SOW_Amended.pdf

GOVERNMENT REQUIREMENTS

BACKGROUND

The Inorganic Chemical Metrology Group of the Chemical Sciences Division within the National

Institute of Standards and Technology (NIST) is responsible for the development of hundreds of

NIST Standard Reference Materials (SRMs) and development of new and improved methods of testing for a wide range of materials. To accomplish these tasks, the group procures materials and characterizes them for the constituents that will be certified as well as related physical and chemical characteristics that determine stability, viz. shelf life, and fitness for purpose.

Hydrogen contents of alloys must be controlled because hydrogen can cause embrittlement, increasing the likelihood of failure of a machine part manufactured with the alloy. Because titanium alloys are used in key components of airplane bodies and wings, and other transportation, aerospace, and power generation equipment, the impact of failure may be catastrophic. Therefore, tight specifications have been placed on hydrogen content, and manufacturers routinely test their products against those specifications. Quality assurance procedures include the use of certified reference materials to ensure that test results are accurate and reliable. NIST scientists developed

SRMs 2452, 2453, and 2454 to fill this need. The SRMs contain stable amounts of hydrogen.

Stability of hydrogen content is critical because hydrogen easily diffuses to and from the atmosphere, changing the concentration in the metal. SRMs that change with time are useless for long term quality assurance of test method performance.

NIST developed a preferred process for dosing titanium with known quantities of hydrogen described in a paper by R. Paul and R. Lindstrom (Metallurgical and Materials Transactions A –

Physical Metallurgy and Materials Science, Vol. 43A, Issue 12, pp 4888-4895 (2012)). The titanium is taken to high temperature in a vacuum enclosure to remove all native hydrogen, followed by dosing with a known quantity of hydrogen introduced into the system. The dosed titanium is then taken through a heat treatment process to convert all hydrogen to chemically bound forms that are stable and will not allow the hydrogen to diffuse out of the metal. The NIST process shows by residual gas analysis whether all hydrogen is converted to chemically bound forms.

It is known that most common titanium alloys behave similarly when subjected to typical test methods for hydrogen content. Common sense dictates that the alloy be a commonly produced alloy for the sake of similarity to a high proportion of the materials tested by manufacturers and their clients. Suggested candidates are 6Al-4V (used for the NIST SRMs) and commercial purity titanium, the two most common materials tested by the industry.

NIST is developing a renewal SRM to replace SRM 2454 Hydrogen in Titanium. The replacement requires specially prepared titanium of commercial purity or of a produced alloy to be physically and chemically treated to create a stable material containing a known amount of hydrogen. The material is needed in a final form that can be bottled for certification testing by NIST. It is intended that the known quantity of hydrogen be used in the value assignment of the renewal SRM to be numbered SRM 2454a. The unit size will be the same as for SRM 2454, i.e. 10 g per bottle. NIST is seeking a material that requires no additional preparation for these activities and uses. A material of this description and performance was prepared and successfully certified as SRM 2453a. The same process and resulting material is needed for SRM 2454a.

PURPOSE

The Contractor shall develop and deliver 7.5 kg of specially prepared titanium in pin form containing hydrogen at a target mass fraction of 215 mg/kg with the final product containing between 210 mg/kg and 220 mg/kg total hydrogen (mean for tested representative samples).

The required deliverables are a specially prepared batch of titanium or titanium alloy with specified hydrogen composition, specified physical dimensions, and specified stability, along with a report providing test results and information on the preparation of the titanium.

The processing required to create the material is a set of specialized activities requiring capabilities for vacuum heat treatment, gas handling, machine tool operation, and chemical testing. NIST intends to use the resulting batch of titanium to develop an SRM by bottling the titanium and testing it for amount and homogeneity of hydrogen.

SCOPE OF WORK

The Contractor shall manufacture and deliver 7.5 kg of specially processed titanium containing a mean mass fraction of between 210 mg/kg and 220 mg/kg total hydrogen all in chemically bound forms. The contractor shall perform specified testing and prepare a report to accompany the titanium. Specific tasks are enumerated below.

NIST requires that the hydrogen dosing process be a process based on parameters and procedures found in the published work of R. Paul and R. Lindstrom (Metallurgical and Materials

Transactions A – Physical Metallurgy and Materials Science, Vol. 43A, Issue 12, pp 4888-4895

(2012)) by which the titanium is taken to high temperature in a vacuum enclosure to remove all native hydrogen, followed by dosing with a known quantity of hydrogen introduced into the system. The process shall incorporate a heat treatment that converts all hydrogen to chemically bound forms that are stable and will not allow the hydrogen to diffuse into or out of the metal. In addition to chemical treatment of the titanium, the material must be prepared in pin form with pins being 2 mm to 3 mm diameter and 4 mm to 5 mm long.

The produced material shall be of the same form chemically and physically as SRM 2453a, because the two SRMs are integral parts of an industry system for validation of test methods and quality assurance of produced titanium alloys. Laboratories require multiple SRMs for the purpose of validation of linearity and accuracy of test method calibrations over a range of hydrogen mass fractions.

TASKS

The Contractor shall meet the following requirements by providing one batch of processed titanium, by performing the required tests, and by providing a report:

1. Production Size: The Contractor shall provide one (1) batch of either titanium or a titanium alloy having a total mass of 7.5 kg and containing a mean mass fraction of chemically bound hydrogen between 210 mg/kg and 220 mg/kg.

2. The Contractor shall demonstrate acceptable mean values and uniformity of dimensions and masses of individual pins by measuring the dimensions of 30 randomly selected pins from the batch. The mean pin mass must be in the range of 0.09 g to 0.11 g, and the standard deviation of the 30 measurements of mass must be less than or equal to 0.02 g.

Pin dimensions must be 2 mm to 3 mm diameter and 4 mm to 5 mm long.

3. The Contractor shall demonstrate acceptable mean value and homogeneity of total hydrogen content by testing 30 individual pins selected at random from the batch. The mean value shall be in the range of 210 mg/kg to 220 mg/kg, and the homogeneity shall be such that the standard deviation of the test results is less than or equal to 10 mg/kg. Testing shall be performed using inert gas fusion with thermal conductivity detections and gas dosing calibration in compliance with ASTM International E1447 Standard Test Method for Determination of Hydrogen in Titanium and Titanium Alloys by Inert Gas Fusion Thermal Conductivity/Infrared Detection Method with gas dosing calibration. Test result shall be validated by accurate results obtained from analysis of one or more NIST SRMs.

4. The Contractor shall demonstrate stability of the total hydrogen in the material by repeating the hydrogen testing of task 3 on a second set of 30 pins at least two (2) weeks after the first tests were completed. Mean values of hydrogen results from the two sets of results shall agree within 5 mg/kg.

5. The Contractor shall provide a written report of the hydrogen dosing value as mass fraction of hydrogen (H) added to the titanium and the results of testing performed for items 2, 3, and 4 above with all individual test results and brief descriptions of test methods.

6. The Contractor shall ship the material in a single container to NIST in Gaithersburg, Maryland. The container must provide protection for the material from contamination by moisture and foreign substances.

PERIOD OF PERFORMANCE

The period of performance shall be 180 days from award of this requirement.

PLACE OF PERFORMANCE

All work shall be accomplished at the Contractor’s facility.

DELIVERABLES

Description Quantity Due Date

Batch of titanium pins processed and tested as required.

7.5 kg No later than one hundred eighty (180) days after award of contract.

Written report containing all test results for homogeneity assessment, quantitative analyses, and stability analyses.

One No later than one hundred eighty (180) days after award of contract

GOVERNMENT ACCEPTANCE

The Government technical point of contact will inspect and confirm that all minimum requirements in this statement of requirements have been met.

PERFORMANCE REQUIREMENT SUMMARY

Desired Output

Specifications Monitoring Method

One batch of processed titanium that meets the specifications set forth in section III of this

SOW

See scope of work and preparation method sections.

Contractor must perform testing and provide a report.

Accuracy of test method must be demonstrated by the contractor using one or more

NIST SRMs. Report summarizing analytical and quality control results

Report documents compliant with specifications in the tasks section of this SOW.

CONTRACTOR’S MINIMUM QUALIFICATIONS

Prior to the award of the contract, the contractor must have in operation a system for processing titanium to contain hydrogen in chemically bound forms only, because the NIST project timeline will not allow for building new capability. The contractor must have expertise in the analytical determination of total hydrogen in titanium using ASTM International E1447 Standard Test

Method for Determination of Hydrogen in Titanium and Titanium Alloys by Inert Gas Fusion

Thermal Conductivity/Infrared Detection Method with gas dosing calibration.