Mechanical and metallurgical properties of friction welded AISI 304 austenitic stainless steel

Owing to the superior properties, of stainless steel it is pertinent to make use of it in various automotive, aerospace, nuclear, chemical and cryogenic applications. It is observed that a wide range of dissimilar materials can be easily integrated by solid phase bonding techniques, such as friction welding and explosive bonding. This study mainly focuses on friction welding of AISI 304 austenitic stainless steel. The friction processed joints are evaluated for their integrity and quality aspects. Friction welding of austenitic stainless steel was carried out using a KUKA friction welding machine (Germany). As the friction time increased, the fully plastically deformed zone (region I) in the vicinity of the bond line becomes increased. In contrast, an increase in friction time will decrease the region (region II) where the grains are partly deformed and grown. Tensile test results indicated that, the joint strength is decreased with an increase of the friction time. The detailed fractographic observation confirmed that the rupture occurred mostly at the joint zone and partly through the base material.     

Effect of friction welding parameters on mechanical and metallurgical properties of ferritic stainless steel

Friction welding is one of the most economical and highly productive methods in joining similar and dissimilar metals. It is widely used in the automotive and aerospace industrial applications. Ferritic stainless steel (AISI430) is normally difficult to weld by fusion methods, due to the associated problems such as grain growth and retained austenite content. Such problems can be alleviated by the friction joining process. The present study utilized a continuous drive friction welding machine to join cylindrical specimens of ferritic stainless steel of similar composition and shape (equal diameter and length). The processing parameters such as friction pressure, friction time, upsetting pressure and upsetting time were changed in order to understand the role of parameters on the strength related aspects of friction processed joints. The joints were subjected to mechanical testing methods such as the uni-axial tension test, and charpy ‘v’ notch impact tests. The micro hardness variation across the joint zone was determined. Micro structural studies were also carried out. The characteristics such as tensile strength, toughness and microstructural aspects exhibited by friction processed joints were compared to parent materials.     

Tensile properties and microstructural features of 304L austenitic stainless steel produced by wire-and-arc additive manufacturing

The International Journal of Advanced Manufacturing Technology - Additive manufacturing (AM) has gained great importance in the recent development to produce metallic structural elements for civil...     

Optimization in thermal friction drilling for SUS 304 stainless steel

The main purpose of this research is to develop a new type of thermal friction drill made of sintered carbide. In addition, to optimize the machining process of the thermal friction drilling using Taguchi method is explored. The experiments were conducted on a 30?×?30?×?2?mm SUS 304 stainless steel plate. The effects of friction angles (FA), friction contact area ratio (FCAR), feed rate (FR), and spindle speed (SS) on the two quality characteristics, surface roughness (SR) and bushing length (BL), were also investigated. After conducting all the experimental trials, the analysis procedure followed. Firstly, the significance of the four parameters on the two quality characteristics was examined by ANOVA. Then the optimal combination levels of parameters for SR and BL were determined based on the S/N ratios. Finally, confirmation experiments were conducted to verify the experimental findings. Results showed that FA and SS were the significant machining parameters that most intensively affect SR while FCAR was the only significant parameter for BL. Specially, the SR and BL were greatly improved when used in the optimized parameters settings. More importantly, the performance of the friction drill was conducted 60 runs. The thermal friction drill demonstrated a smoother, mirror-like surface and showed less wear. This proved that thermal friction drilling provided the better machining performance and longer tool life.     

Experimental investigation of the effect of vibration on mechanical properties of 304 stainless steel welded parts

Some of the problems that occur during the welding process include the creation of coarse grains in the weld structure and the hardening of the weld region, which reduce the strength and impact resistance of the welded parts. One technique to improve the mechanical properties of weld is the application of mechanical vibration to the molten pool. In this article, the effect of vibrating the part during welding on the mechanical properties of steel plates has been investigated in the tungsten inert gas (TIG) welding process. The plate is made of stainless steel 304 with 2 mm in thickness. A filler material has also been used for welding so that the effect of vibration can be observed on the weld pool region. The experimental tests have been performed under different welding conditions with respect to voltage, current, welding speed, vibrations amplitude, and frequency. Then, the resultant mechanical properties of the tested parts were measured. Also, the microstructure obtained by applying the vibration has been examined. Based on these experimental results, the effect of mechanical vibration on mechanical properties of the weld was investigated. Moreover, considering the mechanical properties obtained from these experiments, the optimum values of amplitude, frequency, and welding speed were determined.     

Thermal modeling of friction stir welding of stainless steel 304L

This paper presents a numerical model, based on the displacement of one point of the material flow relative to a fixed reference point, in order to formulate the heat generation during friction stir process and thereby calculate the temperature difference between advancing and retreating sides. This model considers frictional heating dependent on both the temperature and the velocity of the tool, as well as heat generation due to plastic deformation dependent on temperature, and assumes that friction heat at high temperature was replaced by heat generation due to plastic deformation. The heat generated by plastic strain energy dissipation in thermomechanically affected zone is calculated by a new technique, and the convection heat transfer coefficient and the sticking state parameter are considered as a function of temperature. Finally, the thermal equations are solved using a nonlinear finite element code ABAQUS. The numerical results correctly showed the asymmetric nature of temperature distributed at different sides of the weld line which have good agreement with experimental data that are presented in the literature.     

Effects of laser shock processing on mechanical properties of laser welded ANSI 304 stainless steel joint

With the rapid development of engineering component with integration,high-speed and multi-parameter,traditional techniques haven’t met practical needs in extreme service environment.Laser welding,a new welding technology,has been widely used.However,it would generate the drop of mechanical properties for laser welded joint due to its thermal effect.Laser shock processing(LSP) is one of the most effective methods to improve the mechanical properties of laser welded ANSI 304 stainless steel joint.In this paper,the effects of LSP on the mechanical properties of laser welded ANSI 304 stainless steel joint have been investigated.The welded joint on the front of the tensile samples is treated by LSP impacts,and the overlapping rate of the laser spot is 50%.The tensile test of the laser welded joint with and without LSP impacts is carried out,and the fracture morphology of the tensile samples is analyzed by scanning electron microscope(SEM).Compared with the yield strength of 11.70 kN,the tensile strength of 37.66 kN,the yield-to-tensile strength ratio of 0.310 7,the elongation of 25.20%,the area reduction of 32.68% and the elastic modulus of 13 063.876 MPa,the corresponding values after LSP impacts are 14.25 kN,38.74 kN,0.367 8,26.58%,42.29% and 14 754.394 MPa,respectively.Through LSP impacts,the increasing ratio of the yield strength and tensile strength are 121.79% and 102.87%,respectively;the elongation and area reduction are improved by 5.48% and 29.38%,respectively.By comparing with coarse fracture surface of the welded joint,the delamination splitting with some cracks in the sharp corner of the welded joint and asymmetric dimples,LSP can cause brighter fracture surface,and finer and more uniform dimples.Finally,the schematic illustration of dimple formation with LSP is clearly described.The proposed research ensures that the LSP technology can clearly improve the yield strength,tensile strength,yield-to-tensile strength ratio,elongation,area reduction and elastic modulus of the welded joint.The enhancement mechanism of LSP on laser welded ANSI 304 stainless steel joint is mainly due to the fact that the refined and uniform dimples effectively delay the fracture of laser welded joints.     

Influence of flow conditions on the corrosion of AISI 304L stainless steel

Hydrodynamic and electrochemical noise measurements (ENMs), of AISI 304L stainless steel, were made in a pipe test section of 28 mm inside diameter for a range of flow regimes from laminar to turbulent. Mean flow velocities through the test section were controlled at 0.04, 0.07, 0.11, 0.36, 1.8 and 2.7 m s⁻¹, equivalent to Reynolds numbers of 1000, 2000, 3000, 10 000, 50 000 and 75 000, respectively. Standard hydrodynamic parameters were employed to characterise and evaluate the complex interrelationship between the mass transfer rate of oxygen and momentum transfer through turbulence to the metal/solution interface. For AISI 304L stainless steel, pitting typically occurs in the form of metastable pits which either repassivated before achieving stability or grow to become stable pits. Metastable pitting was evident under all flow regimes. The fluid flow, whether laminar or turbulent, had little overall effect on the nucleation rates of metastable pitting events. Conversely, stable pit growth was most evident during laminar flow immediately before the transition to turbulent flow and close to the critical velocity (∼1.5 m s⁻¹).     

AISI 304不锈钢铣削加工刀具磨损实验研究

AISI 304不锈钢具有低导热性和高韧性等特性,切削加工性较差。研究采用复合涂层硬质合金铣刀,对AISI 304不锈钢进行了端铣实验研究,考察后刀面磨损情况。实验表明,进给率对磨损的影响大于切削速度。针对刀具后刀面磨损,给出了相对较好的切削条件组合。     

304奥氏体不锈钢膨胀节应力腐蚀失效的几种形式及机理

本文分析了304奥氏体不锈钢波形膨胀节应力腐蚀失效案例,包括氯离子/湿硫化氢、湿硫化氢和连多硫酸三种情况的应力腐蚀.对这几种应力腐蚀的形式、产生的条件、形成的机理进行了分析.     

EBSD characterization of a hot worked 304 austenitic stainless steel under strain reversal

Monotonic and strain reversal hot torsion tests were performed on a 304 austenitic stainless steel, this led to changes in microstructures depending on the strain path. electron backscatter diffraction was used as the tool for characterizing the microstructures. It was possible to find some intragranular microstructural changes due to the reversal of the strain by means of several local and global misorientation-related parameters. Σ3 boundaries also showed sensitivity to strain reversal.     

水蒸气冷却润滑切削304不锈钢的试验研究

为实现304不锈钢的绿色切削,以过热水蒸气作冷却润滑介质,用Al2O3-TiC复相陶瓷刀具对304不锈钢进行单因素切削试验.试验结果表明:与干切削相比,用过热水蒸气冷却润滑切削时主切削力减小了6％ ～17％,加工表面硬化程度降低了3％～6％,并具有较高的加工表面质量.根据试验结果和冷却润滑作用机理分析可知,过热水蒸气具有较好的冷却润滑作用,且廉价无污染,有望实现304不锈钢的绿色切削.     

The microstructure and wear behaviour of friction stir processed AISI 430 ferritic stainless steel

ABSTRACT

The microstructure and wear behavior of Friction Stir Processed (FSPed) AISI 430 ferritic stainless steel were analyzed in the present study. FSP was performed with a tool rotation and advancing speeds of 1400?rpm 16?mm/min respectively by employing a tungsten carbide tool. The FSPed microstructure consisted of a mixture of ferrite and martensite. After FSP, microhardness increased with respect to that of the as-received material. The wear resistance of the FS processed material was significantly enhanced if compared to that of the as-received substrate. According to the SEM analyses of the worn surfaces and wear debris, a combination of adhesive wear and delamination was observed in the case of the base metal. The wear mechanism shifted to mild adhesive wear after FSP. The superior wear resistance of the FS processed AISI 430 steel was attributed to the pronounced grain refinement and to martensite formation in the stir zone.