May/June_AMP_Digital

FEATURE 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 | M A Y / J U N E 2 0 1 8 3 4 2 reactions that may occur. For residual stress and dis- tortion prediction, these properties include thermal, mechanical, and phase transformation kinetics of the phases that are present at any time during the process. • Third, the conditions during the heat treatment steps must be known. ○ ○ For furnace heating, this includes furnace ambient temperature as well as convection and radiative heating. ○ ○ In the case of induction heating, the electromag- netic properties of the workpiece and the eddy currents generated by the inductor as affected by the frequency and power must be known. Joule heating that occurs within the workpiece during the induction process must be calculated. ○ ○ During quenching, the interaction between the part(s) and the quenching mediummust be accu- rately described by surface heat transfer coefficients and ambient temperature OR local heat flux and ambient temperature. By gathering these data and assembling them into a process model, valuable insights about the heat treatment being simulated can be gained. However, simulation isn’t free. Costs include the software and hardware required to run the simulation, the engineering time to build and run the model and analyze the results, and the effort required to gather the process and material data. Validation of the sim- ulation capability and required training costs should also be considered. What also needs to be considered is the cost of the al- ternative—that is, continuing the use of trial-and-errormeth- ods to solve existing problems or develop heat treatments for newproducts or newalloys. I believe that we have passed the tipping point where the costs of not employing simula- tion exceed the costs of applying heat treat simulation. Meth- ods have matured, sufficient validations using actual case studies exist, and it is time to move the industry forward. B. Lynn Ferguson, FASM Founder and President DANTE Solutions Inc. SIMULATE HEAT TREAT PROCESSES? YOU BETCHA D an Herring, the ac- claimed “Heat Treat Doctor,” recently wrote that one of his New Year’s resolutions is to “convince ev- ery heat treater to purchase anduse simulation software.” His focus is on carburizing processes where the simula- tion software would be used to determine process recipes or to control the process it- self, and for these technologies he states that the technology is “proven and robust.” At my company, we go further and say that all aspects of heat treatment are ripe for simulation, including analysis and prediction of events during all modes of hardening steel components. While many captive heat treat shops actively use pro- cess modeling—or at least are interested in the technology— many commercial shops have steered clear of simulation technology. Usually, they only turn to modeling when a heat treat problem has cost them money. Following the good doctor’s resolution, it’s time for all heat treaters to grab onto some type of simulation technology that can benefit their company. Beyond troubleshooting, heat treat process simulation forces users to do several things in order to reap the many benefits of modeling: • First, the process to be simulated must be well characterized, meaning accurate time, temperatures, and process conditions (atmosphere, etc.) must be documented. What the part experiences during heat treatment must be known and described in the model if simulation is to be accurate. • Second, the properties of the steel being heat treated must be known and these properties must include the physics of the process steps being simulated. For carburization, this mainly covers thermal and carbon and/or nitrogen diffusion and the metallurgical GUEST DITORIAL