title: Mechanical behaviour of Titanium, Ti-6Al-4V (wt %) alloy and Ti-47Al-2Cr (at %) alloy produced using powder compact forging

authors: Nadakuduru, Vijay Navaratna

subjects: mechanical behaviour

abstract: Powder compact forging was used to produce bulk consolidated titanium and Ti-6Al-4V (wt %) and Ti-47Al-2Cr (at%) alloy disks from hydrogenated and dehydrogenated (HDH) and gas atomised powders (GA) powders (in the case of titanium and Ti-6Al-4V) and a mechanically milled powder (in the case of Ti-47Al-2Cr alloy). The bulk titanium and Ti-6Al-4V (wt %) alloy have been produced by forging of the powder compacts. The Ti-47Al-2Cr (at %) alloy was produced using canned powder compact forging of a Ti/Al/Cr composite powder. The purpose of the present study is to investigate the deformation and fracture behaviour of the bulk consolidated as-forged materials, by conducting tensile testing at room temperature (RT) and examination of the fractured specimens which had near-α, α + β and γ phase structures, respectively. It was found that as-forged bulk titanium disk produced using HDH powder showed a yield point with a yield strength of ~700 MPa and with a considerable amount of ductility. While the as-forged Ti-6Al-4V (wt %) alloy produced using HDH powder, fractured prematurely without any yielding. On the other hand yielding was observed in the as-forged Ti-6Al-4V (wt %) alloy produced using GA powder, showing a yield strength of ~970 MPa and a considerable amount of plastic strain to fracture. The bulk consolidated Ti-47Al-2Cr (at %) alloy also fractured prematurely with fracture strength of ~125 MPa. The mechanical behaviour of the as-forged bulk materials was found to be dependent on several factors such as initial powders used, green density of the powder compact, forging parameters used during forging. It was expected that the entrapped gas in green compacts, absorbed oxygen, porosity and inter-particle bonding play an important role on the quality of the as-forged material, which in turn affected the mechanical behaviour of the bulk material.

text: Mechanical behaviour of Titanium, Ti-6Al-4V (wt %) alloy and Ti-47Al-2Cr (at %) alloy produced using powder compact forging Powder compact forging was used to produce bulk consolidated titanium and Ti-6Al-4V (wt %) and Ti-47Al-2Cr (at%) alloy disks from hydrogenated and dehydrogenated (HDH) and gas atomised powders (GA) powders (in the case of titanium and Ti-6Al-4V) and a mechanically milled powder (in the case of Ti-47Al-2Cr alloy). The bulk titanium and Ti-6Al-4V (wt %) alloy have been produced by forging of the powder compacts. The Ti-47Al-2Cr (at %) alloy was produced using canned powder compact forging of a Ti/Al/Cr composite powder. The purpose of the present study is to investigate the deformation and fracture behaviour of the bulk consolidated as-forged materials, by conducting tensile testing at room temperature (RT) and examination of the fractured specimens which had near-α, α + β and γ phase structures, respectively. It was found that as-forged bulk titanium disk produced using HDH powder showed a yield point with a yield strength of ~700 MPa and with a considerable amount of ductility. While the as-forged Ti-6Al-4V (wt %) alloy produced using HDH powder, fractured prematurely without any yielding. On the other hand yielding was observed in the as-forged Ti-6Al-4V (wt %) alloy produced using GA powder, showing a yield strength of ~970 MPa and a considerable amount of plastic strain to fracture. The bulk consolidated Ti-47Al-2Cr (at %) alloy also fractured prematurely with fracture strength of ~125 MPa. The mechanical behaviour of the as-forged bulk materials was found to be dependent on several factors such as initial powders used, green density of the powder compact, forging parameters used during forging. It was expected that the entrapped gas in green compacts, absorbed oxygen, porosity and inter-particle bonding play an important role on the quality of the as-forged material, which in turn affected the mechanical behaviour of the bulk material.

year: 2011

title: Notes on the belemnite content of the Heterian and Ohauan stages at Kawhia Harbour, New Zealand

authors: Challinor, A.B.

subjects: New Zealand

abstract: The belemnite content of the Heterian and Ohauan stages at Kawhia Harbour is described. Six major species or groups are differentiated, each of which ranges through several hundred feet of strata. Other minor elements are also present. Belemnopsis keari Stevens is shown to be present in only a restricted group of beds in the upper part of the Waikutakuta Siltstone, and Belemnopsis alfurica (Boehm) may be present in the upper Waikutakuta Siltstone. A system of informal belemnite zones is suggested. The belemnite succession is well defined throughout most of the Heterian stage, but poorly defined in the Ohauan, and further work is required in the upper and lower parts of this stage.

text: Notes on the belemnite content of the Heterian and Ohauan stages at Kawhia Harbour, New Zealand The belemnite content of the Heterian and Ohauan stages at Kawhia Harbour is described. Six major species or groups are differentiated, each of which ranges through several hundred feet of strata. Other minor elements are also present. Belemnopsis keari Stevens is shown to be present in only a restricted group of beds in the upper part of the Waikutakuta Siltstone, and Belemnopsis alfurica (Boehm) may be present in the upper Waikutakuta Siltstone. A system of informal belemnite zones is suggested. The belemnite succession is well defined throughout most of the Heterian stage, but poorly defined in the Ohauan, and further work is required in the upper and lower parts of this stage.

year: 1968

title: Te Ahurei a Rangatahi sexual health programme: An evaluation

authors: Nikora, Linda Waimarie

subjects: youth

abstract: The Maori and Psychology Research Unit was engaged in August 2001 to evaluate a
sexual health programme delivered by Te Ahurei a Rangatahi. Established in 1997,
Te Ahurei a Rangatahi is a community based charitable trust that delivers a variety of
programmes to Rangatahi.

text: Te Ahurei a Rangatahi sexual health programme: An evaluation The Maori and Psychology Research Unit was engaged in August 2001 to evaluate a
sexual health programme delivered by Te Ahurei a Rangatahi. Established in 1997,
Te Ahurei a Rangatahi is a community based charitable trust that delivers a variety of
programmes to Rangatahi.

year: 2001-12-01