Mechanical Strength and Microstructural Characterization of SUS304 Brazed Joints with BNi-2 Filler Metal: Influence of Brazing Temperature and Time

2007 ◽  
Vol 124-126 ◽  
pp. 1673-1676 ◽  
Author(s):  
Yong Won Lee ◽  
Jong Hoon Kim ◽  
Young Sik Song ◽  
Chang Sung Seok

The formation of intermetallic compounds in brazed joints between SUS304 and nickel-based filler metal is a major concern, since they considerably degrade the mechanical properties of joints. In this study, the SUS304, which is used widespread, as a general material was vacuum brazed with BNi-2 filler metal, and discussed to determine the influence of different brazing temperature and time on the strength of brazed joints. The results showed that, the mechanical properties of brazing layer could be stabilized through increasing the brazing temperature over 100° C more than melting temperature of filler metal, and increasing the brazing time over 120min. long, and diffusing enough the intermetallic compounds formed in the brazing layer to the base metal.

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Jinya Katsuyama ◽  
Tohru Tobita ◽  
Yutaka Nishiyama ◽  
Kunio Onizawa

In order to provide the technical basis for the judgment of the needs of surveillance specimens of heat-affected zone (HAZ) in reactor pressure vessel (RPV) steels, we performed a research on the characterization of metallurgical and mechanical properties of the HAZ in RPV steels. The distributions of grain size and phases were drawn as a map based on temperature histories around HAZ obtained from welding simulation. Referring to the HAZ map, typical HAZ materials were made by simulating temperature histories including postweld heat treatment (PWHT) within the HAZ. Metallurgical and mechanical characteristics for those HAZ materials were compared with those of base metal. From the results, it is clear that mechanical properties of HAZ materials depend not on the prior austenitic grain size but mostly on the phases. Concerning on the fracture toughness in HAZ, HAZ materials close to weld metal indicated higher toughness than that of base metal due to mixed structure of martensite and lower-bainite, while HAZ materials close to base metal were equivalent or slightly lower toughness than that of base metal due to the same phase as base metal of upper-bainite.


Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 875
Author(s):  
Hao Tian ◽  
Jianchao He ◽  
Jinbao Hou ◽  
Yanlong Lv

TiB crystal whiskers (TiBw) can be synthesized in situ in Ti alloy matrix through powder metallurgy for the preparation of a new type of ceramic fiber-reinforced Ti matrix composite (TMC) TiBw/Ti-6Al-4V. In the TiBw/Ti-6Al-4V TMC, the reinforced phase/matrix interface is clean and has superior comprehensive mechanical properties, but its machinability is degraded. Hence, the bonding of reliable materials is important. To further optimize the TiBw/Ti-6Al-4V brazing technology and determine the relationship between the microstructure and tensile property of the brazed joint, results demonstrate that the elements of brazing filler metal are under sufficient and uniform diffusion, the microstructure is the typical Widmanstätten structure, and fine granular compounds in β phase are observed. The average tensile strength of the brazing specimen is 998 MPa under room temperature, which is 97.3% of that of the base metal. During the high-temperature (400 °C) tensile process, a fracture occurred at the base metal of the highest tensile test specimen with strength reaching 689 MPa, and the tensile fracture involved a combination of intergranular and transgranular modes at both room temperature and 400 °C. The fracture surface has dimples, secondary cracks are generated by the fracture of TiB whiskers, and large holes form when whole TiB whiskers are removed. The proposed algorithm provides evidence for promoting the application of TiBw/Ti-6Al-4V TMCs in practical production.


Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 785 ◽  
Author(s):  
Lin Wang ◽  
Daqian Sun ◽  
Hongmei Li ◽  
Xiaoyan Gu ◽  
Chengjie Shen

Ti3Al-Nb alloy (Ti-24Al-15Nb) was welded by a pulsed laser welding system without and with pure Nb filler metal. The results indicated that pure Nb filler metal had profound effects on the microstructures and mechanical properties of the laser-welded joints. The joint without filler metal consisted of the weld zone (α’2 + B2), heat affected zone HAZ1 (α2 + B2), HAZ2 (α2 + O + B2) and base metal (α2 + O + B2), and gas pores were generated in the weld resulting in the deterioration of the joint strength (330 MPa) and elongation (1.9%). When the Nb filler metal was used, the weld microstructure (NbTi solid solution + O + B2) was obtained, and the joint properties were significantly improved, which was associated with the strengthening effect of the NbTi solid solution, O phase precipitation and the slip transmission between O and B2 phases, and the restraining of the formation of martensite (α’2) and gas pores in the weld. The strength (724 MPa) and elongation (5.1%) of the joint increased by 119.4% and 168.4% compared with those of the joint without filler metal, and the joint strength was able to reach 81.7% of the base metal strength (886 MPa). It is favorable to use pure Nb filler metal for improving the mechanical properties of laser-welded Ti3Al-Nb alloy joints.


2018 ◽  
Vol 910 ◽  
pp. 35-40
Author(s):  
Eswaran Elango ◽  
Somasundaram Saravanan ◽  
Krishnamorthy Raghukandan

This study focuses on effect of post weld heat treatment (PWHT) on interfacial and mechanical properties of Al 5052-SS 316 explosive clad with copper interlayer at varied loading ratios and inclination angles. The use of interlayer is proposed for the control of additional kinetic energy dissipation and to alleviate the formation of intermetallic compounds at the interface. The Al-Steel clads are subjected to PWHT at varied temperatures (300°C-450°C) for 30 minutes and the results are presented. The microstructural characterization of as-clad and PWHT samples is observed by an optical microscope and Scanning Electron Microscope (SEM). Maximum hardness is obtained at the interface of the as-clad and PWHT samples. Increase in PWHT temperature enhances the tensile strength of the composite, whereas, the tensile strength decreases at 300°C due to the diffusion of Al and Cu elements and the formation of detrimental intermetallic compounds.


Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 526
Author(s):  
Yuzhen Lei ◽  
Hong Bian ◽  
Wei Fu ◽  
Xiaoguo Song ◽  
Jicai Feng ◽  
...  

Titanium and zirconia (ZrO2) ceramics are widely used in biomedical fields. This study aims to achieve reliable brazed joints of titanium/ZrO2 using biocompatible Au filler for implantable medical products. The effects of brazing temperature and holding time on the interfacial microstructures and mechanical properties of titanium/Au/ZrO2 joints were fully investigated by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and X-ray diffraction (XRD). The results indicated that the typical interfacial microstructure of the titanium/Au/ZrO2 joint was titanium/Ti3Au layer/TiAu layer/TiAu2 layer/TiAu4 layer/TiO layer/ZrO2 ceramic. With an increasing brazing temperature or holding time, the thickness of the Ti3Au + TiAu + TiAu2 layer increased gradually. The growth of the TiO layer was observed, which promoted metallurgical bonding between the filler metal and ZrO2 ceramic. The optimal shear strength of ~35.0 MPa was obtained at 1150 °C for 10 min. SEM characterization revealed that cracks initiated and propagated along the interface of TiAu2 and TiAu4 reaction layers.


Sign in / Sign up

Export Citation Format

Share Document