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By Trunnano | 18 April 2022 | 0 Comments

Causes of Black Bar Defects in TC4 Titanium Rod Rolling Process

Introduction to Ti6Al4V Powder TC4 Powder
TC4 titanium alloy material, also known as Ti-6Al-4V titanium alloy, is a kind of lightweight rustless metal with high strength. It is generally called "64 titanium" in Japan and "JIS type 60" in JIS. It belongs to the (α+β) type titanium alloy, having the advantages of both α and β titanium alloys, that is, good plasticity, good thermal strength (can be 400 in the long-term work), strong seawater corrosion resistance, simple production process, and it can be welded, cold and hot molding, and can be strengthened by quenching and aging treatment. It is mainly used in aircraft compressor discs and blades, ship pressure shells, large size forgings, die forgings, and so on. 

Physicochemical Properties of Ti6Al4V Powder TC4 Powder
TC4 titanium alloy has a series of advantages such as excellent corrosion resistance, low density, high specific strength, good toughness, weldability, etc., which have been successfully applied in aerospace, petrochemical, shipbuilding, automobile, and pharmaceutical sectors. In the process of hot forming, the surface of TC4 titanium alloy will form a layer of oxide, the hot forming temperature is different, and the color of oxide is not the same. When the hot forming temperature is about 600, the oxide scale is blue. When the hot forming temperature is about 850, the oxide scale is gray and reddish. When the forming temperature is 900, the oxide scale is gray. With the increase in temperature, the removal of the oxide scale becomes more and more difficult. The removal of titanium alloy oxide skin mostly adopts a two-step method, that is, first molten alkaline washing, and then pickling; However, the temperature of molten alkaline washing medium is high, which can reach about 450, and it is easy to cause premature aging strengthening of α+β and β titanium alloy semi-finished products, which brings difficulties to further processing. In addition, hot alkaline cleaning followed by nitric acid and hydrofluoric acid cleaning may lead to hydrogen embrittlement of titanium alloy surfaces.
Ti6Al4V Powder TC4 Powder Properties
Other Names Ti6Al4V Powder, TC4 Powder
Compound Formula TA0,TA1,TC4,TC4 ELI,TC11,TC17,TC18,TC21,TA7,TA12,TA15,TA17,TA19,
Molecular Weight N/A
Appearance grey powder
Melting Point N/A
Boiling Point N/A
Density N/A
Solubility in H2O N/A
Exact Mass N/A

Causes of Black Bar Defects in TC4 Titanium Rod Rolling Process: 
TC4 (Ti-6Al-4V) is a kind of Martensite A/3 two-phase titanium alloy with good comprehensive performance, and the working temperature can reach 450. It is widely used in important structural parts of the aviation industry, such as wing blades, aero-engine discs, etc. The phase titanium alloy TC4 titanium rods in two, if the micro area composition is uneven, bound to lead to abnormal macrostructure and microstructure, resulting in the abnormal area and normal area there were significant differences in hardness, make the material as a whole show uneven performance, eventually lead to fatigue crack source, brings great hidden danger to the safety of the parts, reduce the service life of the alloy.  In order to accurately judge the defect type, the metallographic structure was observed by a metallographic microscope to determine the abnormal area of the metallographic structure. The chemical composition segregation defect of mo - rich and Al - poor in the black fringe region was analyzed by sem. The composition segregation in the black stripe region was confirmed to be non-brittle segregation by the microhardness test. 
The experimental results show that the composition segregation and its types of TC4 titanium alloy can be determined effectively by the above method. Determine that this type of defect does not affect the use and can be delivered after removal. Such defects can be reduced or eliminated by controlling the selection of raw materials for titanium alloy ingots, material mixing, electrode preparation, and voltage and current during melting. The segregation of titanium alloy can be divided into hard segregation (hardness higher than normal zone, also known as brittle segregation) and soft segregation (hardness lower than normal zone, also known as non-brittle segregation) according to the hardness of the segregation part and the normal zone. If only non-brittle segregation is present in the product and all performance meets the requirements of the product standard, the product can still be delivered after segregation is eliminated.  Brittle segregation is not allowed to be delivered after removal and should be discarded in batches. 
A. For the black stripe defect of TC4 titanium rod found visually, the metallographic microscope was used to observe the tissue, and the difference between the defect area and the normal area was not significant, so the type of defect could not be determined; In addition, the chemical composition of defect area of titanium rod was analyzed by scanning electron microscope. It was found that the defect area was rich in heavy and aluminum-poor chemical element segregation. Finally, the segregation type of TC4 titanium rod was determined to be aluminum-rich and aluminum-poor non-brittle segregation. The composition segregation and its type of TC4 titanium alloy can be determined effectively by observing the microstructure, analyzing the composition of the micro-zone, and testing the microhardness. 
B. C4 titanium alloy bar segregation is rich in heavy aluminum poor non-brittle segregation, does not affect the use, can be continuously transported after cutting; This defect can be reduced or eliminated by controlling raw material selection, mixing, and electrode preparation parameters, as well as voltage and current during the smelting process. 

Main Supplier of Ti6Al4V Powder TC4 Powder
Luoyang Tongrun Nano Technology Co. Ltd. (TRUNNANO) is a trusted global chemical material supplier & manufacturer with over 12-year-experience in providing super high-quality chemicals and Nanomaterials, including silicon powder, nitride powder, graphite powder, zinc sulfide, calcium nitride, 3D printing powder, etc.
If you are looking for high-quality Ti6Al4V Powder TC4 Powder, please feel free to contact us and send an inquiry. ([email protected])


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