API6A718 Work Group UpdateFebruary 6, 2014

API6A718 Work Group MeetingJanuary 30, 2014

Brinell to Rockwell Conversion

Current API6A718

Current Draft - Oct. 8, 2013

Situation

• Industry experience along with data provided by Foroni, Carpenter, VDM and Bohler demonstrates that Table 3 of ASTM E140 is inaccurate for the alloys of interest.

HBW vs HRC for PH Nickel Alloys

290

310

330

350

370

390

410

430

32 33 34 35 36 37 38 39 40 41 42 43

Rockwell C

HB

W

ForoniCTCVDMBohlerE140

MR0175 provides HRC limits and permits users to establish conversion tables.

Part 3, para. 6.2.1

“The conversion of hardness readings to or from other scales is material-dependent. The user may establish the required conversion tables.”

ASTM E10 & E18

“conversions are, at best, approximations and, therefore, should be avoided except for special cases where a reliable basis for the approximate conversion has been obtained by comparison tests.”

ASTM E140

Table 3 - “intended to apply particularly to the following: nickel-aluminum-silicon specimens”

Note 1 - “most of the values were generated using a steel ball while the tungsten carbide balls used today will produce different values.”

Conversion formula and table generated from Foroni and Carpenter data

API CSOEM meeting on Friday 24 January 2013, Sterling Lewis, the Chairman of API SC6, submitted a funding proposal for the round robin tests necessary to develop the data required for two ASTM hardness correlations.  These two hardness correlations will cover Nickel-Chromium-Molybdenum alloys and low carbon martensitic stainless steels.

Proposals

A.Ballot 6A718 with Brinell values from ASTM E140 table 3

B.Ballot 6A718 without Brinell requirements for the additional alloys. Allow users to establish tables in accordance with MR0175

• Revisit once ASTM has established table for Nickel-Chromium-Molybdenum alloys

Resolution by unanimous vote was to eliminate HBW values until an appropriate conversion table can be developed in conjunction with ASTM

UNS number Material Designation

Minimum Hardness a

HRC (HBW)

Maximum Hardness b

HRC (HBW)

N07716 120K 32 (--d) 43 (--d)c

140K 34 (--d) 43 (--d)c

N07718 120K 32 () 40 ()

140K 32 () 40 ()

N07725 120K 32 (--d) 43 (--d)c

N09925 110K 26 (--d) 38 (--d)c

N09935 110K 24 (--d) 34 (--d)c

N09945 125K 32 (--d) 42 (--d)c

140K 34 ((--d) 42 (--d)c

d - The conversion of hardness readings to or from other scales is material-dependent. Conversion tables maybe used upon agreement between purchaser, manufacturer and end user..

Hardness Testing Frequency

Current API6A718

• Each piece of production material and each QTC shall be hardness tested on or near the surface using the Brinell (10 mm ball, 3000 kgf) method per ASTM E 10 or the Rockwell C method per ASTM E 18 after the final heat treatment cycle. Each piece of production material and each QTC shall have a minimum of one hardness

test.

MR0175 section 6.2If hardness measurements on parent metal are specified, sufficient hardness tests shall be made to establish the actual hardness of the CRA or other alloy being examined. Individual HRC readings exceeding the value permitted by this part of ISO 15156 may be considered acceptable if the average of several readings taken within close proximity does not exceed the value permitted by this part of ISO 15166 and no individual reading is greater than 2 HRC above the specified value. Equivalent requirements shall apply to other methods of hardness measurement when specified in this part of ISO 15156 or referenced in a manufacturing specification.

Current Draft - Oct. 8, 2013a. Each piece of production material shall be hardness tested on or near

the surface using the Rockwell C method per ASTM E 18 or the Brinell (10 mm ball, 3000 kgf) method per ASTM E 10 after the final heat treatment cycle. For Rockwell C-scale testing three adjacent indentations shall be made and the mean hardness reported. No individual hardness number may be greater than 2 HRC units above the maximum specified hardness number. For Brinell testing at least one indentation shall be made. In case of dispute, the Rockwell C-scale method shall be the referee method.

b.Cross-section hardness testing shall be performed on each QTC using the Rockwell C method per ASTM E 18 Three adjacent indentations shall be made near the surface, three adjacent indentations shall be made at ¼ thickness and three adjacent indentations at the center. The mean hardness at each location shall be reported. No individual hardness number may be greater than 2 HRC units above the maximum specified hardness number.

c. Rounding of test results to determine conformance to specification shall be in accordance with ASTM E29

Agreed upon resolution is to only require one Brinell test per piece and include the wording below in red

a. Each piece of production material shall be hardness tested on or near the surface using the Rockwell C method per ASTM E 18 or the Brinell (10 mm ball, 3000 kgf) method per ASTM E 10 after the final heat treatment cycle. For Rockwell C-scale testing three adjacent indentations shall be made and the mean hardness reported. No individual hardness number may be greater than 2 HRC units above the maximum specified hardness number. For Brinell testing one indentation is sufficient. If the results do not satisfy the applicable requirements, additional adjacent Brinell tests may be taken and all additional indentations shall meet. In case of dispute, the Rockwell C-scale method shall be the referee method

Reporting of Hardness Values

Agreed upon resolution is

For each piece of production material the mean value of surface hardness test shall be reported. All hardness indentations taken on QTC shall be reported.