Nomad Metallurgy, Inc. - Serving Customers across the Carolinas and beyond

Nomad Metallurgy, Inc.
 
"We will travel to the ends of the earth to
meet your material engineering needs!"

 

Home Services Plant Metallurgist Program Failure Analysis Sample Report Links Curriculum Vitae Biography Equipment For Sale

Sample Report

 

At Nomad Metallurgy, Inc. we believe that metallurgical reports should be useful documents: accurate, informative and easy to read. That's why we prepare custom reports for our clients that not only cover all of our findings, but our reports are written in terms you can understand. Our conclusions and recommendations are right up front where you would expect to find them. Then if you want to read the background and study the technical data behind our recommendations, that is readily available later in the report. Contact Nomad Metallurgy today to learn more.

Below is a sample of the type report that is available to our clients.

Printer-friendly version

1/12/2005

 

NAME

ADDRESS

PHONE                                                                                      ANALYSIS REPORT

 

 

Report #:                                                                                Customer PO#:  

 

Background

 Plant Metallurgist Program - Nomad Metallurgy serving the Carolinas

A section ~8” section of 1” wire product with 2 upset headed regions was sent in to be analyzed to determine why the crack occurred.  The wire is identified as Heat # XXXXX, WO # XXXXX and coil # XXXXXXXXXXXXXXXXX, YYYYYYYY  - BW-ZZZZ, and Part # ZZZZZ.  The part as it was received is shown to the right.

 

An additional part of similar manufacturer was received per the author’s request that did not fail in a similar manner.

 

 

Conclusions

 

1.    The only likely cause of the fracture identified prior to inspection of the good part was the poor surface finish of the wire.

2.      The above finding was confirmed by the analysis of the unfractured sample.

3.      The presence of pits in excess of 0.003” from the mill pickling operations provided a stress concentration greater than the strength and ductility of the materials could sustain.

 

Recommendations

 

1.      Create a surface finish requirement for the incoming stock that would preclude pits as deep as 0.003” from entering the facility.  At this point the author lacks the information to recommend an upper limit on surface flaws but it is going to be some where between the 0.0008” and the 0.003”.  

2.      The information needed to guide this limit are:

a)   The percentage of failures in the bad lot.  If it were nearly 100% this would indicate that even close to 0.003” is unacceptable.

b)      The amount of inconvenience and cost the wire fracture is placing on Metal Forge. 

c)      The mill’s ability and willingness to control the surface finish.  If the mill greatly increases the cost to provide such material little is gained.

3.      I suggest that your supplier be contacted and asked to work with you in the creation of a surface finish requirement for this wire. They should also be asked to pull the records on this bad lot to determine any pickling irregularities such as extended times in the bath and the reason for the irregularities.

 

 Observations

 

  1. The part has upset and flattened regions; one has a complete transverse crack while the other has a partial transverse crack.  These are clearly visible in figure 1.

  2.  Plant Metallurgist ProgramThe core hardness of the fractured and unfractured wire away from the headed region is HR45N 63.5 which converts to ~HRB 91. 

  3. Both cracks exhibit a ductile tearing morphology.  This is visible in image to the right of the total fracture surface. 

  4. Both cracks have obvious ignition points as shown by the river pattern on the crack surface. This is indicated in image 2 by the arrow.  

  5. The complete crack has a secondary transverse crack ~0.012” from the failure crack and a longitudinal crack in the center of the fracture region.  The latter of which is visible in the central lower region of figure 2.

  6. The indicated point on the surface at each location is a deep surface pit from a mill pickling operation.  This is shown in Figure 3 below, where the initiation point is below the pen on the lower central region of the picture.

  7. The unfractured part exhibits a much smoother surface with minimal pickling pitting.

  8. The depth of the deepest measured pit in ~1.5 linear inches of cross-sectioned surface on the fractured part measures at least 0.003” deep.  

  9. The depth of the deepest measured pit in ~1.5 linear inches of cross-sectioned surface on the unfractured part measures at most 0.0008" deep.
    Fracture Analysis - Nomad Metallurgy serving the Carolinas










    The affects of this difference can be seen in figures 3 and 4, which are displayed at similar total magnifications.

  10. The surface of the material has a fairly deep-pitted surface structure.  This is visible in figure 3.

  11. The microstructure of both fractured and unfractured material is a ferrite/Pearlite mixture of equi-axised grains of ASTM GS ~8.5 with slight banding, which is more severe toward the center.  This is shown in figure 5 below.

Fracture Analysis - Nomad Metallurgy serving the Carolinas

 

  1. The longitudinal secondary crack was cross-sectioned and it is seen to run along a ferrite to Pearlite band interface as shown in figure 6 to the right.

  2. A review of the certifications provided by the customer indicate that the steel is 1.046” Stress Relieved, Pickled and Limed 1524 from Heat YYYYYY milled by XXXXXXXXX.

  3. No mechanical property data was provided by the drawing house on the shipped product, thus no comparison can be made from historical information.

  4. Chemical Analysis yielded:

 

Chemical Analysis per ASTM E415-99 & E1019-00 in WT%

Element

Tested

Certification

Fracture Analysis - Nomad Metallurgy serving the Carolinas

C

0.28

0.28

Mn

1.54

1.51

P

0.008

0.009

S

0.004

0.004

Si

0.17

0.20

Ni

< 0.05

< 0.05

Cr

< 0.05

< 0.05

Mo

< 0.05

< 0.05

Fe

Bal

Bal

Grade

1524

1524

 

Thank you,

 

 

 

Tom Doggart, P.E.

Director & Principal Engineer

 

 

49 Brockett Road / Niantic, CT 06357
Phone 704-517-3038 / FAX 860-739-3775 / E-Mail info@nomadmet.com
Site Design by
SpyderWeb Concepts