Steel Clad Plate Research Articles

The Impact of Surface Treatment and Degree of Vacuum on the Interface and Mechanical Properties of Stainless Steel Clad Plate.

In this study, the impact of different surface treatment and degree of vacuum on the interface and mechanical properties of 304/Q345 stainless steel clad plate was investigated. The study indicated that more continuous or aggregated Al2O3 and Si-Mn composite oxides were formed at the interface after brush grinding. However, less inclusions such as Al2O3, MnS and Ca-Mg-Al-Si composite oxides were formed at the interface after pickling treatment. For the vacuum degrees of 10−2 Pa, 1 Pa and 105 Pa, the oxidation reaction became more intense with the decrease in vacuum degree. The interface inclusions were gradually changed from Al2O3 and Si-Mn complex oxides to oxide scale and MnCr2O4 spinel oxide. The interfacial bonding strength of stainless steel clad plate was improved with the increase in degree of vacuum. The bonding strength was 55 MPa at vacuum of 105 Pa, but it was 484 MPa at vacuum of 10−2 Pa, which is far greater than that of the national standard, and an excellent performance was obtained.

Effect of Rolling Reduction Rate on the Microstructure of Hot Rolling Stainless Steel Clad Plate

The macro-scale and meso-scale simulation models of stainless steel clad plate were established by DEFORM-3D. The multi-scale coupling simulations of clad plate with different rolling parameters were carried out. The seven pass hot rolling process of stainless steel clad plate was simulated by numerical simulation. By contrasting the vertical stress and the deformation resistance of cladding layer, the rolling reduction rate satisfying interface bonding was obtained. The grain distribution at the center of the substrate layer was analyzed and reasonable hot rolling reduction rates were selected considering their effects on the recrystallization volume percent and the grain size. The results show that the grain size decreases with the increase of reduction rate. However, too much reduction rate will decrease the rate of recrystallization volume percent and the refining effect of grain is not obvious. To ensure uniform grain size distribution, it is most reasonable to set the rolling temperature to 1150°C and the reduction rate to 50%.

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.

Microstructure, mechanical properties and interface bonding mechanism of hot-rolled stainless steel clad plates at different rolling reduction ratios

The microstructure, interfacial characteristics, shear behavior, tensile properties and fracture morphologies of stainless steel clad plates fabricated by vacuum hot rolling at different rolling reduction ratios of 20%, 40%, 70%, 90% and 93.75% are investigated using optical microscope (OM), ultra-depth microscope, scanning electron microscope (SEM), electron probe microanalysis (EPMA) and universal testing in detail. With the increasing rolling reduction ratio, the refinement degree of microstructure is increased, while the thicknesses of interface alloy element diffusion zones including the decarburized, carburized layers and martensite zone are decreased. Due to the different interface bonding status, the shear fracture of clad plate rolled at a low reduction ratio of 40% is located at interface, while clad plates with high reduction ratios of 70% and 90% fracture at the decarburized layers. Therefore, interface shear strength is sharply and then slightly increased. Moreover, the interface bonding strength, tensile strength and interface deformation coordination are increased, while fracture elongation is increased firstly and then decreased with the increasing rolling reduction ratio, which are attributed to the competing mechanisms of grain refinement, work hardening, interface strengthening and intergranular cracks of carburized layer. Overall, the interfacial bonding mechanism can be related to the Mn-Si oxide inclusions rupture, alloying elements diffusion, phase transition and severe plastic deformation at high rolling temperature.

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 microscope 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.

Microstructures and properties of roll-bonded stainless /medium carbon steel clad plates

A 304 stainless steel/medium carbon steel clad plate was fabricated by hot-rolling in an argon atmosphere. The interfacial microstructures of the clad plates were observed by SEM, and the carbide phases were identified by XRD and TEM. The effect of the rolling parameters on the shear strength and composition diffusion was analyzed. The results show that a sensitization region appears in the stainless steel side and a decarburization region is present in the carbon steel side. The sensitization region is composed of a dual structure, ditch and full-depletion of chromium zones. The precipitates in the stainless steel side are Chromium-rich M23C6 carbides.

Microstructure and mechanical properties of hot rolled stainless steel clad plate by heat treatment

Series of stainless steel clad plates were heat treated at the quenching temperatures ranging from 900 °C to 1150 °C for holding time of 6min and 60min, respectively. It was observed that the ferrite and pearlite phases in the hot-rolled carbon steel substrate changed into lath martensite and needle-like ferrite through quenching treatment. The carburized layer thickness was gradually decreased till disappeared, and the interfacial shear strength was firstly increased and then decreased with the increasing quenching temperature, which was attributed to the sufficient alloy element diffusion and matrix softening at the high quenching temperature. At the quenching time of 6min, the shear fracture zone transmitted from the interface into the decarburized layer with the increasing quenching temperature, and the severe interfacial delamination cracks all existed at the clad interface. However, the main shear cracks were all presented at the decarburized layer for the quenching time of 60min, and there were no interfacial delamination cracks in the tensile samples, revealing that strong interface can be obtained by prolonging quenching time. The tensile behavior and fracture characteristics showed the ductile-brittle transition with the increasing quenching temperature.

Effect of heat treatment on the mechanical properties of copper clad steel plates

The mechanical properties anisotropy and heat treatment behavior of copper clad steel plates were investigated in detail. It was shown that the maximum yield strength and ultimate strength of copper clad steel plates are obtained along the tensile angle of 45°, whereas the minimum value of tensile ultimate strength (320.0 MPa) can be obtained at the tensile angle of 90°. The fracture region contains fibrous zone in the middle and the edge shear slip. The tensile ultimate strength and fracture elongation are gradually decreased with the increase of annealing temperature, which is attributed to the grain coarsening and interfacial delamination at high temperature. High residual compression stress is relieved at the annealing temperature, leading to low interfacial bonding state. There are no interfacial delamination cracks presented at all the cup drawing testing samples, all the fracture angles of raw clad plate and clad plates with annealing temperatures of 600 °C and 700 °C are almost 90° due to the mechanical anisotropy. However, due to disappearance of mechanical anisotropy of clad plate with annealing temperature of 800 °C, the fracture angle is far away from 90°.

Microstructural characterization of AA5183 aluminum clad AISI 1018 steel prepared by electro spark deposition

The application of a simple and effective technique, electro spark deposition (ESD), to create aluminum clad steel plate has been studied. AA5183 aluminum rods were used as the rotating electrode for cladding of the AISI 1018 steel. The microstructure of the interfacial zone including the intermetallic compounds (IMC) layer and the clad metal have been investigated by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM and STEM). According to the results sound aluminum clad with thickness up to 25–30 μm can be achieved. Very thin (<4 μm) IMC layer was formed at the Al/Fe interface and the structural (electron diffraction pattern) and chemical analysis (STEM) conducted by TEM confirmed that the layer is constituted of Fe rich phases, both implying a much improved mechanical properties. Investigation of the orientations of phases at the interfacial zone confirmed absence of any preferred orientation.

Magnetostrictive clad steel plates for high-performance vibration energy harvesting

Energy harvesting technology is becoming increasingly important with the appearance of the Internet of things. In this study, a magnetostrictive clad steel plate for harvesting vibration energy was proposed. It comprises a cold-rolled FeCo alloy and cold-rolled steel joined together by thermal diffusion bonding. The performances of the magnetostrictive FeCo clad steel plate and conventional FeCo plate cantilevers were compared under bending vibration; the results indicated that the clad steel plate construct exhibits high voltage and power output compared to a single-plate construct. Finite element analysis of the cantilevers under bending provided insights into the magnetic features of a clad steel plate, which is crucial for its high performance. For comparison, the experimental results of a commercial piezoelectric bimorph cantilever were also reported. In addition, the cold-rolled FeCo and Ni alloys were joined by thermal diffusion bonding, which exhibited outstanding energy harvesting performance. The larger the plate volume, the more the energy generated. The results of this study indicated not only a promising application for the magnetostrictive FeCo clad steel plate as an efficient energy harvester, related to small vibrations, but also the notable feasibility for the formation of integrated units to support high-power trains, automobiles, and electric vehicles.

Prediction of a High Temperature Bonding Condition at the Interface for the Hot-Rolled Stainless Steel Clad Plate on Rolling

The stainless steel-carbon steel clad plate was investigated using the theoretical analysis of various factors influencing the high-temperature interfacial bonding during its rolling. Phenomenological prediction analysis model of interfacial bonding strength at high temperature which considers the vacuum depth, rolling temperature, and rolling reduction, was established. The specific thermal simulation experiment was designed. The bonding strengths of carbon steel and stainless steel at 1000~1200°C and compression degree of 10~30% were measured by a Gleeble 3500 thermal simulator, as a result, the interfacial bonding ratio was obtained. The results show that the bonding ratio is 0.5–0.65 at the experimental temperature and compression degree. The numerical simulation method was used to analyze the influence of the compression degree of the first pass for a 2000 × 1500 × 100 mm stainless steel clad plate under the interfacial bonding conditions. The simulation results show that the optimum compression degree of the first pass is 15–20% at the rolling temperature of 1200°C.

Numerical Simulation and Experimental Study on the Interface Bonding of Stainless Steel Clad Plate

The rolling temperature and rate of thickness reduction directly affect the interface bonding quality,mechanical properties and microstructure of stainless steel clad plate. In order to obtain reasonable rolling process parameters, the multi-pass rolling processes of Q345R/316L stainless steel clad plate were simulated by the DEFORM software package. The distributions of stress, strain, and microstructure fields of the clad plate at different rolling temperatures and reduction rates were investigated. The bonding state of the interface was determined and the change rules governing the grain size of the rolled substrate layer also were analyzed. Vacuum hot-rolling tests were carried out to characterize the microstructure and mechanical properties. It was found that the higher the rolling temperature, the lower was the reduction rate needed to realize the interface bonding. However, too high temperatures produce a higher fraction of coarse grains, which affects the overall mechanical properties of the clad plate. It was concluded from the tests and numerical results that rolling temperature of 1150°C and reduction rate exceeding 50%, stainless allow one to produce steel clad plates with high interface bonding quality and excellent microstructure.

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 microstructure 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 °C 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.

Testing and Simulation of Vibration Energy Harvesting for Magnetostrictive Clad Steel Plates

Testing and Simulation of Vibration Energy Harvesting for Magnetostrictive Clad Steel Plates

Tensile shear sample design and interfacial shear strength of stainless steel clad plate

Tensile shear test is a suitable method to measure the interfacial bonding properties of stainless steel clad plates with thin cladding layer. Herein, three kinds of testing samples with different shapes (modes I, II and III) fractured at carbon steel substrate, stainless steel cladding, and interfacial zone, respectively. Interestingly, the tensile strength of carbon steel substrate (σbcs), stainless steel cladding (σbss), and the interfacial shear strength of stainless steel clad plate (τin) can be obtained from the three testing samples. The values of σbcs and σbsswere decreased, while τin was increased with the increasing rolling temperature, which were attributed to mechanisms of matrix softening and interface strengthening at high rolling temperatures. Moreover, under mode III, the shear fractures of clad plates rolled at 1375K and 1475K were located at interface and decarburized layer, respectively. The different fracture characteristics may be related to the sufficient carbon diffusion and interface toughening at a high rolling temperature.

Morphology of Intermetallic Compound and Interface Bonding State in Pure Al/Steel Clad Plates after 645°C/1h Diffusion Annealing

The correlation between intermetallic compound (IMC) and interface bonding state of the pure Al/08Al steel clad plate after 645°C/1h diffusion annealing was studied using the SEM. The results indicated that after 645°C/1h diffusion annealing for the pure Al/08Al steel clad plate, the IMC grew continuously along the interface with the thickness of 2-6 μm, while, at some regions grew abnormally with the thickness up to 10-30 μm. Moreover, some intrinsic defects at the interface, such as voids in the abnormally grown IMC and micro cracks along the interface were observed. The voids were possibly caused by huge difference of Al and Fe in diffusion coefficient, which is known as Kirkendall effect. On the other hand, the micro cracks could be attributed to the thermal stress during the cooling process because of larger difference of thermal expansion rate between Al and Al-Fe IMC. The intrinsic defects at the interface of Al/Steel could supply a novel way to correlate the morphology of IMC and interface bonding strength.

Mechanical bonding properties and interfacial morphologies of austenitic stainless steel clad plates

The current paper focuses on the correlation between microstructure and mechanical properties in low-carbon steel/austenitic stainless steel clad composite fabricated by hot-roll bonding. For this reason, the morphology and interfacial characteristics, tensile properties shear strength and fracture toughness of the cladded material were evaluated.From the main results, it was found that carbon element diffusion caused the forming of a decarburized ferrite zone (DFZ) of the parent metal and a carburized austenite zone (CAZ) of the clad layer, and between these two area, a thin diffusion layer with rapid element component change are formed in the hot-roll cladding process. Stress-strain curves obtained from tensile testing of parent metal and clad layer can predict the bi-material tensile behavior. The shear test proved that the stainless steel clad plate presents an acceptable shear bond strength at the interface joint. Impact test toughness results confirm that fracture took place only in the parent metal side of cladded specimens; the clad layer was bent but without obvious fracture. Fractography was carried out using scanning electron microscope in the tensile, shear bond test specimens and Charpy impact ones. It reveals the presence of predominantly dimpled fracture. Charpy impact specimens of the interface failed in mixed mode while impact specimens of the base plate failed in ductile mode.

Effects of laser-arc distance on corrosion behavior of single-pass hybrid welded stainless clad steel plate

Single pass laser-arc hybrid welding of stainless clad steel plate was first carried out to develop alternatives to multi-pass welding with low efficient or single pass welding with poor corrosion resistance. The results demonstrated that the weld corrosion resistance increased with the increase of laser-arc distance (DLA), and the corrosion morphologies changed from big and deep ‘nail’ pits to small and shallow hemispherical pits. The weld with nearly equal corrosion resistance to the base metal (BM) could be obtained at the DLA of 9mm, where the charge transfer resistance increased to 89% of the BM and the corrosion current density decreased by ten times to close to the BM, only 0.13μA·cm−2 lower. The corrosion resistance improvement had a good agreement with the microstructure homogenization and the increase of Cr content. The microstructure formation was discussed by the molten pool behavior and the laser-arc interaction. The corrosion resistance improvement was explained by the formation and damage mechanism of the passive film.

A Study on Stress Concentration Factor on Weld Toes of Cruciform Welded Joints with Misalignment by FEM Analysis

For the cruciform welded joints between corrugated bulkhead of duplex stainless steel plate and inner bottom of stainless (SUS) clad steel plate which have misalignment between the vertical steel plates under uniaxial and biaxial tensile loading conditions, numerical analysis of finite element method were performed with variable parameters of the loading condition, amount of misalignment, weld size and welding condition of penetration. The stress concentration factor on each weld toe of the cruciform welded joint was evaluated and the relations between the stress concentration factor and relative positional difference of weld toes on both side of inner bottom are investigated. As results, with misalignment, geometrical symmetry between weld leg shapes on both side of inner bottom is also desirable to avoid high stress concentration. In addition, for misalignment due to vertical alignment with mold line between vertical steel plates with difference in plate thicknesses, deep penetration welding is desirable to suppress stress concentration increased by its misalignment from comparison with fillet welding.

Comparison of the Effect of Different Heat Treatment Processes on Microstructure and Mechanical Properties of Stainless Steel Clad Plate

To improve the mechanical properties and corrosion resistance of 304/Q345R stainless steel clad plate, different heat treatment processes (oil cooling, oil cooling and tempering, oil cooling to 450°C as well as air cooling) have been performed after hot rolling. The microstructure, mechanical properties and corrosion resistance have been analyzed after conducting air cooling and heat treatment. The precipitated phases near the cladding interface have been measured using the energy spectrum analysis. The results imply that after hot rolling and air cooling the base layer microstructure is composed of ferrite and pearlite layers, while the overall strength of the clad plate remains to be low. The corrosion resistance is shown to be insignificant due to the higher precipitation of Cr carbide on the stainless steel side. After oil cooling, the hard phases of martensite and bainite dominate in the base layer microstructure. The plate strength has been enhanced, but its plasticity is insufficient. After tempering, the ductility value is considerably improved, however, it still fails to satisfy the requirements. After being oil cooled to 450°C and air cooled, the microstructure is found to be mainly composed of bainite, ferrite, and a small amount of pearlite. The clad plate mechanical properties, such as strength, plasticity as well as corrosion resistance, have been significantly enhanced.