YY 0117.2-2024Implants for surgery - Forgings and castings for bone joint prostheses - Part 2: ZTi6Al4V titanium alloy castings (English PDF)

4.1 Raw materials

4.1.1

The raw materials for manufacturing castings for bone joint prostheses shall be ingots or forged bars. Ingots shall undergo two or more melting processes under vacuum or inert gas protection. Forged bars are bars formed by forging the aforementioned ingots and removing the oxide scale.

4.1.2

Castings and specimens can be cast from the same master furnace alloy, or from the same batch of alloys from a particular master furnace alloy.

4.2 Chemical composition

The tests shall be conducted according to the method described in 5.1.The chemical composition of the castings shall conform to the specifications in Table 1.

Other elements generally include. Sn, Mo, Cr, Mn, Zr, Ni, Cu, Si, and Y (alloying elements contained in this designation shall be deleted). Under normal circumstances, these do not need to be tested. Random checks may be conducted if deemed necessary by the purchaser. The results of random checks shall conform to the specifications in

Table 1.

Table 1 -- Chemical composition of castings

4.3 Mechanical properties

4.3.1

Conduct the tests according to the method described in 5.2.The mechanical properties of the castings shall conform to the specifications in Table 2.

Table 2 -- Mechanical properties of castings 4.3.2 When the purchaser has other mechanical property requirements for the castings, the inspection items, indicators and inspection methods shall be negotiated by both the supplier and the purchaser and specified in the part drawings and special technical documents.

4.4 Surface quality

4.4.1 Surface contamination

The test shall be conducted according to the method described in 5.3.1.The surface of the casting shall be free of the alpha layer. If necessary, it may be removed by methods such as sandblasting or acid pickling.

4.4.2 Appearance

4.4.2.1

Conduct the test according to the method described in 5.3.2.The casting shall be thoroughly cleaned. There shall be no burrs, flash, etc. The gating and riser on the unmachined surface shall be ground flush with the casting surface. The gating and riser on the machined surface is allowed to protrude 5 mm above the adjacent surface without affecting X-ray inspection.

4.4.2.2

Conduct the test according to the method described in 5.3.2.The machining and scribing reference areas of the casting shall be flat.

4.4.3 Surface roughness

The test shall be conducted according to the method described in 5.3.3.The surface roughness Ra value of the unmachined surface of the casting shall not exceed 12.5 µm.

4.4.4 Surface defects

4.4.4.1

Conduct the test according to the method described in 5.3.4.The casting shall be free from cracks, cold shuts, and penetrating defects.

4.4.4.2

Conduct the test according to the method described in 5.3.4.Permissible defects on the unmachined surfaces of the casting shall conform to the requirements of Table 3.

There shall be no defects on the corresponding surfaces. Defective holes shall be thoroughly cleaned and free of any contaminants. Defects on unmachined surfaces may be repaired by grinding and welding. The repair depth shall not exceed 1/3 of the thickness. Welding requirements for casting defects shall be in accordance with Annex

A. The surface shall be free of discontinuous defects after grinding and welding.

Table 3 -- Permissible defects on the unmachined surfaces of castings (inspection area. 25 mm × 25 mm) 4.4.4.3 Conduct the test according to the method described in 5.3.4.On the surface to be machined, defects other than cracks and cold shuts are permitted, not exceeding the machining allowance.

4.5 Internal quality

The test shall be conducted according to the method described in 5.4.The permissible level of internal defects in the casting shall be evaluated with reference to the pictures in HB 6573 and shall comply with the provisions of Table 4; or the supplier and the purchaser shall agree on the acceptable limits recommended in Annex A of YY/T 1565-

2017.

Table 4 -- Maximum permissible level of internal defects in castings

4.6 Appearance and dimensions

The geometry and dimensions of the casting shall conform to the specifications in the casting drawing. General dimensional tolerances shall be tested according to the method described in 5.5 and shall conform to grades CT6~CT7 specified in HB 6103.

Special dimensional tolerances may be specified on the casting drawing through negotiation between the supplier and the purchaser.

4.7 Casting supply state

Castings shall be supplied in an annealed or hot isostatic pressing condition.

NOTE. Annealing shall be performed at 700°C~800°C for 1 h, followed by air cooling. Hot isostatic pressing shall be carried out according to the specific technical documents.

5.1 Chemical composition

Chemical composition is tested according to GB/T 4698 (all parts) or other recognized analytical methods (existing ISO methods or methods recommended by national or industry standards).

5.2 Mechanical properties

The tensile test shall be performed in accordance with the provisions of GB/T 228.1.

5.3 Surface quality

5.3.1 Surface contamination

Perform the test according to GB/T 23603.Inspect at 100x magnification.

5.3.2 Appearance

Inspect with normal or corrected vision. If necessary, use general measuring tools or special gauges to check the height of the gating system and riser.

5.3.3 Surface roughness

The test shall be conducted using the sample comparison method or according to the method given in GB/T 10610.

5.3.4 Surface defects

Surface discontinuities shall be inspected according to the fluorescence penetrant testing method specified in YY/T 0343.Other defects shall be inspected with normal or corrected visual acuity. If necessary, a magnifying glass of no more than 10x may be used for inspection. The dimensions of pore-like defects shall be inspected using general measuring tools or special inspection tools.

5.4 Internal quality

Internal quality inspection of castings shall refer to the images in HB 6573.It shall be carried out according to the provisions of HB 20160 or YY/T 1565-2017.

5.5 Casting shape and dimensions

The external shape shall be in accordance with the casting drawing or casting process specification. Dimensions shall be measured using general measuring tools or special

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