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# CHAL-AMB2018-02-CR

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### **Results Description for CHAL-AMB2018-02-CR: Cooling Rate of Solidifying Material**

**1. Overview of Results**

The following tables and associated links summarize the data to be used for CHAL-AMB2018-02-MP: Melt Pool Geometry-Melt Pool Length and CHAL-AMB2018-02-CR: Cooling Rate of Solidifying Material, measured on the commercial build machine (CBM) and Additive Manufacturing Metrology Testbed (AMMT) using in-situ thermographic methods.  Melt pool width (CHAL-AMB2018-02-MP: Melt Pool Geometry-Melt Pool Width), measured ex-situ via confocal microscopy, can be found here.

**Note 1:** The ex-situ measurements for AMB2018-02, including topography, grain shapes, and structure were made on the samples fabricated on the AMMT.  Ex-situ measurements on the CBM samples will be provided at a later time.

**Note 2:**  Laser power calibration on the AMMT was found erroneous after the single tracks were fabricated.  A commanded power of 150 W resulted in true power of 137.9 W, and commanded power of 195 W resulted in 179.2 W.  The true laser power on the AMMT which fabricated the test samples is noted in the tables.

**Note 3:** It is understood by the authors that the melt pool cooling rate measurements differ drastically between the CBM and AMMT measurement systems, despite great effort to ensure experiment parameters and controls for both systems were as similar as possible.  Additional validation experiments were conducted to deduce any potential experiment setup or measurement error.   At the time of publication (5/18/2018), the source of discrepancy is yet undetermined.  Despite this, the authors felt that openly presenting and acknowledging this discrepancy is of greater scientific value than withholding results from one or both experiments.  Discussion of this discrepancy will be provided at the 2018 AM-Bench conference, further updates to this site, and further investigations or publications.

----

**2. Cooling Rate of Solidifying Material**

Table 1 provides cooling rate values determined from in-situ thermographic measurements on the CBM.  Cooling rate is calculated using the method defined in 3.1 of the MB2018-02 test description.  This definition calculates cooling rate from the assumed solidus temperature of 1290 oC down to 1000 oC (difference of -290 oC). In addition, the cooling rate from 1290 oC to 1190 oC (difference of -100 oC) is presented for comparison with the results from the AMMT experiments. Associated temperature profiles, measurement details, and additional results of interest can be found here.

Table 1: CHAL-AMB2018-02-CR: Cooling rate of solidifying mat erial measured on the CBM, measured from 1290 oC to 1000 oC. and 1290 oC to 1190 oC

Table 2 provides melt pool length values determined from in-situ thermographic measurements on the AMMT.   Cooling rate is calculated using the method defined in 3.1 of the AMB2018-02 test description.  Due to a higher temperature calibration range on the AMMT camera, the cooling rate is calculated from the assumed solidus temperature of 1290 oC down to 1190 oC (difference of -100 oC).  Associated temperature profiles, measurement details, and additional results of interest can be found here.

Table 2: CHAL-AMB2018-02-CR Cooling rate of solidifying material measured on the AMMT, measured from 1290 oC to 1190 oC.

Additive manufacturing

## Contacts

                -  Lyle E. Levine  lyle.levine@nist.gov      (301) 975-6032   
                -  Brandon Lane  brandon.lane@nist.gov      (301) 975-5471   

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