Evolution of microstructure and texture in the stir zone of commercially pure titanium during friction stir processing

Author(s):  
Abhishek Kumar Singh ◽  
Lalit Kaushik ◽  
Jaiveer Singh ◽  
Hrishikesh Das ◽  
Mounarik Mondal ◽  
...  
Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 799 ◽  
Author(s):  
Alihan Amirov ◽  
Alexander Eliseev ◽  
Evgeny Kolubaev ◽  
Andrey Filippov ◽  
Valery Rubtsov

The use of electric arc or gas welding in the manufacture of titanium components often results in low quality welded joints due to large residual stresses and strains. A successful solution to this problem can be found in the application of friction stir welding. However, friction stir welding (FSW) of titanium alloys is complicated by rapid tool wear under high loads and temperatures achieved in the process. This paper studies the durability of a tool made of ZhS6U Ni-based superalloy used for friction stir processing of commercially pure titanium and the effect of the tool wear on the weld quality. The total length of the titanium weld formed by the tool without failure comprised 2755 mm. The highest wear of the tool is observed at the base of the pin, which brings about the formation of macrodefects in the processed material. The tool overheating causes an increase in the dendrite element size of ZhS6U alloy. The transfer layer contains chemical elements of this alloy, indicating that the tool wear occurs by diffusion and adhesion. As a result of processing, the tensile strength of commercially pure titanium increased by 25%.


2012 ◽  
Vol 05 ◽  
pp. 367-374 ◽  
Author(s):  
ALI SHAMSIPUR ◽  
SEYED FARSHID KASHANI-BOZORG ◽  
ABBAS ZAREIE-HANZAKI

In the present investigation, novel Ti / SiC surface nano-composite layer was successfully fabricated by dispersing nano-sized SiC particles into commercially pure titanium plates employing friction stir processing technique. The process parameters such as tool rotation and advancing speeds were adjusted to produce defect-free surface composite layer, however, uniform distribution of the nano-size SiC particles in a matrix of titanium was achieved after the second pass. The micro hardness value of the Ti / SiC nano-composite surface layer was found to be ~534 HV; this is 3.3 times higher than that of the commercially pure titanium substrate. No reaction was detected between SiC powders and the titanium matrix after friction stir processing.


Author(s):  
Aleksandra Fortier ◽  
Nilesh Kumar ◽  
Mageshwari Komarasamy ◽  
Rajiv S. Mishra

Manufacturing of a component through powder metallurgy (PM) route involves at least three critical steps: powder blending, compaction, and sintering. Overall, the PM route takes 4 to 8 steps to get to the final product. Moreover, it requires a huge amount of capital investment to perform every step of the manufacturing process via PM route. Friction stir processing (FSP) is a derivative of friction stir welding which has emerged as a generic microstructural modification tool in last one decade. The aim of the current work was to explore the possibility of decreasing the number of steps required in the manufacturing of a product using the PM technique. Using the FSP method, the manufacturing process is reduced to two steps and the mechanical properties of the final product are significantly improved. In this study, commercially pure titanium (Ti) powder was used. The two-step process appeared extremely efficient and it involved: 1) constraining the Ti-powder in a die and using a punch to consolidate it in a final disk-like geometry, 2) next, the consolidated disk-shaped product was processed using FSP tool and methods. Initial mechanical characterization results show peak hardness of the FSP processed Ti-powder product to be approximately 436 HV0.3 with average hardness measured at about 251 HV. The electron backscattered diffraction of the FSP-assisted sintered region showed equiaxed grains with average grain size to be 440 ±254 nm. The initial result indicates FSP can be used as a manufacturing tool for consolidating powders in to bulk solid form.


2010 ◽  
Vol 667-669 ◽  
pp. 1165-1170 ◽  
Author(s):  
Alexander V. Polyakov ◽  
Dmitriy Gunderov ◽  
Georgy I. Raab

This work reports on the results of investigation of microstructure change of commercially pure titanium Grade 4 with the increase of the number of ECAP-Conform passes. There has been investigated influence of continuous equal-channel angular pressing by the scheme “Conform” (ECAP-C) on the structure and properties of commercially pure titanium Grade 4. It has been demonstrated that as a result of first two ECAP-C cycles titanium structure is strongly fragmented and deformation bands are formed. With the further increase of ECAP-C passes to 6 the band structure is transformed into ultrafine-grained (UFG) structure with the grain size of about 250 nm. The strength of titanium regularly grows with the increase of the number of ECAP-C passes, while ductility, which settles after first cycle on the level of 12%, is almost not changed with the further strain degree increase. As a result of the subsequent drawing of titanium after ECAP-C its strength additionally increases to 1300 MPa, with retention of ductility about 11%.


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