Charpy LL_HH SRM 4 Lots SOW Final.pdf

Charpy SRM LL_HH 4 Lots SOW Page 1 of 6

Charpy SRM LL_HH 4 Lots Statement of Work

Background: The NIST Standard Reference Materials (SRM) 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) to industry to indirectly verify Charpy impact testing machines in accordance with American Society for Testing and Materials (ASTM) E23 and ISO 148-2. NIST Charpy SRMs are required in various industrial standards and specifications to verify the performance of industrial impact machines to assure a common measurement base for purposes of trade and commerce. All measurements made by the United States and international industry under the ASTM E23 test standard are traceable to NIST through these SRMs. These Charpy Specimens are the highest demand SRMs distributed by NIST.

To produce Charpy specimens, steel blanks are heat treated in a batch. The entire heat-treated batch, which is typically around 1900 specimens, is designated as the production lot. In addition, a pilot lot of 100 specimens drawn at random from this production lot is selected for acceptance testing, as discussed herein.

Deliverables Four (4) SRM Charpy specimen lots (1900 specimens/lot):

3 Low-Energy Lots (LL-185,186 & 187) 1 High-Energy Lot (HH-189)

Special Qualifications Due to the exacting specifications of the Charpy Specimens and NIST’s need to supplement specimens in short supply, three qualifications are required:

• Contractor shall be pre-qualified by NIST through a Machining Qualification Program.

• Contractor shall be on the Qualified Manufacturer’s List (QML), maintained by the NIST Charpy coordinator.

• Contractor shall have delivered at least one successful Charpy production lot to NIST.

Delivery Schedule

See Delivery Schedule and Scheduled Due Dates.

Place of Performance The work performed under this contract will be performed at the Contractor’s facility.

Government Furnished Material (GFM) The Government will provide AISI-SAE 4340 steel bars to the Contractor for use in the performance of this contract. GFM delivery will be tracked and applied to the initial pilot lot delivery schedule as appropriate. The Contractor shall notify the Charpy Coordinator when the level of GFM is close to 500 lbs., so that additional material can be shipped.

Specifications The Contractor shall determine the exact heat treatment needed to produce the required energy level. The entire heat-treated production lot shall be made from the same heat of steel. No other material shall be mixed with the production lot during processing. All specimens shall be machined to the following dimensions and tolerances (see Figure 1).

(1) All specimen surfaces, except the ends, shall be ground to the finished dimensions. Any machining technique can be used for the specimen ends, as there are no requirements on their surface finish.

(2) The length of each specimen shall be 55 mm 00.0

30.0 − (2.165 in. 00.0

012.0 − in.).

(3) One end of each specimen (10 mm × 10 mm surface) shall be stamped or etched with a lot code and a serial number; the other end (10 mm × 10 mm surface) shall be stamped or etched with the letters “NIST.” “Marking Deliverables” for the specifics.

(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’ (90° ± 0.15°).

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(5) The surface roughness (Ra) shall be 1.6 µm (47 µin.) or less on the notched surface and opposite surface, and 3.2 µm (100 µin) or less on the other two longitudinal surfaces.

(6) Notch Specifications:

• The notch shall be centered at 27.5 mm ± 0.20 mm (l.083 in. ± 0.008 in) from either end.

• The material thickness below the base of the notch (ligament size) shall be 8.0 mm ± 0.025 mm (0.315 in. ± 0.001 in.).

• The notch shall be perpendicular to the longitudinal axis of the specimen to 90° ± 9’ (90° ± 0.15°).

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

0.001 in.).

• Specimen notches shall be ground on a surface grinder. Machining with a fly cutter, multi-tooth cutter or broach is NOT acceptable. In general, the use of an electrical discharge machining (EDM) process is not allowed, unless the notch profile is found acceptable based on visual inspection of multiple specimens by the Charpy Coordinator. Should the EDM notch profile be judged unsatisfactory, grinding will have to be used instead. Overheating or cold working the material adjacent to the notch or side groove shall be avoided. For grinding, the next to last cut 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 operations. Notches shall be deburred.

Figure 1: Specimen Dimensions (millimeters).

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, all dimensions shall be within the stated tolerances.

(3) For each measured specimen, hardness readings taken at opposite ends of the specimen shall not differ by more than 1.5 Rockwell C Hardness (HRC). The hardness value of each specimen will be the average of the two measurements taken at opposite ends. The coefficient of variation of all hardness values (ratio between standard deviation and average value) shall not exceed 2 %. If either, or both, of these hardness requirements are not fulfilled, the Charpy Coordinator will determine whether the lot shall be rejected before testing the specimens.

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

(5) The recommended ranges for the average absorbed energies of Charpy indirect verification specimens are as follows:

(a) Low-energy specimens: between 13.0 J and 20.0 J (9.5 ft.-lbf to 15.0 ft.-lbf).

(b) High-energy specimens: between 85.0 J and 140.0 J (63.0 ft.-lbf to 103.0 ft.-lbf).

The Charpy Coordinator will determine if lots outside of the recommended ranges can be accepted.

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(6) Specimens at both energy levels shall meet the following requirements.

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

𝑛𝑛𝑆𝑆𝑆𝑆 = �3𝑆𝑆𝑝𝑝

𝐸𝐸

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

𝑆𝑆𝑝𝑝 = �𝑠𝑠1

2+𝑠𝑠2

2+𝑠𝑠3 where sl, s2, and s3 are the standard deviations of the three reference machines.

The sample size, nSS, shall not exceed 5.0.

(b) The number of outliers shall not exceed 10 % of the number of specimens tested (4 is the maximum when 75 specimens are tested). The outlier analysis is performed using box-and-whiskers plots. 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 alternative outlier analysis can be performed by means of Grubbs’ test (extreme studentized deviate) with α = 0.05. An outlier will not removed from analysis unless it shows physical evidence of jamming, material flaws, or other reason for atypical behavior.

(7) If the specimens from a pilot lot fail to meet any of the above requirements, the Contractor will be asked to provide an additional pilot lot, unless three pilot lots have already been furnished.

(8) If the specimens from a production lot fail to meet any of the above requirements, the Charpy Coordinator will determine if it is in the Government’s best interest to have the contractor take corrective action with regards to the resubmission of the failed production lot.

Marking and Packaging Deliverables

(1) All specimens shall be marked in a clear and legible manner as follows.

Individual specimens shall be stamped, engraved, or etched on one end (10 mm × 10 mm surface) with one of the following lot identifications:

Low Energy: LL NNN High Energy: HH NNN where "NNN" is the lot number, and “LL” or “HH” correspond to low-energy and high-energy lots respectively. The Charpy Coordinator will add in the lot numbers (NNN).

(2) The specimen serial number shall be stamped, engraved, or etched below the lot ID number (NNN).

Serial numbers shall begin with the number 1 and end with the last number produced within the production lot. For example: “HH 195” (top: lot ID - can be one or two lines); “279” (bottom:

specimen serial number.) (Figure 2)

The opposite end (10 mm × 10 mm surface) shall be stamped or etched with the letters: “NIST.”

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Figure 2: Charpy Specimen Marking Example

(3) Any etching, stamping, engraving, scribing, etc., technique may be used, as long as the specimen marking is of good quality and clearly readable.

(4) Shipping containers shall be marked as follows: contract number, lot id, steel type, and unique GFM heat number shall be placed on or adjacent to all exterior mailing or shipping labels of specimen shipments.

(5) When a pilot or production lot has shipped, the Contractor shall inform the Charpy Coordinator and provide the tracking number(s) for the shipment(s).

(6) Specimens shall be securely packaged and protected from rusting.

(7) Packages shall weigh no more than 45 pounds each.

Pilot Specimen Testing and Acceptance Pilot lot specimens shall be drawn from predetermined locations in the heat treatment baskets, as communicated by the Charpy Coordinator, to assure consistency (exceptions may be made for continuous heat treatment processing).

See above for acceptance testing procedures. If the pilot lot fails to meet the specifications in this contract, the Charpy Coordinator will reject it and may suggest re-heat treatment of the batch based on the test outcome. If new steel is to be used, it will be provided to the Contractor by the Charpy Coordinator. The remaining specimens from the failed lot are to be returned to NIST at the Contractor's expense. NIST will destroy the specimens. No more than three attempts at producing a successful pilot lot will be permitted.

Sampling plan for NIST pilot lots

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

(2) If more than one basket is used during heat treating, an equivalent number of specimens from each basket shall be provided in the pilot lot.

(3) Specimens from predetermined locations, so as to sample every position in the basket(s), shall be provided in consultation with the Charpy Coordinator.

(4) The Contractor shall provide a list of specimens (serial numbers) taken from each basket’s location to the Charpy Coordinator. The relative position of each specimen in the basket (top, middle, bottom, etc.) and in the furnace shall be clearly identified.

Production Specimen Testing and Acceptance Specimens shall be randomly drawn from the production lot by the Charpy Coordinator and tested. If the production lot specimens fail to meet the requirements, the Charpy Coordinator will reject the lot unless they determine that the Contractor can implement corrective actions. Production lots that fail because of microstructure, hardness, and/or sample size, will be rejected, and the Contractor will only be compensated at 30 % of the production lot value. Production lot failure caused by unacceptable specimen dimensions will not be compensated.

The Charpy Coordinator will determine if it is in the Government’s best interest to have the Contractor take corrective action regarding resubmission of failed production lots. NIST will destroy all specimens from failed lots, Charpy SRM LL_HH 4 Lots SOW Page 5 of 6 and the lot number will be recorded as invalid for SRM purposes.

Defective Government Furnished Material (GFM) If the Government determines that pilot or production lot failure is due to defective GFM, the Contractor shall be compensated at 30 % of the entire lot value (pilot + production) as a lot processing fee. Further, the Contractor will be compensated at $25.00/specimen for each fully machined specimen produced at the time of Government notification to the Contractor about the defective GFM. “Fully machined specimens” include all specimens already delivered to NIST for acceptance testing for that lot, for example multiple pilot lots of 100 specimens each. Fully machined specimens that have not yet been delivered to NIST (for example, pilot lot specimens in preparation) must have been authorized for production by

NIST.

The exact number of fully machined specimens must promptly be communicated by the Contractor to the Charpy Coordinator. Maximum compensation will be capped at the entire lot value.

Delivery Schedule The delivery schedule is dynamic and will be adjusted based on the success or failure of the pilot and production lots. Due to an urgent requirement for Charpy SRMs, the delivery schedule reflects 15 days for the pilot lot and 30 days for the production lot.

The Contractor can begin work on assigned lots at any time, and lots can be worked on in parallel. Early delivery is acceptable.

Scheduled Due Dates

Scheduled Items Due Dates

Initial pilot lot Due 15 days from receipt of the award or Government Furnished Material (GFM), whichever comes last

Pilot lot inspection by Charpy Coordinator Not to exceed 7 calendar days from receipt of lot

Resubmission of failed pilot lot Not to exceed 15 calendar days from pilot lot rejection notice

Production lot delivery Not to exceed 30 calendar days from pilot lot acceptance notice

Production lot inspection by Charpy Coordinator Not to exceed 7 calendar days from receipt of lot

Resubmission of failed production lot Not to exceed 15 calendar days from pilot lot rejection notice

Subsequent pilot lot (next lot in order) Not to exceed 15 calendar days from production lot acceptance

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Sample Dynamic Schedule (unit: calendar days)