Pub Date : 2024-05-15DOI: 10.21741/9781644903131-35
A. Perna
Abstract. The quality of the surface is one of the most important factors in the fabrication of a component via additive manufacturing (AM). In particular, when considering the manufacture of workpieces in titanium and its alloys the successful use of surface treatments is essential. In fact, many fracture-related events, in particular fatigue cracks, start near the surface of the component. Numerous techniques based on machining, shot peening, or laser polishing have been proposed to enhance the surface quality. The limitations of these treatments stem from the challenges posed by focusing on complex form components. One of the most promising approaches for achieving homogenous smoothing of intricate objects with internal channels and lattice structure continues to be chemical-based surface treatments. It is a pivotal method to remove material that has been polluted by oxygen during processing. In this instance, the resistance to crack initiation and fracture is fundamentally improved by the removal of a hard, brittle top layer. In this work, HF/HNO3-based treatment tailored for 3D printed design products is presented.
摘要表面质量是通过增材制造（AM）制造部件的最重要因素之一。特别是在考虑用钛及其合金制造工件时，成功使用表面处理技术至关重要。事实上，许多与断裂相关的事件，尤其是疲劳裂纹，都是从部件表面开始的。为了提高表面质量，人们提出了许多基于机械加工、喷丸强化或激光抛光的技术。这些处理方法的局限性来自于复杂形状部件所带来的挑战。对于具有内部通道和晶格结构的复杂物体，实现均匀平滑的最有前途的方法之一仍然是基于化学的表面处理。这是去除加工过程中被氧气污染的材料的关键方法。在这种情况下，通过去除坚硬、脆性表层，从根本上提高了抗裂纹产生和断裂的能力。在这项工作中，介绍了为 3D 打印设计产品量身定制的基于 HF/HNO3 的处理方法。
{"title":"Improvement of the surface quality of titanium-based design objects produced through WAAM technology using chemical machining: A preliminary study","authors":"A. Perna","doi":"10.21741/9781644903131-35","DOIUrl":"https://doi.org/10.21741/9781644903131-35","url":null,"abstract":"Abstract. The quality of the surface is one of the most important factors in the fabrication of a component via additive manufacturing (AM). In particular, when considering the manufacture of workpieces in titanium and its alloys the successful use of surface treatments is essential. In fact, many fracture-related events, in particular fatigue cracks, start near the surface of the component. Numerous techniques based on machining, shot peening, or laser polishing have been proposed to enhance the surface quality. The limitations of these treatments stem from the challenges posed by focusing on complex form components. One of the most promising approaches for achieving homogenous smoothing of intricate objects with internal channels and lattice structure continues to be chemical-based surface treatments. It is a pivotal method to remove material that has been polluted by oxygen during processing. In this instance, the resistance to crack initiation and fracture is fundamentally improved by the removal of a hard, brittle top layer. In this work, HF/HNO3-based treatment tailored for 3D printed design products is presented.","PeriodicalId":515987,"journal":{"name":"Materials Research Proceedings","volume":"7 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140974431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-15DOI: 10.21741/9781644903131-282
Sanaz Afshariantorghabeh
Abstract. This study addressed the limitations of traditional post-production analyses in refining thermoforming operation by employing non-destructive, real-time thermal analysis, specifically employing thermal imaging. The focus was on assessing the thermoformability of plastic-coated paperboards, a recent area of interest in manufacturing. Three paperboards underwent vacuum and air pressure thermoforming, with continuous temperature monitoring. Findings revealed correlations between the temperature distributions, the thermal profiles, and the material shape formability. Direct analysis of the thermal images enabled accurate measurement of contact areas between the mold and material. Furthermore, temperature profiles were closely related to shape profiles, particularly concerning the depth, which might be due to exothermic response of the studied materials during the induced stretching process.
{"title":"Utilizing thermal imaging for non-destructive thermoformability assessment in vacuum-air pressure thermoforming of plastic-coated paperboards","authors":"Sanaz Afshariantorghabeh","doi":"10.21741/9781644903131-282","DOIUrl":"https://doi.org/10.21741/9781644903131-282","url":null,"abstract":"Abstract. This study addressed the limitations of traditional post-production analyses in refining thermoforming operation by employing non-destructive, real-time thermal analysis, specifically employing thermal imaging. The focus was on assessing the thermoformability of plastic-coated paperboards, a recent area of interest in manufacturing. Three paperboards underwent vacuum and air pressure thermoforming, with continuous temperature monitoring. Findings revealed correlations between the temperature distributions, the thermal profiles, and the material shape formability. Direct analysis of the thermal images enabled accurate measurement of contact areas between the mold and material. Furthermore, temperature profiles were closely related to shape profiles, particularly concerning the depth, which might be due to exothermic response of the studied materials during the induced stretching process.","PeriodicalId":515987,"journal":{"name":"Materials Research Proceedings","volume":"58 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140975060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-15DOI: 10.21741/9781644903131-243
Xavier Lemoine
Abstract. ArcelorMittal is constantly developing new steel grades to enable the automotive industry to offer safer, lighter, and more environmentally friendly vehicles. These new grades include advanced high-strength steels (AHSS) and Ultra High Strength steels (UHSS) having for some of them lower uniform elongation (UE) than conventional drawing steels. This particularity needs to be considered for an accurate formability prediction in sheet forming numerical simulations. One of these difficulties is the effect of the relatively low uniform elongation on the identification of the parameters of the isotropic hardening model. Various experimental tests can be used to reach the large plastic deformation (hydraulic bulge test, stack compression test, shear test, torsion test or plane strain compression test). The identification protocol of ArcelorMittal for hardening models is based solely on stress-strain curves determined in uniaxial tension. The Exp_S hardening law (TU experimental values before UE%, Swift extension above) was validated by comparison with the stress-strain curves obtained from measurements of experimental tests reaching large strains.
摘要安赛乐米塔尔正在不断开发新的钢种，以使汽车行业能够提供更安全、更轻便、更环保的汽车。这些新钢种包括高级高强度钢（AHSS）和超高强度钢（UHSS），其中一些钢种的均匀伸长率（UE）低于传统的拉拔钢。要在板材成型数值模拟中准确预测可成形性，就必须考虑这种特殊性。其中一个困难是相对较低的均匀伸长率对确定各向同性硬化模型参数的影响。为达到大塑性变形，可采用各种实验测试（液压鼓包测试、堆叠压缩测试、剪切测试、扭转测试或平面应变压缩测试）。安赛乐米塔尔公司对硬化模型的识别规程完全基于单轴拉伸中测定的应力-应变曲线。Exp_S 硬化定律（UE% 前的 TU 实验值，上述 Swift 扩展）通过与达到大应变的实验测试测量所获得的应力-应变曲线进行比较而得到验证。
{"title":"A robust identification protocol of flow curve adjusting parameters using uniaxial tensile curve","authors":"Xavier Lemoine","doi":"10.21741/9781644903131-243","DOIUrl":"https://doi.org/10.21741/9781644903131-243","url":null,"abstract":"Abstract. ArcelorMittal is constantly developing new steel grades to enable the automotive industry to offer safer, lighter, and more environmentally friendly vehicles. These new grades include advanced high-strength steels (AHSS) and Ultra High Strength steels (UHSS) having for some of them lower uniform elongation (UE) than conventional drawing steels. This particularity needs to be considered for an accurate formability prediction in sheet forming numerical simulations. One of these difficulties is the effect of the relatively low uniform elongation on the identification of the parameters of the isotropic hardening model. Various experimental tests can be used to reach the large plastic deformation (hydraulic bulge test, stack compression test, shear test, torsion test or plane strain compression test). The identification protocol of ArcelorMittal for hardening models is based solely on stress-strain curves determined in uniaxial tension. The Exp_S hardening law (TU experimental values before UE%, Swift extension above) was validated by comparison with the stress-strain curves obtained from measurements of experimental tests reaching large strains.","PeriodicalId":515987,"journal":{"name":"Materials Research Proceedings","volume":"19 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140971668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-15DOI: 10.21741/9781644903131-136
Jinjin Ha
Abstract. In response to stringent environmental regulations, the automotive industry is increasingly prioritizing lightweighting, prompting a shift towards high-strength aluminum alloys while the low formability of these alloys remain a limiting factor. This study explores a solution through a two-step forming process applied to AA7075 sheets utilizing -T6 and -W tempers. Firstly, two-step uniaxial tension experiments are performed at two prestraining levels in the -T6 temper followed by subsequent tensions in the -W. Both cases exhibit significant plastic deformation before fracture, overcoming the thinning accumulated in the first step. Additionally, a two-step hole expansion experiment is conducted under the same tempering conditions. Results are compared with single operations in each temper, evaluating force-displacement curves and thickness strain distribution around the hole. The study highlights the substantial contribution to formability enhancement, demonstrating 80% higher cup height and twice greater thinning to fracture compared to conventional single-step operations.
{"title":"Enhanced formability in two-step forming for AA7075 sheet in -T6 and -W tempers","authors":"Jinjin Ha","doi":"10.21741/9781644903131-136","DOIUrl":"https://doi.org/10.21741/9781644903131-136","url":null,"abstract":"Abstract. In response to stringent environmental regulations, the automotive industry is increasingly prioritizing lightweighting, prompting a shift towards high-strength aluminum alloys while the low formability of these alloys remain a limiting factor. This study explores a solution through a two-step forming process applied to AA7075 sheets utilizing -T6 and -W tempers. Firstly, two-step uniaxial tension experiments are performed at two prestraining levels in the -T6 temper followed by subsequent tensions in the -W. Both cases exhibit significant plastic deformation before fracture, overcoming the thinning accumulated in the first step. Additionally, a two-step hole expansion experiment is conducted under the same tempering conditions. Results are compared with single operations in each temper, evaluating force-displacement curves and thickness strain distribution around the hole. The study highlights the substantial contribution to formability enhancement, demonstrating 80% higher cup height and twice greater thinning to fracture compared to conventional single-step operations.","PeriodicalId":515987,"journal":{"name":"Materials Research Proceedings","volume":"63 42","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140972299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-15DOI: 10.21741/9781644903131-82
S. Di Donato
Abstract. In the cold wire drawing process, the stress acting on the wire depends on process parameters, as well as on the material flow stress, including the strain-hardening that occurs step by step. It is essential to ensure that the stress applied to the wire at the exit of the die remains below the material's yield stress, to prevent wire necking and fracture. Industrially, the process is carried out continuously using multi-step-multi-wires machines that deform the material to high strain at elevated strain rate values. The application of analytical models for evaluating the stresses acting on the wire assumes simplified boundary conditions, such as an average distribution of strain and strain rate within the die. Further studies are necessary, considering the entire multi-pass industrial case and involving finite element simulation, which is today the main tool for optimizing industrial processes. In this work, the drawing process applied to ETP Pure Copper (99.9% in weight) is analyzed experimentally, analytically, and numerically. The material was characterized by torsion tests and experimental drawing tests were carried out on four steps of the process. Through the analysis of the different analytical methods, it was shown that a careful evaluation of the friction coefficient values is necessary to reduce errors in estimating the drawing forces. The aim is to provide a reliable numerical model for predicting the stress acting on the wire during the multi-pass drawing process, through an appropriate characterization of the material flow stress and an evaluation of the friction model.
{"title":"Experimental, analytical, and numerical analysis of the copper wire multi-pass drawing process","authors":"S. Di Donato","doi":"10.21741/9781644903131-82","DOIUrl":"https://doi.org/10.21741/9781644903131-82","url":null,"abstract":"Abstract. In the cold wire drawing process, the stress acting on the wire depends on process parameters, as well as on the material flow stress, including the strain-hardening that occurs step by step. It is essential to ensure that the stress applied to the wire at the exit of the die remains below the material's yield stress, to prevent wire necking and fracture. Industrially, the process is carried out continuously using multi-step-multi-wires machines that deform the material to high strain at elevated strain rate values. The application of analytical models for evaluating the stresses acting on the wire assumes simplified boundary conditions, such as an average distribution of strain and strain rate within the die. Further studies are necessary, considering the entire multi-pass industrial case and involving finite element simulation, which is today the main tool for optimizing industrial processes. In this work, the drawing process applied to ETP Pure Copper (99.9% in weight) is analyzed experimentally, analytically, and numerically. The material was characterized by torsion tests and experimental drawing tests were carried out on four steps of the process. Through the analysis of the different analytical methods, it was shown that a careful evaluation of the friction coefficient values is necessary to reduce errors in estimating the drawing forces. The aim is to provide a reliable numerical model for predicting the stress acting on the wire during the multi-pass drawing process, through an appropriate characterization of the material flow stress and an evaluation of the friction model.","PeriodicalId":515987,"journal":{"name":"Materials Research Proceedings","volume":"88 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140973190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-15DOI: 10.21741/9781644903131-219
Sílvia Daniela RIBEIRO CARVALHO
Abstract. The surface texture is normally observed after the machining process, but nowadays it is important to use on-site analysis to improve the process automatically via smart processing. This study introduces a contactless roughness inspection method employing digital image processing on Ti6Al4V samples in turning using three different feed. Texture analysis with grey-level co-occurrence matrix (GLCM) extracted features that were correlated with the arithmetic average roughness (Ra), leading to the establishment of predictive models. The study encompassed diverse image testing, incorporating variations in resolution and brightness distributions. It was found that the pixel pair spacing (PPS) in GLCM analysis was influenced by the image resolution and feed rate. The predictive models developed with high-quality images, i.e., higher resolution and better brightness distribution, yielded similar results to those created using lower-quality images.
{"title":"Digital image processing algorithm for industrial on-site roughness evaluation in Ti-alloy machining","authors":"Sílvia Daniela RIBEIRO CARVALHO","doi":"10.21741/9781644903131-219","DOIUrl":"https://doi.org/10.21741/9781644903131-219","url":null,"abstract":"Abstract. The surface texture is normally observed after the machining process, but nowadays it is important to use on-site analysis to improve the process automatically via smart processing. This study introduces a contactless roughness inspection method employing digital image processing on Ti6Al4V samples in turning using three different feed. Texture analysis with grey-level co-occurrence matrix (GLCM) extracted features that were correlated with the arithmetic average roughness (Ra), leading to the establishment of predictive models. The study encompassed diverse image testing, incorporating variations in resolution and brightness distributions. It was found that the pixel pair spacing (PPS) in GLCM analysis was influenced by the image resolution and feed rate. The predictive models developed with high-quality images, i.e., higher resolution and better brightness distribution, yielded similar results to those created using lower-quality images.","PeriodicalId":515987,"journal":{"name":"Materials Research Proceedings","volume":"64 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140973611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-15DOI: 10.21741/9781644903131-97
J. Peddinghaus
Abstract. Recent advances in the field of additive manufacturing (AM) have enabled the utilisation of Laser Powder Bed Fusion (L-PBF) for tool steels under high load conditions. Design elements, such as internal cooling channels, which are not achievable through subtractive manufacturing can therefore be used to functionalise and optimise hot forging tools. Thermal control is crucial for hot forging dies as the performance and endurance of the tools is highly dependent on the input and dissipation of heat in the surface zone during forging. A modified forging tool with conformal internal cooling channels generated through a hybrid L-PBF manufacturing process was developed in prior work [1]. The objective in the presented research is the experimental evaluation of the effect of conformal temperature control in the novel tool concept on the temperature dependent tool deterioration mechanisms in forging conditions. The actively controlled water temperature was varied between room temperature for maximum cooling and 180 °C, representing an exemplary base temperature in steady state serial forging. After 1,000 cycles, the tool wear conditions are analysed optically and through destructive microstructure analysis to characterise the effect of the temperature management on the deterioration mechanisms. The results show a significant impact of subsurface temperature control on the wear mechanisms of forging dies. Abrasive wear can be limited to a minimum through internal cooling with major reduction in thermal loads. Increased base temperatures reduce run-in time but increase abrasion.
摘要。增材制造（AM）领域的最新进展使激光粉末床熔融（L-PBF）技术得以在高负荷条件下用于工具钢。因此，减材制造无法实现的内部冷却通道等设计元素可用于热锻模具的功能化和优化。热控制对热锻模具至关重要，因为模具的性能和耐久性在很大程度上取决于锻造过程中表面区域的热量输入和散失。之前的研究[1]开发了一种改进型锻造工具，通过混合 L-PBF 制造工艺产生保形内部冷却通道。本研究的目标是通过实验评估新型工具概念中的保形温度控制对锻造条件下与温度相关的工具劣化机制的影响。主动控制的水温在室温（最大冷却温度）和 180 °C 之间变化，180 °C 代表稳态连续锻造中的示例基准温度。经过 1,000 次循环后，通过光学分析和破坏性微结构分析对工具磨损状况进行分析，以确定温度管理对劣化机制的影响。结果表明，表面下温度控制对锻造模具的磨损机制有重大影响。通过内部冷却可将磨料磨损限制到最低程度，同时大大降低热负荷。基础温度升高会缩短磨合时间，但会增加磨损。
{"title":"Potential of near-surface temperature regulation in hybrid additive manufactured forging dies","authors":"J. Peddinghaus","doi":"10.21741/9781644903131-97","DOIUrl":"https://doi.org/10.21741/9781644903131-97","url":null,"abstract":"Abstract. Recent advances in the field of additive manufacturing (AM) have enabled the utilisation of Laser Powder Bed Fusion (L-PBF) for tool steels under high load conditions. Design elements, such as internal cooling channels, which are not achievable through subtractive manufacturing can therefore be used to functionalise and optimise hot forging tools. Thermal control is crucial for hot forging dies as the performance and endurance of the tools is highly dependent on the input and dissipation of heat in the surface zone during forging. A modified forging tool with conformal internal cooling channels generated through a hybrid L-PBF manufacturing process was developed in prior work [1]. The objective in the presented research is the experimental evaluation of the effect of conformal temperature control in the novel tool concept on the temperature dependent tool deterioration mechanisms in forging conditions. The actively controlled water temperature was varied between room temperature for maximum cooling and 180 °C, representing an exemplary base temperature in steady state serial forging. After 1,000 cycles, the tool wear conditions are analysed optically and through destructive microstructure analysis to characterise the effect of the temperature management on the deterioration mechanisms. The results show a significant impact of subsurface temperature control on the wear mechanisms of forging dies. Abrasive wear can be limited to a minimum through internal cooling with major reduction in thermal loads. Increased base temperatures reduce run-in time but increase abrasion.","PeriodicalId":515987,"journal":{"name":"Materials Research Proceedings","volume":"45 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140975578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-15DOI: 10.21741/9781644903131-51
Johannes Mitsch
Abstract. To predict manufacturing effects in the thermoforming process for fiber reinforced plastics the Finite Element Method is widely used. Most macroscopic simulation methods are based on conventional two-dimensional shell elements which are not capable of modeling the material behavior in thickness direction using constitutive equations. At the same time, standard three-dimensional element formulations are not suitable for the forming simulation of thin textiles due to numerical locking phenomena and the lack of a possible membrane-bending-decoupling. Previous studies focused on a specialized solid-shell element formulation which provides anisotropic but purely elastic material modeling. Since purely elastic approaches cannot accurately describe the deformation behavior in the thermoforming process, the provided element formulation is enhanced to rate-dependent viscoelastic material modeling. Numerical studies are carried out that reveal that the membrane-bending-decoupling is preserved for the viscoelastic material model. Virtual coupon tests demonstrate the rate-dependent material behavior in the solid-shell element. The obtained results show that the general approach of the viscoelastic material behavior within the solid-shell element is suitable to address out-of-plane phenomena in thermoforming simulations.
{"title":"Considering the viscoelastic material behavior in a solid-shell element for thermoforming simulation","authors":"Johannes Mitsch","doi":"10.21741/9781644903131-51","DOIUrl":"https://doi.org/10.21741/9781644903131-51","url":null,"abstract":"Abstract. To predict manufacturing effects in the thermoforming process for fiber reinforced plastics the Finite Element Method is widely used. Most macroscopic simulation methods are based on conventional two-dimensional shell elements which are not capable of modeling the material behavior in thickness direction using constitutive equations. At the same time, standard three-dimensional element formulations are not suitable for the forming simulation of thin textiles due to numerical locking phenomena and the lack of a possible membrane-bending-decoupling. Previous studies focused on a specialized solid-shell element formulation which provides anisotropic but purely elastic material modeling. Since purely elastic approaches cannot accurately describe the deformation behavior in the thermoforming process, the provided element formulation is enhanced to rate-dependent viscoelastic material modeling. Numerical studies are carried out that reveal that the membrane-bending-decoupling is preserved for the viscoelastic material model. Virtual coupon tests demonstrate the rate-dependent material behavior in the solid-shell element. The obtained results show that the general approach of the viscoelastic material behavior within the solid-shell element is suitable to address out-of-plane phenomena in thermoforming simulations.","PeriodicalId":515987,"journal":{"name":"Materials Research Proceedings","volume":"44 20","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140975749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-15DOI: 10.21741/9781644903131-134
L. Grifé
Abstract. The present work investigates the influence of pre-strain on the fracture toughness of 3rd Generation Advanced High Strength Steels (AHSS). Specifically, a Carbide Free Bainitic (CFB) and a Quenching and Partitioning (Q&P) steel have been studied, the properties of which are crucial for lightweight vehicle construction. Fracture toughness, which is a key parameter for crash performance applications, is assessed using the Essential Work of Fracture methodology. The study investigates the pre-straining states of uniaxial tension, plane strain, and equibiaxial tension in 1.5 mm Q&P and 1.4 mm CFB sheet-form steels of 1180 MPa tensile strength. Overall, Q&P steel demonstrates superior fracture toughness compared to CFB steel. Remarkably, the specific essential work of fracture (we) remains unaffected by pre-straining across different strain states. Nevertheless, pre-straining exerts a notable influence on the non-essential plastic work (βwp) due to the plastic energy consumed during pre-deformation. These results suggest that pre-strain has little or no influence on the fracture properties of AHSS, which is relevant for the design and manufacturing of high crash-performance and safety-related components.
{"title":"Influence of pre-strain on fracture toughness of 3rd generation advanced high strength steels","authors":"L. Grifé","doi":"10.21741/9781644903131-134","DOIUrl":"https://doi.org/10.21741/9781644903131-134","url":null,"abstract":"Abstract. The present work investigates the influence of pre-strain on the fracture toughness of 3rd Generation Advanced High Strength Steels (AHSS). Specifically, a Carbide Free Bainitic (CFB) and a Quenching and Partitioning (Q&P) steel have been studied, the properties of which are crucial for lightweight vehicle construction. Fracture toughness, which is a key parameter for crash performance applications, is assessed using the Essential Work of Fracture methodology. The study investigates the pre-straining states of uniaxial tension, plane strain, and equibiaxial tension in 1.5 mm Q&P and 1.4 mm CFB sheet-form steels of 1180 MPa tensile strength. Overall, Q&P steel demonstrates superior fracture toughness compared to CFB steel. Remarkably, the specific essential work of fracture (we) remains unaffected by pre-straining across different strain states. Nevertheless, pre-straining exerts a notable influence on the non-essential plastic work (βwp) due to the plastic energy consumed during pre-deformation. These results suggest that pre-strain has little or no influence on the fracture properties of AHSS, which is relevant for the design and manufacturing of high crash-performance and safety-related components.","PeriodicalId":515987,"journal":{"name":"Materials Research Proceedings","volume":"121 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140977452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-15DOI: 10.21741/9781644903131-234
Lorenz Maier
Abstract. Understanding the strain rate sensitivity of materials is essential for predicting their behavior in sheet metal forming. While uniaxial tension tests are state of the art in characterizing this sensitivity, the deformation response of materials under different loading conditions can significantly deviate from uniaxial behavior. This paper presents a comprehensive study of the strain rate sensitivity of DC04 through a series of experimental investigations with different strain rates. In addition to uniaxial tension tests, the study investigates the strain rate sensitivity under shear and plane strain tests, providing a comprehensive analysis of strain rate sensitivity across different loading scenarios. The investigation aims to understand how the material responds to varying deformation rates, focusing on characterizing their deformation behavior under various loading conditions. The authors collected experimental data from the material with a DIC system. They analyzed it to derive material-specific parameters that describe their strain rate-dependent responses depending on the stress state. To explain this, the authors calibrated three models: Johnson Cook, Cowper Symonds, and Huh Kang.
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