جوشکاری اصطکاکی لحظه ای (IFW) برای کاربردهای هوافضا

 Inertia friction welding (IFW) for aerospace applications

جوشکاری اصطکاکی لحظه ای  (IFW) برای کاربردهای هوافضا

ABSTRACT

The use of inertia welding in the aerospace industry has been steadily increasing owing to the signifi cant improvements it provides in joint quality, compared with the use of fusion welding. This chapter introduces the process, with respect to its operation, parameters, differences from other friction welding techniques and equipment. It also explains the application of the technique and the selection of the process parameters, and the different mathematical, analytical and numerical approaches that are used to model the thermal fi elds and residual stress development. Details of the microstructural, mechanical properties and residual stress development in inertia friction-welded Ni-based superalloys, titanium alloys, steels and other alloys are also discussed.

 

اتصال با استفاده از تغییرشکل پلاستیک

Joining by plastic deformation

اتصال با استفاده از تغییرشکل پلاستیک

ABSTRACT

Vehicles such as aircraft and cars comprise a large number of mechanical parts produced by a variety of manufacturing processes. Cars generally consist of 10,000–30,000 parts, and the number of parts in aircraft is counted in millions. A trend in manufacturing such products is that both the number of parts and their complexity are increasing, including new combinations of dissimilar materials. Welding, adhesive bonding and mechanical fastening are typically used to join components during product assembly. In fusion welding, workpieces are joined by the application of an external heat source which melts material around the interface. Although the use of welding is widespread, the high temperatures required may reduce the quality, accuracy and reliability of joined parts. The strength of adhesively bonded and mechanically fastened joints is almost always lower than that achieved by welding. Commercial requirements for higher performance, higher productivity and lower cost in joining operations are becoming more demanding. In addition, strong joining of dissimilar materials is increasingly required. For example, high strength steel and aluminium sheets must be joined in some current car models, to allow weight reduction. There is therefore a need to identify new joining methods for new applications and materials.

 

سیلان مواد در طول جوشکاری اصطکاکی اغتشاشی Ti-6Al-V

Material Flow During Friction Stir Welding of Ti-6Al-4V

سیلان مواد در طول جوشکاری اصطکاکی اغتشاشی Ti-6Al-V

ABSTRACT

6 mm thick Ti-6Al-4V butt joints were produced with a tracer material embedded in the joint under a variety of process conditions, namely rotational speed and traversing speed, in an attempt to relate the welding process parameters to the material flow behavior via post weld radiographic and metallographic evaluations. It was found that by embedding refractory alloy powder into the joint line, welding through it, and subsequently x-raying the joint, the material flow patterns could be examined. The tracer material was distributed over a wider area in the weld zone relative to its starting position, implying a fair amount of mixing occurred even though little vertical movement of the tracer material was observed. There was minimal effect of material flow patterns as a function of welding parameters observed using the tracer material and radiographic examination, but defect formation in the root, where there was no tracer material, examined by cross sectional metallographic evaluations were found to be dependent on the rotational speed and traversing speed conditions. Lack of penetration defects were generally associated with relatively “cold” welding conditions (low rotational speed/high traversing speeds) and voids with “hot” conditions (high rotational speed/low traversing speeds).

 

اثر عملیات حرارتی در جوشکاری انفجاری فولاد زنگ نزن/مس

Effect of heat treatment on bonding interface in explosive welded
copper/stainless steel

اثر عملیات حرارتی روی فصل مشترک اتصال در جوشکاری انفجاری فولاد زنگ نزن/مس

ABSTRACT

In this investigation, explosive welding and heat treatment processes provided an effective method for manufacturing high-strength and high-ductility copper/ austenitic stainless steel couple. In order to improve diffusion in the interface of copper/stainless steel, first the tensile samples were provided from the welded part, then they were subjected to annealing at 300 C (below recrystallization temperature) for 8–32 h with 8 h intervals and then samples were cooled in the furnace. Optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were utilized to evaluate the possibility of diffusion in the joints. Moreover, in order to measure the hardness of the samples, microhardness test was performed. Microstructural evaluations showed that the stainless steel 304L had a wavy interface. Furthermore, the post heat treatment process resulted in great enhancement of diffusion. Microhardness measurements showed that the hardness of the sample near to the interface is greatly higher than other parts; this is due to plastic deformation and work hardening of copper and stainless steel 304L in these regions. The interface of samples with and without the post heat treatment was exhibited ductile and brittle fracture, respectively.

 

جوشکاری حالت جامد آلیاژ برنج Cu-Zn و فولاد

Solid-state bonding of alloy-designed Cu–Zn brass and steel

associated with phase transformation by spark plasma sintering

جوشکاری حالت جامد آلیاژ برنج Cu-Zn مخصوص و فولاد وابسته به استحاله فازی

به وسیله ی زینترینگ به کمک قوس پلاسما

ABSTRACT

Solid-state bonding between steel and a Cu alloy was studied to investigate fabrication of advanced bimetallic composites by using spark plasma sintering (SPS). In order to obtain proper bonding strength between the mating materials, Si and Al were alloyed to Cu–Zn brass to enhance interdiffusion with steel. The alloying elements diffused from the Cu alloy to steel, which transformed from the gamma to alpha phase during bonding. Owing to the phase stability of steel, the new columnar microstructure that evolved during the transformation across the joint interface showed high bonding strength between the mating alloys. The samples bonded without fracture, defects, or inhomogeneous deformation. Microstructural observations, elementary mapping, and mechanical testing demonstrated that the SPS technique and specific bonding parameters enhanced the interdiffusion between the metals. This novel method would be well suited to strengthen bonding between two dissimilar metals with different diffusion coefficients.

 

ارزیابی ساختار در اتصال نفوذی آلیاژ تیتانیوم/فولاد زنگ نزن

THE EVOLUTION CHARACTERISTICS AND NUMERICAL
ANALYSIS OF DIFFUSION BONDING INTERFACE
STRUCTURE OF TITANIUM ALLOY/Cu/STAINLESS STEEL

ارزیابی خصوصیات و آنالیز عددی ساختار در فصل مشترک اتصال نفوذی آلیاژ تیتانیوم/فولاد زنگ نزن

ABSTRACT

Carries on the investigation to the titanium alloy/Cu/stainless steel intermetallic compound of bonding interface in the meantime, to make a thermodynamic model of the interface element diffusion to have a numerical simulation of the diffusion distance and diffusion temperature, time. Using analysis methods of stretching test, microhardness test, SEM and EDS, to investigate and research the mechanical properties, the interface structure characteristic, the principal element atomic diffusion mechanism of joints thermal simulation and the vacuum diffusion bonding of Ti-6Al-4V/Cu/304, the reacting phases are produced and the distribution range . The results show that when bonding prssere is 5.0 MPa ، the joints tensile strength first increase and then decreases, with bonding temperature and time rising, When bonding temperature is 1223K, bonding time is 3.6 ks, there is a maximum tensile strength that is 162.73 MPa. However, it will is disadvantageous to performance of the joints, when bonding temperature and time extended overly. It formed multi-phase transition organizations by solid solution, intermetallic compounds in the bonding interface, such as Ti2Cu, TixCuy , Ti2Fe, TiFe2 and TiFe. Effect of TixFey on strength of the joints is slightly inferior the TixCuy compound. The fracture is mainly by the titanium alloy side region III for the source dehiscence, developing in the weak diffusion layer.

 

ساختار اتصالات جوشکاری شده فولادهای هاردوکس

Structure and hardness changes in welded joints of Hardox steels

ساختار و تغییرات سختی در اتصالات جوشکاری شده فولادهای هاردوکس (Hardox)

ABSTRACT

In the article, the structure and change in hardness of the welded Hardox 400 and Hardox 500 steels have been presented. It has been shown that structures of lower wear resistance are being created as a result of welding those materials in the “as delivered” state (i.e. with the tempered martensite structure) within the heat-affected zones. They are as much as up to 90 mm wide, and that causes their non-uniform and fast wear in the anticipated applications. Based on microscopic tests and hardness measurements a method of thermal joints treatment has been proposed, consisting in their hardening and low-temperature tempering (self-tempering) at the heat-affected zones. It leads to reproduction of that area structure, similar to the native material structure. In the laboratory conditions, a heat treatment differing from the usual practice (stress-relief annealing or normalizing) has not led to welding incompatibilities (cracks).