scholarly journals Influence of degree of deformation on welding pore reduction in high-carbon steels

2021 ◽  
Vol 15 (2) ◽  
pp. 161-168
Author(s):  
Bernd-Arno Behrens ◽  
Hans Jürgen Maier ◽  
Gerhard Poll ◽  
Ludger Overmeyer ◽  
Hendrik Wester ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Base Material ◽  
Carbon Steels ◽  
Intermediate Zone ◽  
Acoustic Microscopy ◽  
Uniaxial Compression Test ◽  
Forming Process ◽  
Degree Of Deformation ◽  
Welding Processes ◽  
Homogeneous Temperature

AbstractLocally adapted properties within a machine component offer opportunities to increase the performance of a component by using high strenght materials where they are needed. The economic production of such hybrid components on the other hand represents a major challenge. The new tailored forming process chain, which is developed within the collaborative research center (CRC 1153) represents a possible solution to produce hybrid components. This is made possible by the use of pre-joined hybrid semi-finished products made from two different steel alloys, which are subsequently formed. The semi-finished products can be manufactured for example by means of deposition welding. Due to a thermal mechanical treatment, an overall higher component strength of the joining zone can be achieved. The deposition welding processes can be used to generate a cladding on a base material. During the welding, one of the most difficult tasks is to reduce the amount and size of pores in the joining zone. These pores can reduce the strength in the joining zone of the welded parts. However, additional pores can occur in the intermediate zone between the substrate and the cladding. In the presented study, the influence of the forming process on the closing of pores in the cladding and in the intermediate zone was investigated. Therefore, cylindrical specimen were extracted in longitudinal direction of the welding track by wire-cut eroding. These welding tracks are manufactured by plasma-transferred arc welding of AISI 52100 on a base plate made of AISI 1015. Further, specimens were prepared transversely, so that the base material, the intermediate layer, and the welded material are axially arranged in the specimen. The prepared specimen were checked for pores by means of scanning acoustic microscopy. Subsequently, an uniaxial compression test was carried out with various degrees of deformation and the two specimen designs were examined again for pores. A microstructure analysis was carried out after each step. The investigations show that there is a need for a minimum degree of deformation to reduce pores in the welded material. However, this required plastic strain cannot be achieved in the welded material of the hybrid specimen, which is a result of the homogeneous temperature distribution in the specimen. The homogeneous temperature distribution leads to different flow properties in the specimen, which means that the main plastic deformation is taking place in the base material.

Study on Forming Behaviour of Friction Stir Welded Blanks During Single Point Incremental Forming (SPIF) Process

2020 ◽  
Author(s):  
Shalin Marathe ◽  
Harit Raval
Keyword(s):  
Friction Stir Welding ◽  
Incremental Forming ◽  
Single Point ◽  
Base Material ◽  
Forming Limit ◽  
Single Point Incremental Forming ◽  
Cnc Milling ◽  
Forming Process ◽  
Friction Stir ◽  
Welding Processes

Abstract The automobile, transportation and shipbuilding industries are aiming at fuel efficient products. In order to enhance the fuel efficiency, the overall weight of the product should be brought down. This requirement has increased the use of material like aluminium and its alloys. But, it is difficult to weld aluminium using conventional welding processes. This problem can be solved by inventions like friction stir welding (FSW) process. During fabrication of product, FSW joints are subjected to many different processes and forming is one of them. During conventional forming, the formability of the welded blanks is found to be lower than the formability of the parent blank involved in it. One of the major reasons for reduction in formability is the global deformation provided on the blank during forming process. In order to improve the formability of homogeneous blanks, Single Point Incremental Forming (SPIF) is found to be giving excellent results. So, in this work formability of the welded blanks is investigated during the SPIF process. Friction Stir Welding is used to fabricate the welded blanks using AA 6061 T6 as base material. Welded blanks are formed in to truncated cone through SPIF process. CNC milling machine is used as SPIF machine tool to perform the experimental work. In order to avoid direct contact between weld seam and forming tool, a dummy sheet was used between them. As responses forming limit curve (FLC), surface roughness, and thinning are investigated. It was found that use of dummy sheet leads to improve the surface finish of the formed blank. The formability of the blank was found less in comparison to the parent metal involved in it. Uneven distribution of mechanical properties in the welded blanks leads to decrease the formability of the welded blanks.

Microstructure of resistance spot welding of maraging steels

1990 ◽  
Vol 48 (4) ◽  
pp. 900-901
Author(s):  
I. Neuman ◽  
S.F. Dirnfeld ◽  
I. Minkoff
Keyword(s):  
Maraging Steel ◽  
Spot Welding ◽  
Lath Martensite ◽  
Base Material ◽  
Aging Treatment ◽  
High Strength ◽  
Maraging Steels ◽  
Heat Treated ◽  
Current Cycle ◽  
Welding Processes

Experimental work on the spot welding of Maraging Steels revealed a surprisingly low level of strength - both in the as welded and in aged conditions. This appeared unusual since in the welding of these materials by other welding processes (TIG,MIG) the strength level is almost that of the base material. The maraging steel C250 investigated had the composition: 18wt%Ni, 8wt%Co, 5wt%Mo and additions of Al and Ti. It has a nominal tensile strength of 250 KSI. The heat treated structure of maraging steel is lath martensite the final high strength is reached by aging treatment at 485°C for 3-4 hours. During the aging process precipitation takes place of Ni3Mo and Ni3Ti and an ordered solid solution containing Co is formed.Three types of spot welding cycles were investigated: multi-pulse current cycle, bi-pulse cycle and single pulsle cycle. TIG welded samples were also tested for comparison.The microstructure investigations were carried out by SEM and EDS as well as by fractography. For multicycle spot welded maraging C250 (without aging), the dendrites start from the fusion line towards the nugget centre with an epitaxial growth region of various widths, as seen in Figure 1.

scholarly journals Development of laser welding of high strength aluminium alloy 2024-T4 with controlled thermal cycle

2020 ◽  
Vol 326 ◽  
pp. 08005
Author(s):  
Mete Demirorer ◽  
Wojciech Suder ◽  
Supriyo Ganguly ◽  
Simon Hogg ◽  
Hassam Naeem
Keyword(s):  
Laser Beam ◽  
Laser Welding ◽  
Heat Input ◽  
Thermal Cycle ◽  
Laser Beam Welding ◽  
Base Material ◽  
High Strength ◽  
Cooling Rates ◽  
Aa 2024 ◽  
Welding Processes

An innovative process design, to avoid thermal degradation during autogenous fusion welding of high strength AA 2024-T4 alloy, based on laser beam welding, is being developed. A series of instrumented laser welds in 2 mm thick AA 2024-T4 alloys were made with different processing conditions resulting in different thermal profiles and cooling rates. The welds were examined under SEM, TEM and LOM, and subjected to micro-hardness examination. This allowed us to understand the influence of cooling rate, peak temperature, and thermal cycle on the growth of precipitates, and related degradation in the weld and heat affected area, evident as softening. Although laser beam welding allows significant reduction of heat input, and higher cooling rates, as compared to other high heat input welding processes, this was found insufficient to completely supress coarsening of precipitate in HAZ. To understand the required range of thermal cycles, additional dilatometry tests were carried out using the same base material to understand the time-temperature relationship of precipitate formation. The results were used to design a novel laser welding process with enhanced cooling, such as with copper backing bar and cryogenic cooling.

Environmental tests of embedded thin- and thick-film resistors in comparison to chip resistors

Circuit World ◽  
2014 ◽  
Vol 40 (1) ◽  
pp. 7-12 ◽  
Author(s):  
Wojciech Steplewski ◽  
Andrzej Dziedzic ◽  
Janusz Borecki ◽  
Grazyna Koziol ◽  
Tomasz Serzysko
Keyword(s):  
Thin Film ◽  
Thick Film ◽  
Electrical Resistance ◽  
Printed Circuit Boards ◽  
Base Material ◽  
Forming Process ◽  
Content Type ◽  
Thin Film Resistors ◽  
Embedded Resistors ◽  
The Impact

Purpose – The purpose of this paper is to investigate the influence of parameters of embedded resistive elements manufacturing process as well as the influence of environmental factors on their electrical resistance. The investigations were made in comparison to the similar constructions of discrete chip resistors assembled to standard printed circuit boards (PCBs). Design/methodology/approach – The investigations were based on the thin-film resistors made of NiP alloy, thick-film resistors made of carbon or carbon-silver inks as well as chip resistors in 0402 and 0603 packages. The polymer thick-film resistive films were screen-printed on the several types finishing materials of contact terminations such as copper, silver, and gold. To determine the sensitivity of embedded resistors versus standard assembled chip resistors on environmental exposure, the climatic chamber was used. The measurements of resistance were carried out periodically during the tests, and after the exposure cycles. Findings – The results show that the change of electrical resistance of embedded resistors, in dependence of construction and base material, is different and mainly not exceed the range of 3 per cent. The achieved results in reference to thin-film resistors are comparable with results for standard chip resistors. However, the results that were obtained for thick-film resistors with Ag and Ni/Au contacts are similar. It was not found the big differences between resistors with and without conformal coating. Research limitations/implications – The studies show that embedded resistors can be used interchangeably with chip resistors. It allows to save the area on the surface of PCB, occupied by these passive elements, for assembly of active elements (ICs) and thus enable to miniaturization of electronic devices. But embedding of passive elements into PCB requires to tackle the effect of each forming process steps on the operational properties. Originality/value – The technique of passive elements embedding into PCB is generally known; however, there are no detailed reports on the impact of individual process steps and environmental conditions on the stability of their electrical resistance. The studies allow to understand the importance of each factor process and the mechanisms of operational properties changes depending on the used materials.

A cylindrical furnace with homogeneous temperature distribution for use in a cubic high‐pressure press

1990 ◽  
Vol 61 (2) ◽  
pp. 830-833 ◽  
Author(s):  
Yasushi Kawashima ◽  
Yoshihiko Tsuchida ◽  
Wataru Utsumi ◽  
Takehiko Yagi
Keyword(s):  
High Pressure ◽  
Temperature Distribution ◽  
Cylindrical Furnace ◽  
Homogeneous Temperature

scholarly journals Catalytic Micro Gas Sensor with Excellent Homogeneous Temperature Distribution and Low Power Consumption for Long-Term Stable Operation

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 927 ◽  
Author(s):  
Anmona Shabnam Pranti ◽  
Daniel Loof ◽  
Sebastian Kunz ◽  
Marcus Bäumer ◽  
Walter Lang
Keyword(s):  
Temperature Distribution ◽  
Low Power ◽  
Gas Sensor ◽  
Gas Flow ◽  
Pt Nanoparticles ◽  
Stable Operation ◽  
Catalytic Layer ◽  
Micro Gas Sensor ◽  
Homogeneous Temperature

This paper presents a long-term stable thermoelectric micro gas sensor with ligand linked Pt nanoparticles as catalyst. The sensor design gives an excellent homogeneous temperature distribution over the catalytic layer, an important factor for long-term stability. The sensor consumes very low power, 18 mW at 100 °C heater temperature. Another thermoresistive sensor is also fabricated with same material for comparative analysis. The thermoelectric sensor gives better temperature homogeneity and consumes 23% less power than thermoresistive sensor for same average temperature on the membrane. The sensor shows linear characteristics with temperature change and has significantly high Seebeck coefficient of 6.5 mV/K. The output of the sensor remains completely constant under 15,000 ppm continuous H2 gas flow for 24 h. No degradation of sensor signal for 24 h indicates no deactivation of catalytic layer over the time. The sensor is tested with 3 different amount of catalyst at 2 different operating temperatures under 6000 ppm and 15,000 ppm continuous H2 gas flow for 4 h. Sensor output is completely stable for 3 different amount of catalyst.

Multiaxial Mechanical Strength of AA-2024-T3 Aluminium Alloy Sheets Joined by Friction Stir Welding Processes

2009 ◽  
Vol 83-86 ◽  
pp. 1243-1250 ◽  
Author(s):  
R.L.L.P. Cerveira ◽  
G. F. Batalha
Keyword(s):  
Friction Stir Welding ◽  
Base Material ◽  
Short Review ◽  
Multiaxial Loading ◽  
Angle Variation ◽  
Friction Stir ◽  
Aa 2024 ◽  
Aeronautical Industry ◽  
Welding Processes ◽  
Joining Process

The aim is to analyze a junction produced by a Friction Stir Welding (FSW) joining process under multiaxial loading, employing a modified Arcan test that allows an angle variation of the loading in order to evaluate the failure of the FSW weldment as compared to the base material. A short review of the earlier studies and relevant theories about the FSW processes and fracture modes I and II under multiaxial loading are presented and were experimentally evaluated for an AA2024-T3 aluminum alloy sheets (t = 1.6 mm) processed by FSW. The results obtained can serve as a basis to compare the junctions made using FSW and conventional joint methods such as rivets (very common practice in the aeronautical industry).

scholarly journals Modelling of hardfacing layers deposition parameters using robust machine learning algorithms

2021 ◽  
Vol 2130 (1) ◽  
pp. 012016
Author(s):  
K Zając ◽  
K Płatek ◽  
P Biskup ◽  
L Łatka
Keyword(s):  
Gas Metal Arc Welding ◽  
Model Performance ◽  
Base Material ◽  
Neural Model ◽  
Machine Learning Algorithms ◽  
Influence Of Process Parameters ◽  
Generic Structure ◽  
Modelling Framework ◽  
Metal Arc Welding ◽  
Welding Processes

Abstract The study presents a data-driven framework for modelling parameters of hardfacing deposits by GMAW using neural models to estimate the influence of process parameters without the need of creating experimental samples of the material and detailed measurements. The process of GAS Metal Arc Welding (GMAW) hardfacing does sometimes create non-homogenous structures in the material not only in deposited material, but also in the heat-affected zone (HAZ) and base material. Those structures are not fully deterministic, so the modelling method should account for this unpredictable component and only learn the generic structure of the hardness of the resulting material. Artificial neural networks (ANN) were used to create a model of the process using only measured samples without any knowledge of equations governing the process. Robust learning was used to decrease the influence of outliers and noise in the measured data on the neural model performance. The proposed method relies on modification of the loss function and several of them are compared and evaluated as an attempt to construct general framework for analysing the hardness as a function of electric current and arc velocity. The proposed method can create robust models of the hardfacing layers deposition or other welding processes and predict the properties of resulting materials even for unseen parameters based on experimental data. This modelling framework is not typically used for metallurgy, and it requires further case studies to verify its generalisability.

scholarly journals Lamé curve approximation for the assessment of the 3D temperature distribution in keyhole mode welding processes

2020 ◽  
Vol 32 (2) ◽  
pp. 022042
Author(s):  
Antoni Artinov ◽  
Victor Karkhin ◽  
Nasim Bakir ◽  
Xiangmeng Meng ◽  
Marcel Bachmann ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Curve Approximation ◽  
Keyhole Mode Welding ◽  
Welding Processes

scholarly journals Numerical Investigation of Air Conditioners’ Control Unit Position On Temperature Distribution and Energy Consumptions of a Room

2019 ◽  
Vol 111 ◽  
pp. 02039
Author(s):  
Mustafa Mutlu ◽  
Emre Çalışkan
Keyword(s):  
Steady State ◽  
Temperature Distribution ◽  
Control Unit ◽  
Air Conditioners ◽  
Comfort Levels ◽  
Temperature Distributions ◽  
Energy Consumptions ◽  
Cooling Loads ◽  
Homogeneous Temperature ◽  
Comfort Criteria

Minimum temperature difference should be achieved in conditioned rooms to meet comfort criteria. It is desired that the temperature set by a user from the control unit, should be the same in the entire room. Therefore, the position of the control unit plays a significant role in order to achieve a homogeneous temperature distribution in the room. In this study, the effect of control unit positioning on temperature and velocity distributions in a room, where a cassette type indoor unit was applied, was numerically investigated. Blowing temperature and speed of the indoor unit has been adjusted by the temperature value that measured by a control unit which was placed at five different locations, in order to examine positioning effects of the control unit. Predicted percentage dissatisfied (PPD) values were calculated, and uncomfortable zones were determined by 2-dimensional analyses. Cooling loads, as well as energy consumptions, were calculated and their variations according to the position of control unit was figured out in steady state conditions. The results showed that control unit positioning not only influences the comfort levels or temperature distributions in a room but also energy consumptions.

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