scholarly journals Effects of High Toughness and Welding Residual Stress for Unstable Fracture Prevention

2020 ◽  
Vol 10 (23) ◽  
pp. 8613
Author(s):  
Gyubaek An ◽  
Jeongung Park ◽  
Ilwook Han
Keyword(s):  
Residual Stress ◽  
Brittle Fracture ◽  
Compressive Stress ◽  
Fracture Prevention ◽  
Residual Compressive Stress ◽  
Welding Residual Stress ◽  
Propagation Path ◽  
Unstable Fracture ◽  
Welding Consumable ◽  
Unstable Fractures

Unstable fractures generally occur in brittle materials under low-temperature service conditions. Toughness and welding residual stress are the main factors that should be evaluated when defining a brittle crack propagation path. In this study, a rainbow welding technique was proposed and confirmed as being significantly useful in preventing unstable fractures in weld joints. The residual compressive stress in the crack front was particularly useful for decreasing the possibility of brittle fracture. The objective was to examine the effect of high welding consumable toughness welding residual stress, especially for avoiding brittle fracture through welding residual compressive stress.

Numerical simulation of the effect of ultrasonic impact treatment on welding residual stress

2021 ◽  
pp. 2150175
Author(s):  
Tao Mo ◽  
Jingqing Chen ◽  
Pengju Zhang ◽  
Wenqian Bai ◽  
Xiao Mu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Compressive Stress ◽  
Welded Joints ◽  
Welding Process ◽  
Residual Compressive Stress ◽  
Welding Residual Stress ◽  
304 Stainless Steel ◽  
Residual Tensile Stress ◽  
Ultrasonic Impact Treatment

Ultrasonic impact treatment (UIT) is an effective method that has been widely applied in welding structure to improve the fatigue properties of materials. It combines mechanical impact and ultrasonic vibration to produce plastic deformation on the weld joints surface, which introduces beneficial compressive residual stress distribution. To evaluate the effect of UIT technology on alleviating the residual stress of welded joints, a novel numerical analysis method based on the inherent strain theory is proposed to simulate the stress superposition of welding and subsequent UIT process of 304 stainless steel. Meanwhile, the experiment according to the process was carried out to verify the simulation of residual stress values before and after UIT. By the results, optimization of UIT application could effectively reduce the residual stress concentration after welding process. Residual tensile stress of welded joints after UIT is transformed into residual compressive stress. UIT formed a residual compressive stress layer with a thickness of about 0.13 mm on the plate. The numerical simulation results are consistent with the experimental results. The work in this paper could provide theoretical basis and technical support for the reasonable evaluation of the ultrasonic impact on residual stress elimination and mechanical properties improvement of welded joints.

Effect of 7050 Aluminium Alloy Microstructure on Residual Stress by Laser Shock Processing

2012 ◽  
Vol 463-464 ◽  
pp. 1363-1367
Author(s):  
M.L. Zhang ◽  
J.M. Wang ◽  
Y.F. Jiang ◽  
Q.L. Zhang ◽  
Q.L. Zhou
Keyword(s):  
Residual Stress ◽  
Aluminium Alloy ◽  
Compressive Stress ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Residual Compressive Stress ◽  
Original Structure ◽  
Laser Shock ◽  
Laser Shock Processing ◽  
Shock Processing

The solution treatment and solution and aging treatment (T6) were disposed on 7050 aluminium alloy, then local processed by laser shock processing (LSP) with high-rate neodymium glass laser. The microhardness and residual stress on the surface of 7050 aluminium alloy were tested, then how the microstructure influences the residual stress on the surface of 7050 aluminium alloy by laser shock processing was analysed. The results show that the microhardness and residual compressive stress on the surface of 7050 aluminium alloy treated by solution and aging treatment was higher, and decreased obviously treated by solution treatment; the microhardness and residual compressive stress on the surface of 7050 aluminium alloy increased obviously by solution treatment and solution and aging treatment after laser shock processing; treated by solution treatment and solution and aging treatment, the microhardness and residual compressive stress of the material with uniform original structure was higher than the material with nonuniform original structure.

scholarly journals Investigation on Residual Stress Loss during Laser Peen Texturing of 316L Stainless Steel

2019 ◽  
Vol 9 (17) ◽  
pp. 3511 ◽  
Author(s):  
Kangmei Li ◽  
Yifei Wang ◽  
Yu Cai ◽  
Jun Hu
Keyword(s):  
Residual Stress ◽  
Compressive Stress ◽  
Power Density ◽  
Laser Power ◽  
Surface Deformation ◽  
Laser Power Density ◽  
Residual Compressive Stress ◽  
Laser Spot ◽  
Residual Tensile Stress ◽  
Spot Radius

Laser peen texturing (LPT) is a novelty way of surface texturing based on laser shock processing. One of the most important benefits of LPT is that it can not only fabricate surface textures but also induce residual compressive stress for the target material. However, the residual stress loss leads to partial loss of residual compressive stress and even causes residual tensile stress at the laser spot center. This phenomenon is not conducive to improving the mechanical properties of materials. In this study, a numerical simulation model of LPT was developed and validated by comparison of surface deformation with experiments. In order to investigate the phenomenon of residual stress loss quantitatively, an evaluation method of residual stress field was proposed. The effects of laser power density and laser spot radius on the residual stress, especially the residual stress loss, were systematically investigated. It is found that with the increase of laser power density or laser spot radius, the thickness of residual compressive layer in depth direction becomes larger. However, both the magnitude and the affecting zone size of residual stress loss will be increased, which implies a more severe residual stress loss phenomenon.

Study on Pre-Stress Cutting of Bearing Race and Its Machined Surface State

2006 ◽  
Vol 532-533 ◽  
pp. 528-531 ◽  
Author(s):  
Bang Yan Ye ◽  
Bo Wu ◽  
Jian Ping Liu ◽  
Xiao Chu Liu ◽  
Xue Zhi Zhao
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Compressive Stress ◽  
Contact Fatigue ◽  
Residual Compressive Stress ◽  
Residual Tensile Stress ◽  
Machined Surface ◽  
Residual Stress State ◽  
Bearing Race ◽  
Hard Cutting

Theoretical analysis and experiments on bearing race show that a suitable residual compressive stress on roll path of bearing race can prolong its contact fatigue life. However, residual tensile stress is often found on workpiece surface of bearing race. To actively control the residual stress state and improve fatigue life of bearing part, a new method of pre-stress hard cutting is applied. In this paper, the principle of pre-stress hard cutting for bearing race is introduced as well as the experiments on it. In the experiments, residual stress, hardness and roughness of machined surface are measured and analyzed. Moreover, micro-topography and texture characteristics of machined surface are investigated and experimental results are compared with that by grinding. It is found that we can get residual compressive stress and fine quality on machined surface of bearing race by pre-stress hard cutting and increase its productivity as well.

Effect of Welding Residual Stress and Plastic Constraint on Brittle Fracture of a High Strength Steel

2009 ◽  
Author(s):  
Masaki Torigoe ◽  
Yoichi Yamashita ◽  
Takehisa Yamada
Keyword(s):  
Residual Stress ◽  
Brittle Fracture ◽  
High Strength Steel ◽  
Crack Tip ◽  
High Strength ◽  
Fracture Initiation ◽  
Parent Material ◽  
Welding Residual Stress ◽  
Cross Sectional ◽  
Plastic Constraint

This paper investigates the effect of welding residual stress and plastic constraint on brittle fracture of a 780 MPa class high-strength steel (HT780). In order to investigate the effect of welding residual stress, three point bend (3PB) fracture toughness tests were conducted using the parent-material specimens and groove-welded specimens which were prepared to have the same cross-sectional proportion; i.e., a ratio of thickness to width of 0.5. Crack length was determined so that the crack tip was located in the base-metal zone far from the heat-affected zone of the welded specimen to eliminate the effect of any degradation of the parent-material property on fracture resistance. Also, in order to investigate the effect of constraint, tensile loading tests in which the plastic constraint was expected to be less than 3PB were conducted using welded specimens as the same as employed in the 3PB test. Three dimensional finite element (FE) analyses were performed to evaluate the stress state near the crack tip at the point of brittle fracture initiation for each test condition. From the results of experiments and FE analyses, it is confirmed that the fracture test results can be evaluated using J or KJ – Q theory, by considering enhancement or reduction due to residual stress.

The Mitigation of Weld Residual Stress on 304L Stainless Steel by Post Weld Cool Treatment Process

2016 ◽  
Vol 853 ◽  
pp. 209-215 ◽  
Author(s):  
Wen Ting Jia ◽  
Jian Ping Zhao ◽  
Jun Cao
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Compressive Stress ◽  
Cooling Time ◽  
Welding Residual Stress ◽  
304L Stainless Steel ◽  
Factors Affecting ◽  
Preheating Temperature ◽  
Cool Treatment ◽  
Weld Cool

The High Welding Residual Stress is the Main Factors Affecting the Service Life of Welded Structures. Post Weld Cool Treatment (PWCT) is a Novel Method by Introducing Reverse Process Welding Temperature Field to Eliminate the Residual Stress and to Obtain Compressive Stress Layer. the Major Factors Affecting the Effects of Post Weld Cool Treatment (PWCT) is Preheating Temperature, Cooling Time and Cooling Range. in this Paper, a Model to Calculate the Residual Stress was Built Using Finite Element Code ABAQUS, and Different PWCT Processes were Applied on 304L Stainless Steel Specimens. at the same Time, Impact Indentation Method (IIM) was Used to Measure the Residual Stress on the Specimens. the Results Show that the Longitudinal Stress and the Transverse Stress were Reduced Obviously and Compressive Stress was Generated after PWCT in both of the Simulation and the Experiment. the Proposal Preheating Temperature was 400°C and the Cooling Range was 2 Times of Weld Width. Besides, the Cooling Time had Little Effect on the Residual Stress.

Effect of residual stress and microstructure on corrosion resistance of carburised 18CrNiMo7-6 steel

2020 ◽  
Vol 67 (4) ◽  
pp. 357-366
Author(s):  
Gang Wang ◽  
Yue Zhang ◽  
Chen Gao ◽  
GuangTao Xu ◽  
MingHao Zhao
Keyword(s):  
Aqueous Solution ◽  
Residual Stress ◽  
Compressive Stress ◽  
High Speed ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Electrochemical Potential ◽  
Residual Compressive Stress ◽  
Content Type ◽  
Electrochemical Tests

Purpose The purpose of this paper is to investigate, the effects of residual stress and microstructure on the corrosion behaviour of carburised 18CrNiMo7-6 steel in a 3.5% NaCl aqueous solution. Design/methodology/approach The electrochemical tests were conducted using an electrochemical workstation with a three-electrode system in a 3.5% NaCl aqueous solution, the residual stress of each working face was measured by a high-speed residual stress analyser, and microstructure of different carburised layers were observed scanning electron microscopy. Finally, the effect of carbon content, microstructure and residual stress on the corrosion behaviour of the steel was discussed. Findings The results showed that the residual compressive stress in the carburised layer initially increased and subsequently decreased with increasing depth of the carburised layer, reaching stability in the matrix layer. The electrochemical tests before and after stress reduction showed that the electrochemical impedance and the electrochemical potential increased with the reduction of residual compressive stress. Originality/value The residual compressive stress in the carburised layer initially increases and subsequently decreases with increasing carburised layer depth. The electrochemical impedance and the electrochemical potential increased with the reduction of residual compressive stress. The general relationship between electrochemical potential and residual stress was established.

The Effect of Welding Residual Stress Distribution in Thickness Direction With Thick Steel Plate to Identification of Fracture Toughness

2016 ◽  
Author(s):  
Gyubaek An ◽  
Wanchuck Woo ◽  
Jeongung Park
Keyword(s):  
Residual Stress ◽  
Crack Propagation ◽  
Steel Plate ◽  
Welding Process ◽  
Welding Residual Stress ◽  
Steel Plates ◽  
Propagation Path ◽  
Crack Propagation Path ◽  
Flux Cored Arc Welding ◽  
Thick Steel

Along with the rapid increase in the size of welding structures, the steel plate used for structure has been increased in thickness. Especially, the growing capacity of large scale ships such as container ships has led to an increase in the thickness and the strength of steel plates for shipbuilding. The toughness and the resistance to brittle fractures of the steel plate tend to decrease for thick plates, which is a result of the so-called thickness effect. Steel plates with 80mm thickness were used and two welding processes, which are flux cored arc welding (FCAW) process and electron gas welding process (EGW), were used to produce full thickness weld joints. To evaluate of brittle crack propagation path, measurement of welding residual stress in both welded joint. In this study, it was aimed to investigate the effect of welding variables on the crack arrest toughness and crack propagation path of thick steel plate welds. Quantitative analysis by temperature gradient ESSO test was conducted to clarify the effect of welding variables for flux cored arc welding (FCAW) and electro gas welding (EGW) joint of thick steel plates with the thickness of 50 and 80mm. Also, welding residual stress was measured for evaluate of welding residual stress effect in both welding process in brittle crack propagation path using neutron science analysis.

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