scholarly journals Strength of self-piercing riveted Joints with conventional Rivets and Rivets made of High Nitrogen Steel

2021 ◽  
Author(s):  
Benedikt Uhe ◽  
Clara-Maria Kuball ◽  
Marion Merklein ◽  
Gerson Meschut
Keyword(s):  
Stainless Steel ◽  
Joint Strength ◽  
Lightweight Design ◽  
High Strength ◽  
High Nitrogen Steel ◽  
High Nitrogen ◽  
Forming Process ◽  
Cold Forming ◽  
Local Strength ◽  
Nitrogen Steel

The use of high-strength steel and aluminium is rising due to the intensified efforts being made in lightweight design, and self-piercing riveting is becoming increasingly important. Conventional rivets for self-piercing riveting differ in their geometry, the material used, the condition of the material and the coating. To shorten the manufacturing process, the use of stainless steel with high strain hardening as the rivet material represents a promising approach. This allows the coating of the rivets to be omitted due to the corrosion resistance of the material and, since the strength of the stainless steel is achieved by cold forming, heat treatment is no longer required. In addition, it is possible to adjust the local strength within the rivet. Because of that, the authors have elaborated a concept for using high nitrogen steel 1.3815 as the rivet material. The present investigation focusses on the joint strength in order to evaluate the capability of rivets in high nitrogen steel by comparison to conventional rivets made of treatable steel. Due to certain challenges in the forming process of the high nitrogen steel rivets, deviations result from the targeted rivet geometry. Mainly these deviations cause a lower joint strength with these rivets, which is, however, adequate. All in all, the capability of the new rivet is proven by the results of this investigation.

Process-adapted temperature application within a two-stage rivet forming process for high nitrogen steel

2022 ◽  
pp. 146442072110686
Author(s):  
C-M Kuball ◽  
B Uhe ◽  
G Meschut ◽  
M Merklein
Keyword(s):  
Room Temperature ◽  
Temperature Management ◽  
High Nitrogen Steel ◽  
High Nitrogen ◽  
Forming Process ◽  
Two Stage ◽  
Nitrogen Steel ◽  
Temperature Application ◽  
Stage 1 ◽  
Forming Behaviour

Mechanical joining technologies like self-piercing riveting are gaining importance with regard to environmental protection, as they enable multi-material design and lightweight construction. A new approach is the use of high nitrogen steel as rivet material, which allows to omit the usually necessary heat treatment and coating and thus leads to a shortening of the process chain. Due to the high strain hardening, however, high tool loads must be expected. Thus, appropriate forming strategies are needed. Within this contribution, the influence of applying different temperatures for each forming stage in a two-stage rivet forming process using the high nitrogen steel 1.3815 is investigated. The findings provide a basic understanding of the influence of the temperature management when forming high nitrogen steel. For this purpose, the rivets are not formed at the same temperature in each stage, but an elevated temperature is applied selectively. Different process routes are investigated. First, cups are manufactured in stage 1 at room temperature, followed by stage 2 at 200°C. Second, cups are formed in stage 1 at 200°C and used for stage 2 at room temperature. By comparing the findings with results when applying the same temperature in both stages, it is shown that the temperature during the first forming operation has an effect on the forming behaviour during the second forming stage. The required forming forces and the resulting rivet hardness can be influenced by process-adapted temperature application. Furthermore, the causes for the temperature impact on the residual cup thickness in stage 1 are evaluated by a cause and effect analysis, which provides a deeper process understanding. The thermal expansion of the tool and the billet as well as the improved forming behaviour at 200°C are identified as the main influencing causes on the achieved residual cup thickness.

Structure Characterization of Fe-21Cr-17Mn-2Mo-Nb-0.83N Alloy Processed by Surface Mechanical Nanocrystallization

2014 ◽  
Vol 886 ◽  
pp. 115-118
Author(s):  
Chang Tao Ji ◽  
Jing Jing Huo ◽  
Xiao Peng Cui ◽  
Zi Wei Chen
Keyword(s):  
Surface Concentration ◽  
Rolling Bearing ◽  
Structure Characterization ◽  
High Nitrogen Steel ◽  
High Nitrogen ◽  
Forming Process ◽  
Nitrogen Steel ◽  
Deformed Layer ◽  
Austenite Grains

A friction head with an embedded rolling bearing was designed, by which Fe-21Cr-17Mn-2.43Mo-Nb-0.83N high nitrogen steel was ground under rotating pressure. It was indicated that the forming process of surface nanometer grain included surface concentration plastic slip, twins deformation and fining, fragmentation and recrystallization of primary austenite grains. The plastically deformed layer is about 300μm. The surface grain is nanosize, and the grain size is about 10nm to 20nm.

scholarly journals ALUMINOBAROTHERMIC SYNTHESIS OF HIGH-NITROGEN STEEL

2019 ◽  
Vol 62 (2) ◽  
pp. 154-162
Author(s):  
V. I. Lad’yanov ◽  
G. A. Dorofeev ◽  
E. V. Kuz’minykh ◽  
V. A. Karev ◽  
A. N. Lubnin
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
Correct Choice ◽  
Nitrogen Pressure ◽  
Lattice Parameter ◽  
Austenitic Steels ◽  
High Nitrogen Steel ◽  
High Nitrogen ◽  
Quenching Temperature ◽  
Nitrogen Steel

High-nitrogen austenitic steels are promising materials, combining high strength, plasticity and corrosion resistance properties. However, to produce high-nitrogen steel by conventional metallurgical methods under high nitrogen pressure, powerful and complex metallurgical equipment is required. From energy-saving viewpoint, an alternative and simpler method for producing high-nitrogen steels can be aluminothermy (reduction of metal oxides by metallic aluminum) under nitrogen pressure. Thermodynamic modeling of aluminothermic reactions in a nitrogen atmosphere was carried out by the authors. Aluminothermy under nitrogen pressure was used to produce high-nitrogen nickel-free Cr – N and Cr – Mn – N stainless steels with a nitrogen content of about 1  %. Microstructure (X-ray diffraction, metallography and transmission electron microscopy techniques) and mechanical properties were examined. Thermodynamic analysis has shown that the aluminothermic reduction reactions do not go to the end. The most important parameter of the synthesis is the ratio of Al and oxygen in the charge, the correct choice of which provides a compromise between completeness of oxides reduction, content of aluminum and oxygen in steel (the degree of deoxidation), and its contamination with aluminum nitride. Cr – N steel ingots in the cast state had the structure of nitrogen perlite (ferrite-nitride mixture), and Cr – Mn – N steel – ferrite-austenite structure with attributes of austenite discontinuous decomposition with Cr2 N precipitations. Quenching resulted in complete austenization of both steels. The compliance of the austenite lattice parameter obtained from the diffractograms for quenched Cr – Mn – N steel with the parameter predicted from the known concentration dependence for Cr – Mn – N austenitic steels indicated that all alloying elements (including nitrogen) were dissolved in austenite during aging at quenching temperature and fixed in the solid solution by quenching. Study of the mechanical properties of quenched Cr – Mn – N steel has shown a combination of high strength and ductility. It is concluded that by the aluminothermic method a high-nitrogen steel can be obtained, which, by mechanical properties, is not inferior to industrial steel  – analog manufacted by electroslag remelting under nitrogen pressure.

scholarly journals Dynamic Mechanical Properties of High Nitrogen Steel under Combined Loading

2021 ◽  
Vol 1855 (1) ◽  
pp. 012009
Author(s):  
Zizhen Yang ◽  
Cheng Miao ◽  
Hailing Wu ◽  
Tao Zhong ◽  
Lihong Bai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Dynamic Mechanical Properties ◽  
Combined Loading ◽  
High Nitrogen Steel ◽  
High Nitrogen ◽  
Dynamic Mechanical ◽  
Nitrogen Steel

Peculiarities of tensile deformation and fracture of high-nitrogen steel obtained by electron beam additive manufacturing

2020 ◽  
Author(s):  
Sergey V. Astafurov ◽  
Elena G. Astafurova ◽  
Kseniya A. Reunova ◽  
Evgenii V. Melnikov ◽  
Marina Yu. Panchenko ◽  
...  
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Tensile Deformation ◽  
High Nitrogen Steel ◽  
High Nitrogen ◽  
Deformation And Fracture ◽  
Nitrogen Steel

Research of Flow Simulation with High-Pressure and Bottom-Blowing Nitrogen

2013 ◽  
Vol 634-638 ◽  
pp. 3110-3113
Author(s):  
Shu Huan Wang ◽  
He Jun Zhang ◽  
Ding Guo Zhao
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Molten Steel ◽  
Gas Content ◽  
High Nitrogen Steel ◽  
High Nitrogen ◽  
Nitrogen Steel ◽  
Bottom Blowing ◽  
Steel Flow ◽  
Pressure Factor

According to the actual situation of refining high nitrogen steel with the laboratory high pressure reaction axe, the molten steel flow field in the high-pressure and bottom-blowing nitrogen reactor was simulated by using the software Fluent. The rules of the influence of pressure factor on the molten steel flow field characteristics, turbulent kinetic energy and gas content were explored. According to the characteristics of the flow field and gas-liquid two phase structure, the rules of the influence of pressure factor on nitrogen concentration distribution were analyzed. So some useful theoretical basis and guidance were provided for laboratory refining high nitrogen steel and industrial production in the future.

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