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STATEMENT OF WORK

TITLE: Procurement of 4340 Steel for Charpy Program LAB REQUESTING SERVICE: Applied Chemicals and Materials Division

BACKGROUND INFORMATION

The National Institute of Standards and Technology (NIST), Material Measurement Laboratory, Applied Chemicals & Materials Division (ACMD) requires American Iron and Steel Institute-Society of Automotive Engineers (AISI-SAE) 4340 steel bars. They will be used to produce high quality Standard Reference Materials SRMs that are precisely machined and heat treated for use as American Society for Testing and Materials (ASTM) Charpy V-notch reference specimens [ASTM E23, “Standard Test Methods for Notched Bar Impact Testing of Metallic Materials”].

Charpy V-notch specimens are sold by NIST as standard reference materials to certify the performance of Charpy V-notch impact machines. The steel must be of the highest quality possible to ensure uniform impact properties and long term stability (resistance to aging) of the reference material. The American Society for Testing Materials specification E23 describes this test and these specimens.

I. SCOPE OF WORK

NIST expects to have a supply of 4340 steel supplied that meets all the technical specifications and can be used to successfully produce high quality NIST SRM specimens for verifying Charpy machines according to ASTM E23.

II. SPECIFICATIONS

Compositional and melting requirements:

1. The Contractor shall provide AISI 4340 steel bars, from a single heat to minimize compositional and microstructural variation. Because steel plants produce steel in different heat sizes (inherent to their facilities), NIST will allow some flexibility in our contract by bracketing the quantity of the steel to be purchased and setting a maximum of $100,000 for the purchase. NIST prefers to purchase the maximum quantity of steel possible.

2. The steel shall be produced using either a double-vacuum-melting procedure (vacuum-induction-melt vacuum-arc-remelt, VIM-VAR), or arc furnace melting followed by argon-oxygen-decarburization (AOD) refining to produce electrodes which are vacuum arc re-melted (ARC-AOD-VAR).

3. The steel shall meet the compositional requirements of AISI-SAE alloy 4340. Refer to http://www.steelforge.com/alloy-steel-4340/ for compositional information.

4. The steel must also meet the stricter requirements of AMS 6414 (see http://standards.sae.org/ams6414/), which describes steel production by a vacuum-melting procedure.

5. The ACMD also requires that the phosphorus, sulfur, vanadium, niobium, titanium, and copper contents of the steel to be low. The maximum concentrations (in mass %) allowed for these elements shall be: (1) P = 0.010, (2) S = 0.010, (3) V = 0.030, (4) Nb = 0.005, (5) Ti = 0.003, and (6) Cu = 0.35.

6. The composition shall be certified using standard analytical procedures (such as optical emission spectroscopy or x-ray fluorescence), and the equipment is calibrated by standards traceable to NIST. The composition shall be measured at the top and bottom of the re-melted ingot. These two measurements shall be included in the documentation with the order, meet our compositional requirements, and meet the limits on residuals given above. Deviations between the two measurements (in mass percent between the top and bottom of VAR ingot) cannot exceed 0.030 for C, Si, and Mo; 0.10 for Mn; 0.030 for Cr; 0.050 for Ni; 0.003 for P; and 0.001 for S.

7. The ingots shall be forged, rolled to billet, conditioned, then hot rolled to bar (if an alternate process has not been mutually agreed upon). The goal of the processing is to have bar from one procurement to have inclusion distributions and sizes that are similar to batches produced from other procurements. With this objective in mind we require the steel to be processed in a manner agreed upon prior to the processing of the steel, such as:

a. VAR ingots at 1093 C (2000 F) are forged to 12 by 11 inch billets that are rolled to 2 ¼ inch diameter billets

b. These billets are then solution annealed (1100 C, 2012 F for 1 hour, minimum) prior to rolling to ½ inch square bar (1093 C, 2000 F).

c. If the solution treatment is performed as a separate process, controlled cooling (fans, quenching, etc.) is required down to a temperature of 500 C (930 F).

d. If the solution treatment is performed as part of the re-heating cycle prior to rolling, the process shall be described in adequate detail to indicate/estimate holding and cooling times.

8. The bar shall be finished to 0.50 inch square bar (+0.15 inch, -0.00 inch).

a. The corner radius of the finished bars cannot exceed 0.03 inches.

b. The microstructure shall be uniform through the thickness, with a maximum acceptable grain size of ASTM number 7.

c. In other attributes (decarburization, segregation, surface condition, etc.), the steel must be suitable for use as 10 mm square Charpy V-notch specimens.

9. The 0.50 inch bar shall be fully annealed to a hardness of RB-95 max.

a. The bar shall be annealed at 1550 F (850 C) and for 1 hour, furnace cooled at 10 C/hr (50 F/hr) to 315 C (600 F), then air cool to room temperature.

b. It is critical to produce a uniform hardness bar (no hard spots), because hard spots result in significant machining issues.

c. The ACMD will accept alternate heat-treating schedules by mutual agreement.

10. The bar is required to be machine straightened (for twist and bow), and shipped in lengths of no more than 6 feet.

III. PERIOD OF PERFORMANCE

Delivery is due to NIST within 10 months of receipt of order.

IV. PLACE OF PERFORMANCE

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

V. GOVERNMENT FURNISHED PROPERTY

No government-furnished property is provided.

VI. DELIVERY INFORMATION

The 4340 steel shall be delivered to: NIST Div 647, Attn: Will be given at time of award, 325 Broadway, MS 647 Boulder CO 80305.

The bars shall be packaged in bundles identified with reference to the ingot/billet position from which it was processed. The individual boxes/packages that are shipped shall weigh less than 2000 lb each (our fork lift capacity).

The Contractor shall include documentation stating how the steel was processed, how the steel was formed, results on chemistry grain size, and relevant mechanical properties.

VII. INSPECTION AND ACCEPTANCE

Upon receipt, documentation will be reviewed for acceptability. The material will be reviewed for squareness, and identification of bundles within the shipment will be reviewed for completeness and clarity. The material will be accepted following these reviews within 1 week of delivery of the order to NIST Boulder.

If bar is found to be too hard for machining (harder than our requirement of RB-95 max), the vendor will be charged to soften the bar so it meets specifications.