy. The corrosion resistance studies of strip cladding metals were carried out in 10% oxalic acid electrolytic etching test. The results showed that the cladding metal obtained by ESC presented low content of C, high content of Cr and enough alloying element of Ni in the chemical composition. The transition zone of ESC with small width was almost parallel with the base metal, leading to a lower dilution. There are three types of solidification modes （ A→AF→FA ） occurred in the ESC metal due to the decrease of cooling rate and degree of dilution from the transition zone to the top of ESC metal. As a result, the microstructure of ESC metal exhibited mainly austenite with a small amount of ferrite, contributing to achievement of better corrosion resistance.

Pulsed Nd:YAG laser cladding of high silicon content coating on low silicon steel

A pulsed Nd：YAG （yttrium aluminum garnet） laser-based technique was employed to clad low silicon steel with preplaced Si and Fe mixed powders for high Si content. The surface morphology, microstructural evolution, phase composition, and Si distribution, within the obtained cladding coatings, were characterized by optical microscopy （OM）, field emission scanning electron microscopy （FE-SEM）, with associated energy dispersive spectroscopy （EDS）, transmission electron microscopy （TEM）, and X-ray diffraction （XRD）. The microhardness was also measured along the depth direction of the specimens, A crack- and pore-free cladding coating through excellent metallurgical bonding with the substrate was successfully prepared on low silicon steel by means of optimized single-track and multi-track laser cladding. The phases of the coating are a-Fe, T-Fe, and FeSi. The high microhardness of the lasercladding zone is considered as an increase in Si content and as the refined microstructure produced by the laser treatment. The Si contents of the cladding coatings were about 5.8wt% in the single-track cladding and 6.5wt% in the multi-track cladding, respectively.