Steel Clad Plate Research Articles

Investigation of Hot Rolling Influence on the Explosive-Welded Clad Plate

The microstructure, the shear strength and tensile strength of stainless steel explosive-welded clad plate at different rolling reduction were studied. The mechanical properties of the explosive-welded and explosive-rolled clad plates were experimentally measured. Simultaneously, the microstructures of the clad plate were investigated by the Ultra deep microscope and the tensile fracture surface were observed by the scan electron microscope (SEM). It was observed that the tensile strength has been increased considerably, whereas the elongation percentage has been reduced with the increase of hot rolling reduction. In the tensile shear test, the bond strength is higher than the strength of the ferritic stainless steel layer and meets the relevant known standard criterion. Microstructural evaluations showed that the grain of the stainless steel and steel refined with the increase of thickness reduction. Examination of the tensile fracture surfaces reveal that, after hot rolling, the fracture in the low alloy steel and ferritic stainless steel clad plates is of the ductile type. DOI: http://dx.doi.org/10.5755/j01.ms.22.4.12409

Influence of High-Temperature Ageing on Mechanical Properties of Low Alloy Steel Clad Plate Welded Joints

In this paper, the mechanical properties of welded joints of Q345R/304 stainless steel clad plates after high temperature ageing were studied. E309Nb welding rod, ER310 welding wire, and ER309L welding wire were used as cladding filling materials, and ER50-6 welding wire was used as base-layer filling material. The mechanical properties of welded joints were characterized by micro-hardness measurement and mechanics performance testing respectively, after ageing treatment at 600°C for 100 hours. Test results showed that there was lower carbon diffusion in the ER309L joint-base layer and transition layer than those of other two joints after high temperature ageing, and the hardness value had little change around ER309L joint-fusion zone. The microstructure of ER309L joint-fusion zone was different from that of other two joints. The impact test after high temperature ageing indicateed the impact toughness of three welding joints decreased obviously, and the weld zone of ER309L joint presented a worst toughness, which leded to the occurrence of brittle fracture.

Influence of High-Temperature Ageing on the Microstructure of Stainless Steel/Low Alloy Steel Clad Plate Welded Joints

This paper studies the microstructure of welded joints of Q345R/304 stainless steel clad plates after high temperature ageing. E309Nb welding rod, ER310 welding wire, and ER309L welding wire were used as cladding filling materials, and ER50-6 welding wire was used as base-layer filling material for welding. The metallographic microstructure of welding joints were studied after ageing treatment at 600°C for 100 hours. Test results showed that the microstructures of cladding weld zone were austenite and ferrite, and the ferrite in cladding weld zone of ER309L welded joints is less than the one in cladding weld zone of E309Nb and ER310 welded joints. The microstructure in the fusion zone is in-continuous, and the fine ferrite is distributed on the austenite matrix. After high temperature ageing, the width of fusion zone in ER309L welded joints is obviously less than that of the other two welded joints. The toughness of ER309L welded joints is better than that of E309Nb and ER310 welded joints.

The tensile behaviors and fracture characteristics of stainless steel clad plates with different interfacial status

The mechanical properties and fracture characteristics of stainless steel clad plates by vacuum hot rolling at different rolling temperature of 1100°C (S1), 1200°C (S2) and 1300°C (S3) are investigated in detail. The carburized layer thickness and grain size is gradually increased with the increasing rolling temperature. The sufficient alloy element diffusion, recovery and recrystallization at the bonding temperature of 1300°C lead to the highest interfacial shear strength and the lowest longitudinal tensile strength among the three clad plates. However, the tensile ductility is increased with the increasing rolling temperature, which is attributed to the increased interfacial bonding strength. The strong interface can effectively delay the formation of interfacial delamination crack and premature localized necking, resulting into a prolong uniform plastic deformation stage with a low stress triaxiality. In addition, there are many intergranular tunnel cracks with the length of 50–150µm presented in the carburized layer due to Cr23C6 carbides on the grain boundary, which can effectively toughen the stainless steel clad plates.

The Study on Degradation of Stainless Steel Clad Plate Used for a Shift Reactor in Coal Chemical Plant

Shift reactors are widely used in the petroleum and chemical industries, and especially in the coal chemical plants. The degradation of the reactor is critical to the safe operation of coal chemical plant. In this paper, a shift reactor after 8 year service was chosen. The test block taken from the reactor cylinder with the stainless steel clad plate was used and the test samples from the test block were prepared. And then, chemical composition analysis, metallographic examination, tensile and hardness tests were performed. The scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) method were used to study the degradation and degradation mechanism of the reactor. The metallographic analysis results show that there were a large number of carbides segregated in the grain boundary and the intergranular cracks were observed for the samples in the weld zone of the stainless steel clad plate. The SEM and EDS results indicate that the corrosion medium (i.e. polythionic acid) was found in the fracture surface of the samples from the weld zone of the stainless steel clad plate. The XRD test results show that the tensile residual stress occurred for the welding of the stainless steel clad plates. It is found that the degradation mechanism of the shift reactor was due to the polythionic acid stress corrosion cracking.

Heat-treatment of clad steel plate for application of hull structure

Clad steel plate has good corrosion resistance and mechanical properties arising from the hot rolling of dissimilar metals, such as carbon steel and stainless steel. However, it is difficult to simultaneously achieve good corrosion resistance from the cladding metal (stainless steel) and good mechanical properties from the base metal (carbon steel) because the different steels display opposite behaviours during the heat treatment process. Proper material selection and heat-treatment conditions are necessary for fabricating clad steel plates for application in the hulls of ships. In this study, the optimal heat-treatment conditions for maximizing the corrosion resistance of the metal (S32750) and the mechanical properties of the base metal (EH40) were investigated on the laboratory scale. The quenching and tempering method employing water quenching after treatment at 1080°C for 1h/in and air cooling after treatment at 550°C for ~1–2h was more effective than normalized heat treatment. The characteristics of the fabricated clad steel plate were evaluated using the selected heat treatment conditions.

Effect of interface oxides on shear properties of hot-rolled stainless steel clad plate

This paper aims at determine the effect of interface oxides on shear properties of 316L stainless steel/HSLA steel clad plate by studying interface microstructure, characteristics of interface oxides and shear fracture model. It was found that carbon element diffusion caused the forming of a decarburized ferrite zone (DFZ) of the substrate and a carburized austenite region (CAZ) of the clad metal, and between those two metals, a high-hardness band (HHB) with rapid element component change are formed in the solid-state diffusion bonding process. It was revealed that, at the micro-scale, when oxides concentrated area on the boundary of CAZ reaches up to a threshold size, DFZ crack may carve across the rigid HHB and propagate along CAZ boundary during the shear test. Thus macro-scale nonuniform distribution of oxides led to massive competitive cracking between the plastic DFZ and the high-strength CAZ, and statistically maintain the shear strength at a high level for test samples with a medium oxidation level. Nevertheless, those clad plates may still fail to meet the performance request of products, since the cladding interface tended toward a low fracture toughness failure during the process of deformation.

INVESTIGATION ON THE WELDING PROCESS AND MICROSTRUCTURE AND MECHANICAL PROPERTY OF BUTT JOINTS OF TA1/X65 CLAD PLATES

Titanium/steel clad material with excellent mechanical properties and corrosion resistance has important application in storage and transportation equipment of oil and gas. Due to the metallurgical incompatibility of titanium and steel, the mechanical properties of weld joint would completely lose when the brittle intermetallic phase TixFey and TiC appeared in the fusion welding process. Therefore, the gas tungsten arced welding (TIG), metal inert-gas welding (MIG) and metal active-gas welding (MAG) with V/Cu composite filler metals for butt joint in this study was carried out on TA1/X65 pipeline steel clad plates with thickness 16 mm ( titanium cladding with thickness 2 mm, X65 pipeline steel with thickness 14 mm). The microstructure, interface element distribution, main phase, microhardness distribution on cross section and mechanical properties of butt welds were investigated by using OM, XRD, EDS element mapping, microhardness and tensile test. The results indicate that the design of *国家高技术研究发展计划资助项目2013AA031303 收到初稿日期: 2015-11-30,收到修改稿日期: 2016-04-01 作者简介:毕宗岳,男, 1962年生,教授级高工,博士 DOI: 10.11900/0412.1961.2015.00615 第1017-1024页 pp.1017-1024

十字溶接継手止端部応力集中係数のFEM 解析による一考察

For the cruciform welded joints between corrugated bulkhead of Duplex stainless steel plate and inner bottom of stainless (SUS) clad steel plate under biaxial tensile loading condition, numerical analysis of finite element method were performed with changing the loading condition, fillet size and welding condition of penetration. The stress concentration on each weld toe of the cruciform welded joints was evaluated. As results, the geometrical symmetry between upper and lower side welded joint shape on inner bottom plate of cruciform welded joint is important to prevent high stress concentration under biaxial tensile loading condition and partial penetration weld is effective to suppress stress concentration from comparison with fillet weld.

Effect of Impact Pressure on Reducing the Weld Residual Stress by Water Jet Peening in Repair Weld to 304 Stainless Steel Clad Plate

Stainless steel clad plate manufactured by explosive bonding is widely used in the chemical industry, but cracks are often initiated in the clad layer. Repair welding is a popular method to repair the cracked zone. But residual stresses are generated inevitably, which can lead to further cracking. How to decrease the residual stress is critical to ensure the structure integrity. This paper studies a method to reduce weld residual stresses by water jet peening (WJP) in 304 stainless steel clad plate. The effect of impact pressure is discussed. A sequential coupling finite element method is developed to simulate the as-welded residual stresses, which is validated by impact indentation measurement. Then, a user subroutine is developed to model the moving load generated by WJP. The results show that the WJP can introduce compressive stresses on the metal surface and thus decrease the as-welded tensile stresses. As the maximum impact pressure at the center of impact (P0) increases, the residual stresses are decreased greatly and even change to compressive stresses. There is a critical value P0, which changes the tensile stresses to compressive stresses. As P0 increases to 1.4 times the yield strength of 304 stainless steel, the initial tensile stresses on the surface have been decreased to compressive stresses.

Study on the Local Mechanical Behavior and Forming Safety of the Clad Steel Plate Used in the Accumulator Tank of Nuclear Plant

The micro-morphology and local mechanical mechanic property parameters of the clad steel plates (304L+533B) used in the accumulator tank of nuclear plant at different temperatures are obtained from the microscopic and macroscopic test. And the monotonic tensile behavior of the clad steel plates and the forming process of the accumulator tank petals are simulated by using the finite element code ABAQUS. Based on the simulations, the validation of the obtained mechanical parameters and the forming safety of the clad steel plates are checked and evaluated. It is shown that the mechanical parameters obtained in this paper are reasonable, and the cold forming process of the rolling clad steel plates (304L+533B) used in the accumulator tank of nuclear plant is safe.

Development of the production technology for rolled clad steel plate

Development of the production technology for rolled clad steel plate

Roller Straightening Process and FEM Simulation for Stainless Steel Clad Plate

Based on elasto-plastic deformation straightening theory and by adopting 11 rolls straightening plates , the isothermal residual curvature straightening process was proposed for stainless steel clad plate. The mathematical model of straightening was established to realize plate shape finishing and stress reforming. By using finite element analysis software, establishing straightening process and determining intermesh, the effects of intermesh on shape and residual stress were analyzed. The results indicate that the straightening process met the finishing plainness of stainless steel clad plate after rolling. Longitudinal residual stress of the clad plate was evenly distributed across width. The cladding plate and steel substrate were observed to be symmetrical and the ascent of stress near the edge was greater. Longitudinal residual stress across length was distributed with the wave of pull-press-pull and the cladding plate and base plate were observed to be symmetrical. The above researches are based on the previous theory of the application of stainless steel clad plate straightening technology.

A novel reduction-bonding process to fabricate stainless steel clad plate

SUS304 stainless steel and plain carbon steel were successfully bonded by hot rolling after reduction descaling in pure hydrogen in this study. Shearing and peeling tests were performed according to the ASTM A264-03 standard and the ASTM D903-98 standard to evaluate the bond properties. The interfacial microstructures, composition diffusion and peel morphologies of the clad plate were obtained to study the effect of rolling parameters on bond interfaces. The experimental results indicate that the surface of plain carbon steel produces plenty of cracks and pores after reduction by hydrogen, the thickness of reduction layer is 7–8μm and the decarburized layer appears between the reduction layer and the substrate. The minimum shear strength and peel strength reaches 82MPa and 108N·mm−1 respectively at 1223K in the first pass with a deformation rate of 20.7%. The maximum shear strength and peel strength is up to 368MPa and 515N·mm−1 at 1323K after six rolling passes with an accumulated deformation rate of 74.5%. The maximum peel strength is greater than the strength of carbon steel substrate, and the shear strength and peel strength of clad plate vary directly as accumulative deformation rate and bonding temperature. Both the quantity and dimension of interfacial pores drop rapidly, and the bonding dimples become denser as the accumulative deformation rate increases. Embedment of some regions forms by the multiple passes hot rolling at the interface, and increases the interfacial bonding strength. An excellent reduction-bonding process can be employed to manufacture stainless steel clad plate.

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 ( $$ \dot{\varepsilon } $$ ), thickness ratio (k), and friction coefficient (μ) 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 Q235B, and the phenomenon of TA2 wrapping Q235B 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 $$ \dot{\varepsilon } $$ and μ and decreases when the metal flows along the contact area.

클래드강 맞대기 용접부의 후열처리 유지시간에 따른 델타 페라이트 거동

Recently, in order to enhance the function and usefulness of products, cladding of dissimilar materials that maximizes the performance of the material is being widely used in all areas of industry as an important process. Clad steel plate, produced by cladding stainless steel plate, an anticorrosive material, on carbon steel plate, is being used to produce pressure vessels. Stainless steel plate has good corrosion resistance, and carbon steel plate has good rigidity and strength; clad steel can satisfy all of these qualities at once. This study aims to find the <TEX>${\delta}$</TEX>-ferrite behavior, mechanical properties, structure change, integrity and reliability of clad steel weld on hot rolled steel plates. For this purpose, multi-layer welding, repair welding and post weld heat treatment were implemented according to welding procedure specifications (WPS). In order to observe the mechanical properties and toughness of clad steel weld zone, post weld heat treatment was carried out according to ASME Sec. VIII Div.1 UW-40 procedure for post weld heat treatment. With heat treatment at <TEX>$625^{\circ}C$</TEX>, the hold time was used as the process variable, increased by intervals that were doubled each time, from 80 to 1,280 min. The structure of weld part was typical cast structure; localized primary austenite areas appeared near central vermicular ferrite and fusion line. The heat affected zone showed rough austenite structure created by the weld heat input. Due to annealing effects of heat treatment, the mechanical properties (tensile strength, hardness, impact value) of the heat affected area tended to decrease. From the results of this study, it is possible to conclude the integrity of clad steel welds is not affected much in field welding, repair welding, multi-layer welding, post weld heat treatment, etc.

The preparation and property research of the stainless steel/iron scrap clad plate

As an attempt to recycle iron scraps, a new method is proposed to produce stainless steel clad plate by hot rolling. Iron scraps (Q195) were cold pressed into stainless steel pipe (304), and were subsequently hot rolled to produce composite clad plates at 1250°C. Experiments showed that the iron scraps could be compressed into solid steel and joined well with the outer stainless steel surface using the proposed method. The shear strength of the bimetallic interface formed is about 273MPa after seven pass rolling. The clad plates produced show good bending ductility. Element diffusion occurred at the interface during the hot rolling processes. The peak hardness appears in the vicinity of the interface due to the severe plastic deformation under high temperature and pressure during the rolling processes.

Interface Microstructure and Properties of 304 Austenite Stainless Steel/Low Carbon Steel Clad Plate by Casting and Hot Rolling Process

The 304 austenite stainless steel and low carbon steel clad plate was fabricated by casting and hot rolling process. The mechanical properties and interface shear strength of clad plates with different thickness after rolling were investigated in detail. The microstructure characteristics of the clad interface were observed by SEM (Scanning Electron Microscope). The phases and chemical composition were analyzed by XRD (X-ray diffraction) and EDS (energy dispersive spectroscopy). Based on the results, the mechanical properties and interface shear strengths meet the requirements of national standards. No visible cracks were observed in the clad interface after bending test. Cr3C2precipitates, Fe3O4oxides and Fe-Cr intermetallic compound were distributed around the interface of clad plate after casting, but a good metallurgical bonding was achieved after hot-rolling.

Interfacial microstructure and properties of a vacuum hot roll-bonded titanium-stainless steel clad plate with a niobium interlayer

Vacuum hot roll bonding (VHRB) was used to bond pure titanium (Ti) plate to a 304 stainless steel (SS) plate with a niobium (Nb) interlayer, with the aim of producing a high-quality Ti-SS clad plate. The roll-bonding process was performed at different temperatures in the range of 850–1000 °C, followed by characterization of microstructure and mechanical properties. The study demonstrates that the interfaces are free from cracks and discontinuities, and interdiffusion between the stainless steel and the titanium is effectively prevented by inserting a layer of pure Nb foil. No intermetallic reaction layer occurred at the Nb-Ti interface at any of the investigated temperatures. An intermetallic FeNb phase was formed at the Nb-SS interface when bonding was performed at 950 °C and above. The presence of the FeNb layer was confirmed by x-ray diffraction. The maximum shear strength of ∼396 MPa was obtained when bonding is carried out at 900 °C. However, the formation of the FeNb layer at roll bonding temperature greater than 900 °C led to decrease in shear strength. Ductile fracture occurred through the Ti-Nb interface for roll-bonded temperatures of up to 900 °C. On the other hand, at temperature of 950 °C and above, failure occurred through the Nb-SS interface, with brittle fracture characteristics.

Mechanical properties and sensitization on clad steel welding design

We have investigated the traits of clad metals in hot-rolled clad steel plates, including the sensitization and mechanical properties of STS 316 steel plate and carbon steel (A516), under various specific circumstances regarding post heat treatment, multilayered welds, and thick or repeated welds for repair. For evaluations, sectioned weldments and external surfaces were investigated to reveal the degree of sensitization by Micro Vickers hardness, tensile, and etching tests, and the results were compared with those of EPR tests. Clad steel plates were butt-welded using SAW + SMAW, and with the time of heat treatment as the variable, heat treatment was conducted at 625°C, for 80, 160, 320, 640, and 1280 minutes. Then, the change in corrosion resistance was evaluated in these specimens. With carbon steel (A516), as the heat treatment time increased, the annealing effect caused the tensile strength to decrease. The micro-hardness gradually increased and decreased after 640 min. The elongation and contraction of the area also increased gradually. The oxalic acid etch test and EPR test on STS316, a clad metal, showed STEP structure and no sensitization. From the test results on multi-layered and repair welds, it could be concluded that there is no effect on the corrosion resistance of clad metals. The purpose of this study was to suggest some considerations for developing on-site techniques to evaluate the sensitization of stainless steels.