16-00814_-_Attachment_A_-_Statement_of_Work.pdf

Request For Proposal No. NB647020-16-00814 Charpy Specimens Page 1 of 6

ATTACHMENT A - STATEMENT OF WORK

Machining and Heat Treating of Charpy Impact Specimens

A. Background: The NIST Standard Reference Materials Program provides SRM 2092, SRM 2093, and SRM 2113

(Low-Energy Charpy Specimens), SRM 2096, SRM 2097, and SRM 2112 (High-Energy Charpy Specimens), and SRM 2098 (Super-High-Energy Charpy Specimens) (SRMs) to industry for the purpose of verifying Charpy impact testing machines. NIST Charpy SRMs are specified in the various industrial standards to verify the performance of industrial impact machines to assure a common measurement base for purposes of trade and commerce. All measurements made by United States industry under the American Society for Testing and Materials (ASTM) E23 test standard are traceable to NIST through these SRMs. These Charpy V-notch specimens are the highest demand SRMs, based upon number of units sold, that NIST distributes.

To produce verification specimens, production lots are heat treated in a batch. The whole heat treatment batch, which is typically 1200 or more specimens, is designated as the production lot made from a single corresponding lot of steel. No other material shall be mixed with the lot during processing. From this production lot, a pilot lot is selected for machining and acceptance testing as discussed herein.

B. Specimen Dimensions and Specifications: The Contractor shall manufacture Charpy V-notch specimens from NIST- supplied steel. For SRMs 2092/2093/2113 (low-energy specimens) and SRMs 2096/2097/2112 (high-energy specimens), NIST will supply the Contractor with AISI-SAE 4340 steel bars. For SRM 2098 (super-high-energy specimens), NIST will supply the Contractor with a maraging steel or another suitable steel. All specimens shall be machined to the following dimensions and specifications (see Figure 1):

(1) The material shall be cut and ground to the finished length of 55 mm 00.0 30.0

− (2.165 in. 00.0

012.0 − in.).

(2) One end of each specimen shall be stamped or etched with a lot code and a serial number; the other end shall be stamped or etched with the letters “NIST”. See Section (g) Marking Deliverables for the specifics.

(3) The Contractor shall determine the exact heat treatment needed to produce the required energy level.

(4) The specimen cross section dimensions shall be 10 mm ± 0.03 mm (0.394 in. ± 0.001 in.) ground square;

any two adjacent sides shall be square to 90° ± 9’.

(5) The surface roughness (Ra) shall be 1.6 micrometers (47 micro inches) or less on the notched surface and opposite surface and 3.2 micrometers (100 micro inches) or less on the other two longitudinal surfaces, plus both ends.

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(6) Notch Specifications:

(a) Centering of the notch shall be at 27.5 mm ± 0.20 mm (l.083 in. ± 0.008 in) from either end.

(b) The notch depth shall be 2.0 mm ± 0.025 mm (0.079 in. ± 0.001 in.), so that the material thickness below the base of the notch is 8.0 mm ± 0.025 mm (0.315 in. ± 0.001 in.).

(c) The notch shall be perpendicular to the longitudinal axis of the specimen to 90 degrees plus or minus 9 minutes.

(d) The included notch angle shall be 45° ± 1°, with a notch radius of 0.25 mm ± 0.025 mm (0.010 in. ±

0.001 in.).

(e) Specimen notches shall be ground on a surface grinder or cut with an electrical discharge machining process (EDM). Machining with a fly cutter, multi-tooth cutter or broach is not acceptable. To avoid burning or cold working the material at the base of the notch, the next to last grinding pass shall be more than 0.25 mm (0.010 in.) and less than 0.38 mm (0.015 in.). Appropriate machining oil shall be used during all grinding or machining, and notches shall be deburred. For EDM, the damage layer shall be less than 5 micrometers in depth.

Figure 1: Specimen Dimensions and Specifications (millimeters).

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C. Acceptance Testing Procedures:

(1) For SRMs 2092/2093/2113 (Low-Energy Specimens), and SRMs 2096/2097/2112 (High- Energy Specimens, the microstructure shall be 100 % tempered martensite. No ferritic, austenitic or bainitic structures shall be visible when polished sections are examined at 1000X.

(2) For all specimens, dimensions (length, thickness, width, notch configuration, etc.) shall be within the stated tolerances.

(3) The hardness of each specimen shall be within ± 1 HRC of the average of the pilot lot. This applies to low, high, and super-high energy level pilot lots.

(4) The average hardness of low energy specimens shall not be less than HRC 44.

(5) The acceptable ranges for the average energies of pilot lots are as follows:

(a) Low-energy specimens shall produce an average energy between 14.0 J and 20.0 J (10.0 ft.-lbf to 15.0 ft.-lbf).

(b) High-energy specimens shall produce an average energy between 88.0 J and 136.0 J (65.0 ft.-lbf to 100.0 ft.-lbf).

(c) Super-high-energy specimens shall produce an average energy between 176.0 J and

244.0 J (130.0 ft.-lbf to 180.0 ft.-lbf).

(6) Specimens at all energy levels shall meet the requirements below:

(a) The sample size (n) is calculated as follows:

E S n p

Where E is equal to 1.4 J or 5 % of the average energy for the 3 machines (whichever is the greater), and Sp is the pooled standard deviation of the 3 reference machines. The standard deviation (s), and pooled standard deviation (Sp), are calculated as follows:

1 sss pS ++ n xxxxxxs n i where sl, s2, and s3 are the standard deviations of the machines.

If the variance of the reference specimens is acceptable (k is less than 1.25), the sample size shall not exceed five.

(b) The number of outliers shall not exceed 5 % of the number of specimens impact tested in the pilot lot (4 is the maximum for a pilot lot of 75). The outlier analysis is performed using box-and whiskers plots to provide a graphical summary of the data and identify outliers. Outliers are defined as values that are lower than the first quartile or higher than the third quartile by more than 1.5 times the absolute difference between the first and third quartiles. (An outlier is not removed from analysis unless it shows physical evidence of jamming, material flaws, or other reason for atypical behavior.)

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D. Marking Deliverables

(1) The contract number shall be placed on or adjacent to all exterior mailing or shipping labels of deliverable items called for by the contract.

(2) Mark shipping containers as follows: the Contractor name and lot number shall be placed on or adjacent to all exterior mailing or shipping labels of pilot lot specimen shipments.

(3) All specimens shall be marked as follows:

(a) Individual specimens shall be stamped or etched on one end with one of the following lot numbers:

Low Energy: LL NNN

High Energy: HH NNN

Super-High Energy: SH NNN where "NNN" is the lot number as defined in (d)(2). These numbers will be assigned by the Charpy Coordinator.

(b) The serial number shall be stamped or etched below the lot number. Serial numbers shall begin with the number 1 and end with the last number produced with the lot. ·

(c) The opposite end shall be stamped or etched with the letters: “NIST”.

E. Pilot Specimen Testing and Approval: Pilot lot specimens shall be drawn from predetermined and agreed upon locations in the heat treatment baskets to assure consistency (exceptions may be made for continuous heat treatment processing). See (c) above for acceptance testing procedures. If the pilot specimens fail to meet the specifications in this contract, the Charpy Coordinator may suggest re-heat treatment of the batch, or may require starting with new material based on the test outcome. If new material is required, it will be provided to the Contractor by the Charpy Coordinator. The Charpy Coordinator will determine whether failed specimens are to be destroyed or returned to NIST at the Contractor's expense.

Sampling plan for NIST pilot lots

(1) Each pilot lot shall consist of 100 specimens.

(2) Provide specimens from each of the basket locations approved by the Charpy Coordinator

(3) If more than one basket is used, provide an equal amount of specimens from each basket and identify the relative position of the basket (top, middle, bottom, etc.).

(4) Provide a list of the serial numbers of specimens taken from each location from each basket.

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F. Production Specimen Testing and Approval: Production lot specimens shall be drawn at random when the lot is delivered to NIST. If the production lot specimens fail to meet the machining or marking specifications in this contract, the Charpy Coordinator may reject part or all of the lot. The Charpy Coordinator will determine the disposition of the failed specimens.

Sampling plan for NIST production lots

a. Random specimens, typically 100, are selected when the lot is delivered to NIST.

b. From the 100 random specimens, 75 are selected for measurement to verify dimensions and to determine a certified reference value for the lot.

c. From the 100 random specimens, the remaining 25 specimens are kept for future stability testing.

G. Unit Prices:

(1) Contract line item numbers (CLINs) 0001, 1001, 2001, 3001 and 4001 include a listing of the three (3) categories of CHARPY V-NOTCH STANDARD REFERENCE MATERIAL (SRM) specimens to be machined from steel supplied by the National Institute of Standards and Technology (NIST) in accordance with the requirements contained in this contract.

(2) Each delivery order issued under this contract will state the type and quantity of SRM(s) to be machined. Pricing will be in accordance with the Schedule of Machining Prices.

H. General Order Information: The Contractor shall provide machining of Charpy V-notch specimens under this contract only as directed on written delivery orders issued by the Contracting Officer in accordance with FAR 52.216-18 Ordering. The issuances of delivery orders by facsimile or by electronic commerce methods are hereby authorized.

I. Government Furnished Material (GFM): The Government will provide either double melted AISI-SAE

4340 or maraging, or equivalent, steel bars to the Contractor for use in the performance of this contract.

This property shall be used and maintained by the Contractor in accordance with the Government Property Clause.

Acceptance testing is described above in paragraph (c). The delivery schedule follows:

Scheduled Items Due Dates

Pilot lot specimens delivered to the Charpy Coordinator

Not to exceed 45 calendar days after receipt of the Delivery Order or GFM, whichever comes last

Pilot lot approval from the Charpy Coordinator

Not to exceed 30 calendar days from receipt of pilot lot

Production specimens delivered to the Charpy di

Not to exceed 60 calendar days after pilot l l