Hardness and Charpy tests on Titanium alloys. 1

[WendelTrento]

Dears,

Goodnight,

I received a Material specification (Titanium alloy - Ti-6Al-4V, UNS R56400).

I don't have good metallurgical knowledge in these alloys.

Could you explain to me why you placed the points below?

Mechanical Properties:
1 - Hardness is not a good indicator of the mechanical properties of titanium alloys.
2 - Tensile properties shall be determined using a strain rate of 0.003 to 0.007 in./in./min through the specified yield strength, and then increasing the rate so as to produce failure in approximately one additional minute.

Impact Properties
1 - Impact toughness behavior does not correlate well with ductility or fracture toughness for titanium alloys. If a specific fracture toughness is desired, fracture toughness testing according to ASTM E1820 should be performed.

I will be very grateful for the support.

Att,

Wendel Trento

 

[weldstan]

Brinell hardness values which reflect tensile strength of ferritic (BCC) carbon and alloy steel, do not correlate the same to titanium alloys and other non BCC crystaline metals.

 

[EdStainless]

How well do you understand the HT and microstructure of 6-4?
The issue with Ti is that you need to know both the structure and HT condition.
And then you can look at hardness.
Fracture toughness does not correlate with ductility in any broad sense.
Again if you have two samples of the same alloy with only slightly modified HT then it might show you something.

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P.E. Metallurgy, consulting work welcomed