CHTE UPDATE
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A D V A N C E D M A T E R I A L S & P R O C E S S E S | F E B R U A R Y / M A R C H 2 0 1 7
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Eighteen years ago, the Center for Heat Treating Ex-
cellence (CHTE) was founded with the goal of bringing the
industrial sector and university researchers together to
find solutions to real-world problems. Today, CHTE—locat-
ed at Worcester Polytechnic Institute (WPI) in Massachu-
setts—has 19 members from all areas of industry working
together with WPI researchers to improve both heat treat
and thermal processing methods worldwide.
The organization has an impressive body of work.
It has completed more than 20 projects that cover every-
thing from induction tempering, thermal processing, and
distortion to gas and oil quenching, energy efficiency de-
termination, furnace modeling, alloy life extension, gas
and vacuum carburization, and more.
DISTORTIONANDRESIDUALSTRESSRESEARCH
CHTE’s latest project is called “Guidelines for Assess-
ing Distortion and Residual Stress.” According to Richard
Sisson, George F. Fuller Professor of Mechanical Engineer-
ing and CHTE technical director, this is an area of huge con-
cern; companies spend millions of dollars scrapping parts
that become distorted during the heat treat process, in ei-
ther the heating or cooling period. Further, some materials
have stored residual stress, which causes distortion and
compromises part integrity.
Steve Ferdon, director of engineering technology in
the fuel systems business at Cummins Inc., and current
chair of CHTE’s board of directors, is excited about this
project. “Because residual stress and heat treat distortion
are recurring frustrations for the industrial membership,
we have had a truly open and collaborative effort to devel-
op the scope of work for this project,” says Ferdon. “Global
players in the aerospace, industrial equipment, transpor-
tation, automotive, heat treat equipment, and integrated
computational materials engineering (ICME) industries are
engaged and will provide technical guidance and resourc-
es throughout the project. The expected outcome will be
development of precompetitive data, process design prac-
tices, and analytical tools that will have a real, practical,
and immediate benefit to members’ bottom lines.”
Key project objectives include:
1. Determining the most important heat treating
process parameters that impact residual stress
and distortion in industrial parts.
2. Developing a ranking of these processing
parameters based on their impact.
3. Providing processing guidelines to control
residual stress and distortion.
This is a big undertaking for CHTE. The center is now
compiling a list of parameters to start putting boundaries
on the project, which will further refine the scope. Currently,
the project is in the modeling and simulation phase with the
expectation that research testing will begin in June (Fig. 1).
RESEARCHOF INTEREST
What makes CHTE unique from other collaborative
efforts is that members select the research projects. In
December 2016, CHTE andWPI researchersmet todetermine
the direction of additional studies. Based on their input, the
project selection committee determined that many compa-
nies are facing similar areas of concern, thus defining key
topic areas that the center is considering for future research:
•
Processing modeling and data validation
is of key
importance. This aligns well with the ATC TMI road
map that was sponsored by NIST and ASM Interna-
tional and published in 2015. In this roadmap, a
significant focus is developing tools for simula-
tion. CHTE has two member companies—Thermo
Calc and DANTE Solutions—that both focus on ICME,
and this is becoming more important as a tool to
understand complex material systems before
investing in expensive physical models, prototypes,
or processes. Many of the CHTE studies will contrib-
ute to the datasets available for ICME studies.
•
Bainite
is an emerging topic of interest among the
membership. OEMs desire a better understanding
Fig. 1 —
Cylinders of several steel grades were austenitized and
quenched in water. The residual stress in hoop direction as pre-
dicted by DANTE, (a) Pyrowear53, (b) AISI 4140 steel, and (c) AISI
52100 steel. Compressive stress in the hoop direction developed
in the exterior part for Pyrowear53 and AISI 4140 steel. Tensile
stress developed in the 52100 steel. Variation is due to differences
in martensite start temperature.
(a)
(b)
(c)
CHTE RESEARCHERS TACKLE REAL-WORLD
HEAT TREAT PROBLEMS