DP600 Steel Research Articles

Process-based life cycle inventory framework for assessing the carbon footprint of products from complex production paths: Case of dual-phase automotive strip steel

The production paths of industrial products are usually complex, leading to difficulties and a large workload when conducting traditional process-based life cycle assessment (P-LCA). Existing studies on reducing LCA workload have focused mainly on simplifying the process or combining LCA with correlation methods. For complex production paths that cannot be simplified or changed, the methods have weak generality. To fill in these research gaps, a process-based life cycle inventory (P-LCI) framework for complex production paths is proposed. P-LCI contains accurate classification and definition methods for input, output and unit processes, and an interconnection model for calculating process coefficients according to the complexity of the linkages among processes is proposed. Based on the proposed framework, a case study of the dual-phase automotive strip steel (DP) production process is performed. The results show that the production of 1 kg of DP steel consumes 0.679 kg of molten steel from a basic oxygen furnace plant and 0.557 kg from the another. Coke plants produce the largest carbon footprint (CF) per unit of coke, which is 0.889–1.231 kgCO2e/kg-coke. For the cradle-to-gate lifecycle of DP steels, the BFP has the largest CF at 0.614 kgCO2e/kg-DP, accounting for 26.32%. Through the proposed P-LCI framework, unit processes can be clearly defined, and the interconnection model can be used as the basis for environmental impact analysis. When the production path changes, the model can be flexibly adjusted, and the workload of repeated model construction can be reduced.

Comparison of the Mechanical Properties and Approach to Numerical Modeling of Fiber-reinforced Composite, High-Strength Steel and Aluminum

The performance of carbon fiber reinforced polymer (CFRP) composite materials under quasi-static and high strain rate loading can be predicted with a high level of accuracy using the non-linear finite element analysis (FEA) method. Experimental validation tests under uniaxial tensile loading have shown a good correlation with FEA predictions for thermoset polymer composites, using commercially available epoxy resin MTM710 with carbon fiber reinforcement and for comparative tests on DP600 steel and aluminum alloys (AC170 and 5754 series). The physical and numerical results comparison of composite, aluminum, and high-strength steel indicates that the composite may be used as an alternative to aluminum and high-strength steel since the composite was shown to have almost the same strength as steel and higher strength than aluminum with the advantage of being lightweight and possessing similar mechanical behavior under quasi-static conditions. The results demonstrated that the strain rate range used did not significantly affect the strength of the composite materials. The selection of materials can be optimized reliably by FEA based on mechanical properties, cost, and weight. This will significantly reduce the new product introduction timescale, which is essential for the wider use of polymer composites for structural applications, especially in the automotive industry.

A physics-based plasticity study of the mechanism of inhomogeneous strain evolution in dual phase 600 steel

In this study, we employ a physics-based crystal plasticity finite element method (CPFEM) approach to study the microstructural response of DP600 steel to various loading types. With the pursued approach, it is possible link microstructural changes in the dual phase (DP) steel to its macroscopic response in a convenient and efficient manner. Microstructural data were acquired first from experimental work via the electron backscattered diffraction (EBSD) method. DP crystallographic features were then fed to a numerical hybrid calculation subroutine combining a comprehensive physics-based crystal plasticity scheme for ferrite along with an isotropic plasticity scheme for martensite defined on a single-layer representative volume element (RVE). The developed single-layer 3D mode, while allowing for high computational efficiency, can capture the stress/strain distribution, revealing the microscopic features of the deformation process including the physical evolution of the dislocation density, retexturing, and morphology. The single-layer RVE physics-based method employed herein establishes the strong correlation between morphology, dislocation density and deformation response of the material under various loading types. Specifically, findings reveal that the tendency of the ferrite phase neighboring the martensite regions in the DP steel to retexture is much more profound than pure ferrite when subjected to the same loading conditions, pointing out to the steep strain gradients in the former component. Martensite phase facilitates considerable heterogeneity in the stress and strain distribution, increases the misorientation polarization as well as leading to local strain hardening in the neighboring ferrite volume that stem from profound increase in spatial dislocation density. Stress-strain curves under various loading schemes are simulated and discussed in the light of the experimental findings in literature, revealing the dependence of the microstructural evolution on the loading type.

Role of martensite morphology on mechanical response of dual-phase steel produced by partial reversion from martensite

This work focused on the effects of martensite morphology on the mechanical properties of the dual phase (DP) steels produced via partial reversion from martensite, which is different from the traditional DP steels. A commercial DP780 steel was used, and the needle and blocky DP steels were produced by controlled heat-treatments. Combinations of SEM, EBSD and tensile tests were performed for understanding the property and damage mechanisms. The needle DP steel has higher ductility while lower strength than that of blocky DP steel. Much higher density micro-voids were uniformly formed in the needle DP steel than that of blocky case, and the coalescence of micro-voids into microcracks is strongly suppressed, due to the high-density ferrite/martensite interfaces and uniform local plastic strain. On the other hand, the blocky martensite islands distribution leads to the non-uniform local plastic strain, which caused the lower density micro-voids formation and the generation of micro-cracks, thus the resultant lower ductility. In addition, the higher strength of the blocky DP steel is due to strengthening of the sub-micron sized needle martensite.

Achieving high strength and high ductility of dual-phase steel via alternating lamellar microstructure

Overcoming the strength-plasticity trade-off in GPa-grade dual-phase steel while simultaneously enhancing both properties poses a significant challenge. In this study, we propose an innovative strategy to break this inherent dilemma by designing an alternately arranged ferrite and martensite lamellar microstructure with appreciable deformation coordination in dual-phase steel. Compared to traditional dual-phase steel (DP steel) with a block microstructure and the same phase components, the newly developed heterogeneous lamellar dual-phase steel (L-DP steel) prepared by a cyclic intercritical quenching process demonstrates a remarkable 90 % increase in uniform elongation (from 9.1 ± 0.4 % in DP steel to 17.3 ± 0.3 % in L-DP steel). The ultimate tensile strength increases slightly from 1002 ± 10 MPa (DP steel) to 1034 ± 11 MPa (L-DP steel). The lamellar martensite and lamellar ferrite with a certain hardness difference lead to high back stress during plastic deformation, thereby ensuring the ultra-high tensile strength of the L-DP steel. The improved ductility of the L-DP steel is primarily attributed to the appreciable coordinated deformation ability of the lamellar microstructure and the considerable plastic deformation ability of lamellar martensite. These two outstanding capabilities allow this unique microstructure to elongate continuously along the tensile direction, facilitating persistent work hardening without premature cracking. Furthermore, the heterogeneous hardening triggered by the mutual constraints of the lamellar microstructure during the plastic deformation also contributes additional work hardening to enhance the ductility. The design of lamellar microstructure under a cyclic intercritical quenching process presents an efficient and feasible pathway for producing GPa-grade dual-phase steel with considerable ductility.

Non-monotonic plasticity and fracture in DP1000: Stress-state, strain-rate and temperature influence

Recent studies revealed a complex, non-monotonic relationship between flow stress, and temperature and strain rate for ultra-fine-grained DP1000 steel, including unexpected drops in ductility. Consequently, a comprehensive investigation into the interrelated effects of temperature, strain rate, and stress state on the plasticity and fracture behaviour of DP1000 steel is undertaken. To this purpose, eight purpose-designed specimen geometries, including a shear, a dogbone, a central hole, and various notched samples, are tested at strain rates covering 7 orders of magnitude from the quasi-static over the intermediate to the dynamic regime and in a temperature range from -40 to 400 °C. The experimental design thereby provides 336 unique combinations of stress state, strain rate and temperature. The study reveals phenomena typically associated with dynamic strain aging (DSA), such as flow stress serrations, negative strain rate sensitivity, thermal hardening, and embrittlement. As a result, the present study provides a comprehensive overview of the plastic, damage, and fracture behaviour of DP1000 steel. It also offers unique insights into the influence of external loading conditions on DSA. Increasing strain rates and decreasing temperatures suppressed DSA and its effects. However, a novel and important finding is that the impact of stress state on DSA and, consequently, on the behaviour of DP1000 steel cannot be solely explained by stress triaxiality and Lode angle. Lower stress triaxialities and Lode angle parameters amplify the occurrence and severity of DSA manifestations. However, non-proportional stress states, high-stress gradients and relatively low maximum in-plane shear stresses are also identified as contributing factors.

Critical LME elongation: a criterion measured with Gleeble correlated to LME sensitivity during spot welding

Liquid metal embrittlement may appear on multiphase high strength galvanized steels during the spot-welding process. The aim of this paper is to describe a high temperature tensile test, performed with a Gleeble machine, to evaluate the LME sensitivity of a given coated steel in conditions similar to spot welding (time cycle). The critical LME elongation, corresponding to minimum of stress derivative during force decrease, has been found as being the most relevant parameter to measure the LME phenomenon. Relevant test parameters such as temperature, strain rate, applied thermal cycle, and effect of thermocouple welding have been studied on two steels. The first, TRIP 800 steel, presents a high sensitivity to LME between 750 °C and 900 °C while the second, DP600 steel, is not sensitive. Strain rate effect reveals a competition between LME crack propagation and ductile fracture. The study also shows the need to avoid welding thermocouple on Zn-coated side. Overall, the critical LME elongation from Gleeble test is well correlated to LME cracks number and depth in spot welding.

Achieving excellent properties of resistance spot welded 2GPa-grade press hardened steel and galvanized DP980 steel via double-pulse

Obtaining the excellent resistance spot welding (RSW) properties of press hardened steel is a challenge due to the high strength with 2GPa-grade. In this study, the microstructure, mechanical properties of the RSW weld in 2GPa-grade PHS and galvanized DP980 steel were investigated. During the single pulse welding, the coarse columnar martensite is generated in the fusion zone (FZ). The low peak load is 13.2 kN for tensile-shear (TS) loading and 3.4 kN for cross-tension (CT) loading and the corresponding failure energy is 6.5 J and 16.7 J, respectively. The fracture mode under two loading conditions is partial thickness-partial pullout (PT-PP) mode. To enhance mechanical properties, the suitable double pulse welding was applied. Compared with that of the single pulse weld, double pulse weld has three special zones in FZ: the Re-melted FZ with columnar martensite, the recrystallization zone (RX-zone) with equiaxed martensite and the tempering zone (T-zone) with tempered columnar martensite. The peak load under the TS and CT loading is significantly improved by 39 pct and 44 pct and the failure energy for TS loading is enhanced by 38 pct and 186 pct for CT loading, respectively. The failure mode changes from the PT-PP mode to the pullout failure (PF) mode for CT loading in double pulse welds.

Frictional behaviour of DP steel in sheet metal forming at Various temperatures

The Dual Phase steel can be found in a wide range of sectors, including the nuclear and pharmaceutical ones. Sheet metal forming is a highly prevalent production technique. Conversely, there has been a lack of understanding about the sheet metal forming of DP steel, especially with regard to friction, a crucial parameter to comprehend sheet metal forming precisely. In this work, the frictional properties of DP steel have been discovered to interface experimentally with Inconel 718, the most widely used superalloy for sheet metal forming products. 2 mm thick material was used in the investigation, and its effects were examined under various conditions including load and different angles.

Effect of strain rates on the forming properties of DP Steel at high-temperature

Dual Phase steel grade, with its remarkable combination of features including formability and resistance to high temperatures, has been a revolutionary alloy in modern industry. It is a useful material that may be applied to many different tasks. It presents us with the task of examining its characteristics in response to changes in critical parameters such as temperature and loading rate during stretching operations. Understanding the formability behavior of DP steel sheets, which have a thickness of 1 mm, at various increased temperatures and strain rates was the main goal of the investigation. We investigated and examined the tensile characteristics at 650 and 750 degrees Celsius in the first investigation. On the other hand, because of flow stresses in the material at higher temperatures, elongation has decreased in value as deformation rates have increased. In addition, we plotted the FLDs experimentally and examined the formation behavior while performing the Nakazima Test on specimens with a thickness of 1 mm. Furthermore, a limiting dome height (LDH) study was conducted on a laboratory scale. In terms of temperature, the LDH was shown to be higher at 750 and at 0.001/s

Determination of Modified Mohr-Coulomb Damage Model Parameters for DH780 Steel in Finite Element Analysis

In sheet metal forming processes, tearing problems might be occasionally encountered due to many reasons such as incorrect forming parameters. The trial and error methods that are used to solve such problems, on many occasions, are time-consuming and inefficient in terms of finding the correct forming parameters or die design for the forming process. The finite element analysis method, on the other hand, can be used as a tool that is both time and cost-saving. However, in order to effectively exploit the use of finite element analysis in sheet metal forming operations, the material that is used to be formed needs to be well characterized in terms of its hardening behaviour and failure criteria. In this study, a TRIP-aided DP steel (DH780) has been tensile tested in three different deformation conditions (uniaxial, plane stress and shear) and the parameters of its hardening model (Hollomon) and failure criteria (Modified Mohr-Coulomb) have been determined. According to the simulation results, obtained hardening parameters are able to describe the flow behaviour of the steel and the used failure criterion is able to predict the experimental failure correctly in each deformation condition.

Hydrogen Diffusion and Trapping Behaviour in DP Steels: An Electrochemical Hydrogen Permeation Study

Advanced high-strength steels (AHSSs) are widely used in the automotive industry as they possess high strength-to-weight ratio. This allows designing light vehicles with better passenger safety, lower fuel consumption, and CO2emissions. Dual-phase (DP) steels are very attractive among the AHSSs because of their optimal combination of high tensile strength (up to 1.2 GPa), high ductility (10 % or more), and good formability due to their two-phase microstructure (ferrite and martensite). However, the use of DP steel is associated with an increased risk of mechanical degradation in the presence of hydrogen environment, i.e., hydrogen embrittlement (HE). The HE susceptibility of DP steel is mainly determined by hydrogen entry, diffusion, and trapping events in the microstructure (i.e., hydrogen interaction with metal). There are various methods to study the above mechanism in metals like hydrogen charging-tensile test, thermal desorption spectroscopy, silver decoration, scanning kelvin probe microscopy, electrochemical hydrogen permeation, etc. Among these, electrochemical hydrogen permeation using Devanathan - Stachurski (DS) cell is a simple and most widely used technique.In this work, electrochemical hydrogen permeation was used to understand the role of microstructural features on hydrogen diffusion and trapping behaviour in DP-980 steel. It was identified that the phase fraction and its morphological features influence the hydrogen diffusion behaviour. The challenges in layout, design and integration of conventional DS cell into a tensometer and the effect of pre-strain (ex-situ) and tensile stress (in-situ) loading on hydrogen diffusion and trapping in DP-980 will be discussed. The applied elastic stress (i.e., 50 % of YS) during the permeation test resulted in a slight increase in Dapp from 5.4 ± 0.1 × 10- 7 to 5.9 ± 0.69×10-7 cm2s-1 and a slight reduction in NT from 1.08 ± 0.01 × 1021 to 1.0 ± 0.13× 1021 sites cm-3 compared to the no-stress condition. At 110 % of YS, the highest value of iss is 169 ±10.6 (µAcm-2) and a significant increase in the value of Capp to 3.6 ± 0.3 × 10-4 (molHcm-3 ), whereas no significant change in values of Dapp and NT were observed at 110 % YS compared to no stress and 50 % of YS. This could be due to the elastic deformation of martensite at 110 % of YS. The lattice expansion of martensite under elastic tensile stress can accommodate more interstitial hydrogen, thereby higher steady-state permeation current is observed. At 125 % of YS, the value of Dapp (2.86×10-7 cm2s-1) is approximately 50 % less compared to the value observed for the un-stressed specimen (5.4 ± 0.1×10-7 cm2s- 1). The value of NT (2.11×1021 cm-3) is approximately two times higher than that of the value (1.08×1021 cm-3 ). Plastic deformation of both ferrite and martensite results in increased dislocation density (hydrogen trap sites) at 125 % of YS. The sample failed during the hydrogen permeation test and when it is subjected to 125 % YS. It exhibited distinct fractographic features along the thickness of the sample. Quasi-cleavage and intergranular cracks were observed near the cathodic surface. Whereas, dimples and microvoids which are complete ductile features, were observed near the anodic surface. At 125 % of YS a significant decrease in the value of DL 0.6×10-6 cm2s-1 was observed. Whereas the value of NTrev increased to 4.0 ± 0.2×1019 cm-3 from 3.0 ± 0.15×1019 cm-3.An attempt was made to study the hydrogen transport behaviour at the local spot by appropriate modification of conventional DS cell. The fabrication challenges and the potential application of such an instrument will be elucidated.

Semi in-situ investigations on deformation-induced micro-damage in high-strength dual-phase steels

This work investigates deformation-induced micro-damage modes in ferrite-martensite dual-phase (DP) steels utilizing a state-of-the-art semi in-situ deformation apparatus integrated with scanning electron microscope. By integrating secondary electron imaging, electron backscatter diffraction, and electron channeling contrast, we provide comprehensive statistical results on micro-damages and strain localization events of their formation in DP780 and DP980 steels. The current observations indicate that interface decohesion plays a critical role in DP780, particularly under plastic instability. Based on maps of Kernel averaged misorientation, interface decohesion arises from the accumulation of geometrically necessary dislocations, which serve to compensate for the deformation incompatibility between ferrite and martensite. In contrast, the dominant damage mode in DP980 under plastic instability involves ferrite cracking within martensite-surrounded ferritic grains. This type of micro-damage is a result of strain localization by shear bands that accommodate the global deformation while the grain is constrained by martensite islands. Martensite cracking does not show as predominate sites under the condition of plastic instability in both steels. In summary, our findings highlight the importance of deformation incompatibility and constraint on occurrence of micro-damages through distinct strain localization events, which are determined by both microstructure of damage site and its environmental microstructure. In this work, we shed light on the role of microstructural engineering as a critical strategy for enhancing the resistance of DP steels or hetero-phase steels against deformation-induced damage.

The Influence of Springing of High-Strength Steel DP780 on the Limiting Possibilities of its Forming during Electro-Hydraulic Stamping

Using the example of stamping a box-shaped part from high-strength sheet steel by a pulsed electro-hydraulic method, the limiting possibilities of its shaping, taking into account the springing of the material, are studied. The influence of the radius of the curvature and the shape of the surface of the corners of the part on the change in the structure of high-strength steel DP780 and the appearance of defects in it is determined. Relations between the radius of the curvature of the surface of the part and the thickness of the workpiece are obtained, at which there are no defects in the structure of DP780 steel and the limiting possibilities of its deformation are achieved with minimal springing of the material.

Study on the Micro-Texture and Anisotropy of a Cold-Rolled and Intercritically Annealed DP800 Steel

Study on the Micro-Texture and Anisotropy of a Cold-Rolled and Intercritically Annealed DP800 Steel

Influence of Temperature on the Forming Limits of High-Strength Low Alloy, and Dual-Phase Steels

High-strength steels (HSS) appear as a good alternative to common steels to reduce vehicle weight, thus reducing fuel consumption. Despite the excellent mechanical behavior towards its lower weight, its application in industry is still limited, as manufacturing such materials suffers from limitations, especially regarding formability. The literature shows springback to be the most common problem. Among the parameters that can be studied to minimize this problem, the temperature appears, according to the literature, to be one of the most influential parameters in minimizing springback. However, the consequence of the temperature increase on the forming limits of materials is not completely understood. This study proposes to determine the consequences of the use of the temperature rise technique in the forming limits of high-strength steels. Two different steels were studied (HSLA 350/440 and DP 350/600). To evaluate the formability, the Nakazima method was used (practical). Finite element models were made which describe the material as well as Nakazima experimental behavior. To predict the forming limit strains via the numerical method, the thickness gradient criterion was applied. The practical and computational results were compared to validate the finite element model. Four different temperature ranges were analyzed. In general, it was found that 400 °C has a negative impact on the forming limits of both steels. This negative effect was found to be due to the alloying elements, such as silicon and manganese, present in the alloy. These alloying elements take part in the increase and decrease in resistance coefficient at the elevated temperature. For HSLA 350/440 steel, the forming limit strain decreased with an increase in temperature up to 600 °C and then increased at 800 °C; whereas for DP 350/600 steel, the forming limit strain decreased till 400 °C and then increased for 600 °C and 800 °C. Another factor which might have contributed to the behavior of the DP steel is the interaction of hard martensite with soft ferrite phase.

Effect of a Zn interlayer on the formation mechanism and mechanical performance of AA6061/DP590 steel resistance riveting welding

This study focuses on the forming mechanism of resistance riveting welding joints of 6061 Al alloy and DP590 steel plate and the effect of adding Zn interlayer on the mechanical properties of the joints. During the piercing stage, the rivet pierces through the Al plate, the Al plate beneath the rivet melts and reacts with the steel, with intermetallic compounds (IMC) generated. Some of the melted Al and IMCs are squeezed onto the side of the rivet. In the process of adding the Zn interlayer, the Zn is gradually incorporated into the melted Al near the rivet during the piercing process. At the welding stage, as the current is increased, the nugget diameter, peak joint load, and energy absorption values gradually increase. The failure mode of the joint changes from an interfacial fracture to pull-out fracture, eventually changing to base material pull-off, as the welding current increases. Compared to joints without Zn addition, joints with Zn addition exhibit a smaller nugget diameter, and narrower IMC layers at the interface. At a welding current of 13 kA, because the failure mode was a shear fracture of the nuggets, the peak joint load of the joints with zinc added decreased by 215 N compared to the unadded ones. On the contrary, when the current increased to 14 kA, the peak joint load of the joints was elevated by 639 N, because the IMC layer and the aluminum plate became the main load-bearing locations.

Semi-automatic miniature specimen testing method to characterize the plasticity and fracture properties of metals

Miniature-testing is essential to characterize the plastic response of materials for which the extraction of conventional full-size specimens is impossible. Examples are weld regions with high property gradients or electronic circuit components. Here, we present the design of a novel testing system for miniature specimens. After inserting the specimens with wedge-shaped shoulders, the system carries out the clamping, initial geometry scanning, and mechanical testing with digital image correlation in an automated manner. The automation prevents the accidental damaging of the miniature specimens during manual handling and adds to the robustness of the overall procedure. It is shown that the experiments with miniature specimens extracted from DP600 steel and aluminum 7075-T6 are highly reproduceable. More importantly, they lead to the same plasticity and fracture properties as experiments on conventional ten-times larger full-size specimens. A correction procedure accounting for the surface roughness, white layer and heat affect zone induced through wire EDM is provided. In addition to developing and validating the new experimental technique, it is applied to characterize a 22MnB4 rod material and stainless steel 316 L foil.

Effect of compressive load on texture evolution and anisotropic behavior of dual-phase steel under biaxial loading in complete σ11-σ22 space

Advanced high strength steels (AHSS) are typically loaded in a multiaxial stress state during forming process and service. However, the deformation mechanism under multiaxial loading is not clarified, which limits the optimization of sheet metal forming. In particular, due to instability, biaxial compression loading of single thin plate has not been reported, which results in unclear evolution of the yield surfaces in the second, third and fourth quadrants of σ11-σ22 space and corresponding deformation mechanisms. Therefore, the deformation mechanism of AHSS thin plates under biaxial loading was systematically investigated in the complete σ11-σ22 space using a specially designed cruciform specimen and buckling prevention fixture in the current work. The mechanical properties of dual-phase (DP780) steel under different loading paths were studied by uniaxial tension, uniaxial compression, and biaxial loading tests. There is an obvious yield strength difference between the first quadrant and the third quadrant in the σ11-σ22 space. In the second and fourth quadrants of σ11-σ22 space, the compression part makes a greater effect on the yield behavior of the material than the tension part. More specifically, dislocation slip is activated earlier at the boundary under compression loading, resulting in earlier yielding of the material. Based on the analysis of the Taylor factor, the activation of slip systems of DP780 steel before and after deformation is clarified. In addition, a detailed analysis of the microstructure and texture evolution in DP780 steel after deformation is conducted, and a correlation between texture evolution and loading paths is established. It is found that the compression part under biaxial loading results in more grains with low Taylor factor and promotes the transformation of the initial texture to copper or rotated copper texture in DP780 steel.

A comparative study of microstructure and corrosion resistance in DP980 steel joints under different laser welding method

Three different laser welding methods were used to welding 2 mm DP980 steel butt joint, which were laser welding, laser-TIG hybrid welding and laser powder feeding (CoCrNi) welding respectively. An observational analysis was carried out in terms of microstructure, mechanical properties and corrosion resistance. It was discovered that a central microstructure of laser welding and laser-TIG hybrid welding the weld was dominated by slatted martensite. The laser powder feeding welding has resulted in a remarkable reduction of cylindrical crystals and an increased number of isometric crystals in weld center due to the addition of CoCrNi powder. Microstructure was further refined in incomplete phase transition zone by three different laser welding methods. The tempered martensite was also formed in the tempering zone, which softened the joint. The hardness values decreased considerably and tensile samples were also fractured at this location. Comparison with corrosion resistance of their joints through polarization curves and impedance spectra shows that laser powder feeding joint > laser joint > laser-TIG hybrid joint. The corrosion resistance of laser and laser-TIG hybrid joints in the base metal (BM) > heat affected zone (HAZ) > weld zone (WZ) is shown based on scanning vibrating electrode technique (SVET) localized area testing data at different time intervals. The laser powder feeding welding enhances the density of passivation film by reacting Cr to form Cr2O3, thereby improving corrosion resistance of entire joint.