scholarly journals Case Study on Large Ingots Cracking Failure

2021 ◽  
Author(s):  
S M Nazmuz Sakib
Keyword(s):  
High Strength ◽  
Literature Study ◽  
Test Procedures ◽  
Energy Dispersion Spectroscopy ◽  
Optical Scanning ◽  
Forging Process ◽  
Electron Microscopies ◽  
Large Size ◽  
Study Test ◽  
Open Die Forging

Use of Metal and its alloys have become the need of this world. high strength pipes and equipment are required for the extraction of bituminous oil from soil. For this High strength Low Alloy Steel (Micro-alloyed steels) can be used. HSLA required large size ingots for its manufacturing therefore in recent years, large size ingots demand is increased. Large size ingots are subjected to cracking while manufacturing during open die forging process. Optical Scanning Electron Microscopies and Energy dispersion Spectroscopy techniques are carried out for the investigation of root causes of the cracking during forging of large size ingots. Microstructure of large size ingots sample are reviewed at different locations and grain boundaries. Results of these chemical techniques shows the enrichment of chromium and oxygen content at the boundaries which clearly differentiated a cracked boundary and non-cracked locations. This writing comprises the literature study, test procedures and analyzing the results to review that abnormal grain growth was the cause of cracking of large size ingots during forging process. The report also reviewed, alternate heat treatments and possible solution.

scholarly journals Analysis of Void Closure during Open Die Forging Process of Large Size Steel Ingots

2016 ◽  
Vol 716 ◽  
pp. 579-585 ◽  
Author(s):  
Nathan Harris ◽  
Davood Shahriari ◽  
Mohammad Jahazi
Keyword(s):  
Strain Rate ◽  
High Strength Steel ◽  
Volumetric Strain ◽  
High Strength ◽  
Material Model ◽  
Void Closure ◽  
Forging Process ◽  
Large Size ◽  
Die Forging ◽  
Open Die Forging

Large size forged ingots, made of high strength steel, are widely used in aerospace, transport and energy applications. The presence of internal voids in the as-cast ingot may significantly affect the mechanical properties of final products. Thus, such internal defects must be eliminated during first steps of the open die forging process. In this paper, the effect of in-billet void positioning on void closure throughout the ingot breakdown process and specifically the upsetting step in a large ingot size steel is quantitatively investigated. The developed Hansel-Spittel material model for new high strength steel is used in this study. The ingot forging process (3D simulation) was simulated with Forge NxT 1.0® according to existing industrial data. A degree of closure of ten virtual existing voids was evaluated using a semi-analytical void closure model. It is found that the upsetting process is most effective for void closure in core regions and central upper billet including certain areas within the dead metal zone (DMZ). The volumetric strain rate is determined and two types of inertial effects are observed. The dependence of void closure on accumulated equivalent deformation is calculated and discussed in relation to void in-billet locations. The original combination of information from both relative void closure and the volumetric strain rate provides a way to optimize the forging process in terms of void elimination.

Characterization of inclusions and second-phase particles in high-Mn TWIP steels microalloyed with Ti, Ti/B, Nb, V and Mo, in as-solutioned condition

MRS Advances ◽  
2020 ◽  
Vol 5 (59-60) ◽  
pp. 3023-3033
Author(s):  
D. Mijangos ◽  
I. Mejía ◽  
J. M. Cabrera
Keyword(s):  
Mechanical Properties ◽  
Research Work ◽  
High Strength ◽  
Second Phase ◽  
Energy Dispersion Spectroscopy ◽  
Austenitic Phase ◽  
Electron Microscopies ◽  
Second Phase Particles ◽  
Twip Steels ◽  
Microalloying Elements

AbstractIn recent years there has been an increase in the field of research of advanced steels that have excellent mechanical properties combining high strength with excellent ductility. Within this range of advanced steels are the stable austenitic phase steels at room temperature of twinning induced plasticity known as TWIP. An important aspect to highlight about TWIP steels is their addition with different microalloying elements, generally less than 0.20 wt. %, which are forming precipitated phases such as carbides, nitrides and carbonitrides, and directly or indirectly control and/or modify microstructure and mechanical properties in these steels. Microalloying elements can cause a higher degree of hardening due to the formation of precipitates and grain refinement. The present research work studies the inclusions and second-phase particles formed in Fe–21Mn–1.3Si–1.6Al TWIP steels microalloyed with Ti, Nb, V, Mo and Ti/B in as-solution condition. TWIP steels melted in induction furnace were homogenized and hot-rolled at 1200 °C with reduction of 60 %. Subsequently, rolled plates were solubilized at 1100 °C followed by water quench. Thermodynamics-based predictions of inclusions and second-phases of different TWIP steels were carried out using JMatPro®V.9.1.2. Metallographic characterization was carried out by light optical and scanning electron microscopies (LOM, SEM), while second-phase particles characterization was performed using energy dispersion spectroscopy (SEM-EDS). Also, Vickers microhardness tests were carried out in accordance to ASTM E92 standard. In general, results showed the formation of inclusions of AlN and MnS at higher temperatures, which act as nuclei points for the precipitation particles of each type of microalloying element (TiN, TiC, Nb (C, N), VC and MoC) at lower temperatures. The studied TWIP steels exhibit similar microhardness values, since the microalloying elements are mostly dissolved in solid solution. The TWIP steels microalloyed with V and Ti exhibited the highest microhardness values.

Subsurface Crack Initiation and Propagation in an Open Dieforged High Strength Steel: A Microstructural Analysis

2021 ◽  
Vol 880 ◽  
pp. 29-34
Author(s):  
Abdelhalim Loucif ◽  
Jean Benoit Morin ◽  
Louis Philippe Lapierre-Boire ◽  
Mohammad Jahazi
Keyword(s):  
Crack Initiation ◽  
Microstructural Analysis ◽  
High Strength ◽  
Damage Analysis ◽  
Crack Initiation And Propagation ◽  
Medium Carbon ◽  
Large Size ◽  
Initiation And Propagation ◽  
Open Die Forging ◽  
Manganese Chromium

This paper presents an experimental investigation with the objective to determine the root causes for the cracking of a large size bar made of a medium carbon low alloy steel after open die forging and heat treatments operations. The cracks were observed below the surface during the machining step. In order to understand the mechanisms of crack initiation and propagation, micro-CT tomography and scanning electron microscope (SEM) were employed. Microstructural damage analysis revealed oxidation of different alloying elements, more specifically manganese, chromium and silicon. The presence of defects in the form of cavities and porosities were also observed at the grain boundaries. Some of the above defects were observed along the crack path, while others were on both sides of the cracks without any connection to them and finally, a third group completely isolated from any crack. The characteristics of the defects were thoroughly analyzed and it was found that the crack initiation could be attributed principally to the porosities/cavities formed during solidification. The analysis also showed that crack propagation occurred during solidification and/or forging and heat treatment steps.

scholarly journals Hot Deformation Behavior and Dynamic Recrystallization of Ultra High Strength Steel

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1239
Author(s):  
Liping Zhong ◽  
Bo Wang ◽  
Chundong Hu ◽  
Jieyu Zhang ◽  
Yu Yao
Keyword(s):  
Martensitic Steel ◽  
High Strength ◽  
Experimental Results ◽  
Hot Deformation Behavior ◽  
Thermal Compression ◽  
Forging Process ◽  
Finite Element Software ◽  
Ultra High Strength Steel ◽  
Recrystallized Grain Size ◽  
Deform 3D

In this paper, in order to improve the microstructure uniformity of an ultra-high strength martensitic steel with a strength greater than 2500 MPa developed by multi-directional forging in the laboratory, a single-pass hot compression experiment with the strain rate of 0.01 to 1 s−1 and a temperature of 800 to 1150 °C was conducted. Based on the experimental data, the material parameters were determined, the constitutive model considering the influence of work hardening, the recrystallization softening on the dislocation density, and the recrystallized grain size model were established. After introducing the model into the finite element software DEFORM-3D, the thermal compression experiment was simulated, and the results were consistent with the experimental results. The rule for obtaining forging stock with a uniform and refinement microstructure was acquired by comparing the simulation and the experimental results, which are helpful to formulate an appropriate forging process.

scholarly journals Multi-Stage Cold Forging Process for Manufacturing a High-Strength One-Body Input Shaft

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 532
Author(s):  
A Jo ◽  
Myeong Jeong ◽  
Sang Lee ◽  
Young Moon ◽  
Sun Hwang
Keyword(s):  
High Strength ◽  
Microstructural Characterization ◽  
Fatigue Tests ◽  
Machining Process ◽  
Cold Forging ◽  
Element Analysis ◽  
Forging Process ◽  
Input Shaft ◽  
Multi Stage ◽  
The One

A multi-stage cold forging process was developed and complemented with finite element analysis (FEA) to manufacture a high-strength one-body input shaft with a long length body and no separate parts. FEA showed that the one-body input shaft was manufactured without any defects or fractures. Experiments, such as tensile, hardness, torsion, and fatigue tests, and microstructural characterization, were performed to compare the properties of the input shaft produced by the proposed method with those produced using the machining process. The ultimate tensile strength showed a 50% increase and the torque showed a 100 Nm increase, confirming that the input shaft manufactured using the proposed process is superior to that processed using the machining process. Thus, this study provides a proof-of-concept for the design and development of a multi-stage cold forging process to manufacture a one-body input shaft with improved mechanical properties and material recovery rate.

Physical Simulation of Weldability of Weldox 1300 Steel

2013 ◽  
Vol 762 ◽  
pp. 551-555 ◽  
Author(s):  
Marek Stanislaw Węglowski ◽  
Marian Zeman ◽  
Miroslaw Lomozik
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Physical Simulation ◽  
High Strength ◽  
Parent Material ◽  
Cooling Time ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Transformation Diagrams ◽  
The Impact

In the present study, the investigation of weldability of new ultra-high strength - Weldox 1300 steel has been presented. The thermal simulated samples were used to investigate the effect of welding cooling time t8/5 on the microstructure and mechanical properties of the heat affected zone (HAZ). In the frame of these investigation the microstructure was studied by the light (LM) and transmission electron microscopies (TEM). It has been shown that the microstructure of the Weldox 1300 steel is composed of tempered martensite, and inside the laths the minor precipitations mainly V(CN) and molybdenum carbide Mo2C were observed. Mechanical properties of parent material were analysed by the tensile, impact and hardness tests. In details the influence of cooling time in the range of 2,5 - 300 s. on hardness, impact toughness and microstructure of simulated HAZ was studied by using welding thermal simulation test. The results show that the impact toughness and hardness decrease with the increase of t8/5 under the condition of a single thermal cycle in simulated HAZ. The continuous cooling transformation diagrams (CCT-W for welding conditions) of Weldox 1300 steel for welding purposes was also elaborated. The steel Weldox 1300 for cooling time in the range of 2,5 - 4 s showed martensite microstructure, for time from 4 s to 60 s mixture of martensite and bainite, and for longer cooling time mixture of ferrite, bainite and martensite. The results indicated that the weldability of Weldox 1300 steel is limited and to avoid the cold cracking the preheating procedure or medium net linear heat input should be used.

Application of Large Size and High Strength Angle in UHV Transmission Line Tower

2014 ◽  
Vol 680 ◽  
pp. 418-421
Author(s):  
Feng Lin Gan ◽  
Xin Wang
Keyword(s):  
Transmission Line ◽  
Axial Stress ◽  
High Strength ◽  
Additional Stress ◽  
Large Size ◽  
Section Area ◽  
Stiffness Variation ◽  
Large Width ◽  
Angle Steel ◽  
Normal Angle

Considering width and thickness of large width angle steel, the section area of large width angle steel is larger than that of normal angle steel. Application of large width angle can increase bearing capacity of the member. Therefore it is feasible that large width angle steel replaces double combined angle steels. Taking the tower for ±800 kV DC transmission line from Jin ping to south Jiangsu Province, under the same design conditions, large width angle steel and double combined angle steels are used respectively in the main members of the tower to modeling finite element analysis.The results indicate that the stiffness variation is more uniform, causing rod end bending bar additional stress is about the axial stress of about 2%~3%.

Fully Coupled Finite Element Analysis of an Automatic Multi-Stage Cold Forging Process

2020 ◽  
Vol 311 ◽  
pp. 88-93
Author(s):  
Jong Bok Byun ◽  
Hyun Joon Lee ◽  
Jong Bok Park ◽  
Il Dong Seo ◽  
Man Soo Joun
Keyword(s):  
High Strength ◽  
Material Model ◽  
Die Design ◽  
Cold Forging ◽  
Complete Analysis ◽  
Analysis Model ◽  
Element Analysis ◽  
Forging Process ◽  
Multi Stage ◽  
Analysis Scheme

In this paper, non-isothermal analysis of an automatic multi-stage cold forging process of a ball-stud is conducted using a new material model which is a closed form function of strain, temperature and strain rate covering low and warm temperatures for high-strength stainless steel SUS304. An assembled die structural analysis scheme is employed for revealing the detailed die stresses, which is of great importance for process and die design for metal forming of the materials with high strengths. Die elastic deformation is dealt with to predict final geometries of material with higher accuracy. A complete analysis model is proposed to be used for optimal design of process and die designs in automatic multi-stage cold forging of high-strength materials.

scholarly journals Ageing of Adhesive Joints for Façade Applications – Comparison of Artificial and Real Weathering Conditions

2019 ◽  
Vol 279 ◽  
pp. 02013 ◽  
Author(s):  
Barbora Nečasová ◽  
Pavel Liška ◽  
Michal Novotný
Keyword(s):  
High Strength ◽  
Weather Conditions ◽  
Adhesive Joints ◽  
Laboratory Measurements ◽  
Adhesive Systems ◽  
Test Procedures ◽  
Technical Standards ◽  
Specific Test ◽  
Mechanical Joints ◽  
Heavy Loads

Currently, the adhesive joints are more and more regularly used as an alternative to mechanical joints. They often offer a more suitable, durable and faster possibility. They provide a solution with a more even distribution of stresses in the joint, which consequently allows an increase in the rigidity of the structure and allows it to withstand even heavy loads. High - strength flexible adhesive systems enable the implementation of effective structural joints, and although several decades have passed since the certification and installation of the first façade system with bonded anchoring, even today it is not a matter that is properly grounded in technical standards. A list of specific test procedures on whose basis the behaviour of the joint over the next 40 years could be predicted does not exist. On the basis of these facts, the authors have decided to subject the test samples both to laboratory measurements, where two methods were selected, as well as to expose them to the effects of real weather conditions for a 3-year period. Comparison of the real environment influence results and the methods of artificial aging showed that the selected conditioning methods adequately simulate the effects of weather conditions.

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