scholarly journals Mechanical Properties Study of Fe-Mn-Si Shape Memory Alloys Welding Seam Formed by Laser Welding with Filler Powder

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1454 ◽  
Author(s):  
Heng Ju ◽  
Chengxin Lin ◽  
Yun Tian ◽  
Zhijie Liu ◽  
Huiling Jiang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Strength ◽  
Laser Welding ◽  
Strengthening Mechanism ◽  
304 Stainless Steel ◽  
Distribution Law ◽  
Welding Seam ◽  
Filler Powder

To reduce the residual stress and improve the fatigue property of the laser weldment by using the stress self-accommodation characteristic of Fe-Mn-Si shape memory alloys (SMAs), a Fe15Mn5Si12Cr6Ni memory alloy welding seam was formed inside 304 stainless steel by laser welding with filler powder. The combination of the hole-drilling method and the ANSYS software was used to research the distribution law of residual stress inside the laser welding specimen. The fatigue strength of the laser welded specimens with the Fe-Mn-Si SMAs welding seam (experimental materials) and 304 stainless steel welding seam (comparative materials) was measured by cycle bending fatigue test. The microhardness of the welding specimens was measured by the microhardness tester. The thermodynamic model of the laser welding process and the phase transition crystallography of Fe-Mn-Si SMAs were evaluated to analyze the strengthening mechanism of the mechanical properties in the experimental materials. The results show that the distribution law for residual stress in the experiment and simulation are consistent. The experimental materials possess low residual stress, high fatigue strength and high microhardness. The strengthening mechanism for mechanical properties is the welding residual stress-induced γ→ε martensitic transformation inside the experimental materials, which causes the tensile plastic strain of the welding seam to resist residual compression strain, and the residual stress, as the transition driving force, is released in shear processing.

scholarly journals Residual Stresses Induced by Surface Working and Their Improvement by Emery Paper Polishing

2020 ◽  
Vol 4 (2) ◽  
pp. 21
Author(s):  
Makoto Hayashi
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Diffraction Method ◽  
304 Stainless Steel ◽  
Heat Treated ◽  
Emery Paper ◽  
Type 304 ◽  
Type 304 Stainless Steel

In many of machine parts and structural components, materials surface would be worked. In this study, residual stresses on the surfaces were measured by X-ray diffraction method, and effects of surface working on the residual stresses were examined. In case of lathe machining of type 304 stainless steel bar, the residual stresses in circumferential directions are tensile, and those in axial directions are almost compressive. Highly tensile residual stresses in the circumferential directions were improved by emery paper polishing. 10 to 20 times of polishing changes high tensile residual stresses to compressive residual stresses. In the case of shot peening on a type 304 stainless steel plate, the compressive residual stress inside is several hundred MPa lower than that on the surface. By applying the emery paper polishing to the shot peened surface 10 or 20 times, the residual stress on the surface is improved to −700 MPa. While fatigue strength at 288 °C in the air of the shot peened material is 30 MPa higher than solution heat treated and electro-polished material, the fatigue strength of the shot peened and followed by emery paper polished material is 60 MPa higher. Thus, the emery paper polishing is simple and a very effective process for improvement of the residual stresses.

Investigation on Mechanical Properties of Pulsed Nd:YAG Laser Welding on AISI 304 Stainless Steel to AISI 1008 Steel

2011 ◽  
Vol 117-119 ◽  
pp. 402-408
Author(s):  
Shazarel Shamsudin ◽  
Phoon Chee Yoon
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Stainless Steel ◽  
Laser Welding ◽  
High Energy ◽  
High Energy Density ◽  
304 Stainless Steel ◽  
Aisi 304 Stainless Steel ◽  
Aisi 304 ◽  
Pulsed Nd:Yag Laser Welding

Product with low cost, lightweight and enhanced mechanical properties were the main reasons welding dissimilar materials thrived by most of the industries. The laser welding technique which has high-energy density beam was found suitable of carrying this task. This paper attempts to investigate welding of AISI 304 stainless steel to AISI 1008 steel through Nd:YAG pulse laser method. The main objective of this study was to find out the weldability of these materials and investigate the mechanical properties of the welded butt joints. Peak power, pulse duration and weld speed combinations were carefully selected with the aims of producing weld with a good tensile strength, minimum heat affected zone (HAZ) and acceptable welding profile. Response surface methodology (RSM) approach was adopted as statistical design technique for tensile strength optimization. Statistical based mathematical model was developed to describe effects of each process parameters on the weld tensile strength and for response prediction within the parameter ranges. The microstructure of the weld and heat affected zones were observed via optical microscope. The results indicate the developed model can predict the response within ±9% of error from the actual values.

scholarly journals Effect of Micro-Shot Peening on the Fatigue Performance of AISI 304 Stainless Steel

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1408
Author(s):  
Yu-Hsuan Chung ◽  
Tai-Cheng Chen ◽  
Hung-Bin Lee ◽  
Leu-Wen Tsay
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Stainless Steel ◽  
Fatigue Strength ◽  
Strain Hardening ◽  
Fatigue Resistance ◽  
Shot Peening ◽  
304 Stainless Steel ◽  
Aisi 304 Stainless Steel ◽  
Aisi 304

The effects of micro-shot peening on the rotating bending fatigue resistance of AISI 304 stainless steel (SS) were investigated in this study. The strain-hardening, surface roughness and induced residual stress were inspected and correlated with fatigue strength. Micro-shot peening caused intense strain-hardening, phase transformation and residual stress but was also accompanied by a minor increase in surface roughness. A nanograined structure, which was advantageous to fatigue resistance, was observed in the severe shot-peened layer. The absence of microcracks, minor increase in surface roughness, nanograined structure and induced high compressive residual stress in the shot-peened layer were responsible for the improved fatigue strength of AISI 304 SS.

scholarly journals Influence of Residual Stress on Fatigue Design of AISI 304 Stainless Steel

2011 ◽  
Vol 7 (2) ◽  
pp. 44 ◽  
Author(s):  
L. Singh ◽  
R.A. Khan ◽  
M.L. Aggarwal
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Strength ◽  
Stress Field ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Residual Stress Field ◽  
Aisi 304 ◽  
Fatigue Design

 Austenitic stainless steel cannot be hardened by any form of heat treatment, in fact, quenching from 10000C merely softens them. They are usually cold worked to increase the hardness. Shot peening is a cold working process that changes micro-structure as well as residual stress in the surface layer. In the present work, the compressive residual stress and fatigue strength of AISI 304 austenitic stainless steel have been evaluated at various shot peening conditions. The improvement in various mechanical properties such as hardness, damping factors and fatigue strength was noticed. Compressive residual stress induced by shot peening varies with cyclic loading due to relaxation of compressive residual stress field. The consideration of relaxed compressive residual stress field instead of original compressive residual stress field provides reliable fatigue design of components. In this paper, the exact reductions in weight and control of mechanical properties due to shot peening process are discussed. 

Study on Defect of 304 Stainless Steel Industrial Condensation Board in CO2 Laser Welding

2011 ◽  
Vol 189-193 ◽  
pp. 3437-3440
Author(s):  
Jian Luo ◽  
Ke Liang Xue ◽  
Fei Li ◽  
J.F. Xiang ◽  
D.K. Yin
Keyword(s):  
Stainless Steel ◽  
Laser Welding ◽  
Tensile Tests ◽  
Optical Microscope ◽  
304 Stainless Steel ◽  
Stainless Steel Sheet ◽  
Micro Hardness ◽  
Welding Seam ◽  
Cooling Velocity ◽  
Flowing Channel

Based on the welding problems of 304 stainless steel serpentine flow industrial condensation plate, the three kinds of CO2 laser welding procedures are adopted to manufacture the condensation plate. The optical microscope, SEM, EDS, micro-hardness and tensile tests are used to analyze the microstructure and micro-hardness of 304 stainless steel sheet joint. The relationships between the generated defects and carbide separation in the welding joint are discussed. Due to the grain refinement, the micro-hardness of welding seam is increased. Therefore, it is reasonable factors that the heat input, cooling velocity and temperature gradient to improve the defects of 304 stainless steel serpentine flowing channel industrial condensation board in CO2 laser welding.

Microstructures and Mechanical Properties of Hundred-Millimeter-Grade 304 Stainless Steel Joints by Ultra-Narrow Gap Laser Welding

2018 ◽  
Vol 45 (7) ◽  
pp. 0702005
Author(s):  
杨武雄 Yang Wuxiong ◽  
信纪军 Xin Jijun ◽  
方超 Fang Chao ◽  
戴文华 Dai Wenhua ◽  
卫靖 Wei Jing ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Laser Welding ◽  
304 Stainless Steel ◽  
Narrow Gap ◽  
Microstructures And Mechanical Properties ◽  
Steel Joints

scholarly journals Investigations into the Improvement of the Mechanical Properties of Ti-5Al-4Mo-4Cr-2Sn-2Zr Titanium Alloy by Using Low Energy Laser Peening without Coating

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1398
Author(s):  
Dingyuan Xue ◽  
Yang Jiao ◽  
Weifeng He ◽  
Xiaojun Shen ◽  
Yangjun Gao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Titanium Alloy ◽  
Fatigue Strength ◽  
Dynamic Equilibrium ◽  
Laser Energy ◽  
Strengthening Mechanism ◽  
Laser Peening ◽  
Micro Hardness ◽  
Laser Peening Without Coating

Mechanical properties, such as residual stress, micro-hardness and fatigue performance, of the Ti-5Al-4Mo-4Cr-2Sn-2Zr titanium alloy were improved via the laser peening without coating (LPwC) with a water-penetrable wavelength of 532 nm and pulse duration of 10 ns. In this paper, three kinds of laser energy, namely 85, 110 and 160 mJ were used to process the samples. The titanium alloy samples were also peened with different impact times (1, 3 or 5 impacts) at the energy of 85 mJ. The micro-hardness and residual stress distribution results provided that LPwC can introduce compressive residual stress (CRS) and also induce hardening of the target materials. Further, micro-hardness and CRS showed the increasing trends when the laser impact times increased. However, the CRS and micro-hardness decreased while the laser energy increased from 110 to 160 mJ, which was attributed to the dynamic equilibrium between the thermal and mechanical effects of LPwC. High cycle fatigue strength of the titanium alloy was significantly improved from 360 to 490.3 MPa after three impacts LPwC. The strengthening mechanism of fatigue strength subjected to LPwC was a combined effect between the laser-induced CRS and the high-density dislocations.

scholarly journals Effects of Surface Severe Plastic Deformation on the Mechanical Behavior of 304 Stainless Steel

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 831
Author(s):  
Yang Li ◽  
Zhengtong Lu ◽  
Tingchao Li ◽  
Dalei Li ◽  
Jinsheng Lu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Plastic Deformation ◽  
Stainless Steel ◽  
Severe Plastic Deformation ◽  
Mechanical Behavior ◽  
High Strength ◽  
304 Stainless Steel ◽  
Abrasive Waterjet ◽  
Positive Effects

In this study, two innovative surface severe plastic deformation (SSPD) methods, namely abrasive waterjet peening (AWJP) and ultrasonic nanocrystal surface modification (UNSM), were applied to a 304 stainless steel to improve the mechanical behavior. The surface roughness, microstructure, residual stress, hardness, and tensile mechanical properties of the alloy after the two SSPD treatments were studied systematically. The results show that both the AWJP and UNSM treatments have greatly positive effects on the mechanical-properties improvements by successfully introducing a hardening layer. Especially the UNSM-processed specimen possesses the most outstanding comprehensive mechanical properties (high strength with the comparable ductility). The yield strength with the UNSM treatment is 443 MPa, corresponding to the 109% and 19% improvements, as compared to that of the base (212 MPa) and AWJP-treated specimens (372 MPa). The results can be attributed to a much thicker hardening layer (about 500 μm) and a better surface integrity with lower roughness (Ra: 0.10 μm) formed by the UNSM technique.

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