One of the great benefits of a community of heat treaters is the opportunity to challenge old habits and look at new ways of doing things. Heat Treat Today’s 101 Heat Treat Tips is another opportunity to learn the tips, tricks, and hacks shared by some of the industry’s foremost experts.
For Heat Treat Today’s latest round of 101 Heat Treat Tips, click here for the digital edition of the 2019 Heat Treat Today fall issue (also featuring the popular 40 Under 40).
Today’s offering includes tips from Quaker Houghton to help you select aqueous quenchant, Pyro Consulting LLC to check your flow, and Nel Hydrogen on how to solve certain compliance issues.
Heat Treat Tip #9
Aqueous Quenchant Selection Tips
1. Determine your quench: Induction or Immersion? Different aqueous quenchants will provide either faster or slower cooling depending upon induction or immersion quenching applications. It is important to select the proper quenchant to meet required metallurgical properties for the application.
2. Part material: Chemistry and hardenability are important for the critical cooling rate for the application.
3. Part material: Minimum and maximum section thickness is required to select the proper aqueous quenchant and concentration.
4. Select the correct aqueous quenchant for the application as there are different chemistries. Choosing the correct aqueous quenchant will provide the required metallurgical properties.
5. Review selected aqueous quenchant for physical characteristics and cooling curve data at respective concentrations.
6. Filtration is important for aqueous quenchants to keep the solution as clean as possible.
7. Check concentration of aqueous quenchant via kinematic viscosity, refractometer, or Greenlight Unit. [Image: Hougton Intn'l Greenlight Unit and/or Houghton Int'l GL Display B] Concentration should be monitored on a regular basis to ensure the quenchant's heat extraction capabilities.
8. Check for contamination (hydraulic oil, etc) which can have an adverse effect on the products cooling curves and possibly affect metallurgical properties.
9. Check pH to ensure proper corrosion protection on parts and equipment.
10. Check microbiologicals which can foul the aqueous quenchant causing unpleasant odors in the quench tank and working environment. If necessary utilize a biostable aqueous quenchant.
11. Implement a proactive maintenance program from your supplier. (Quaker Houghton)
Heat Treat Tip #10
Go with the Flow!
In the absence of specific calibration requirements, how do you know your flow meters are working properly? Certainly, AS9100D requires gauges that can affect fit, form, or function to be calibrated, and Nadcap requires the meters to be correct for the gas used and checked for proper function as part of the PM schedule. Often generator issues can reveal problems with flow meters. Check the meter when the furnace gas is off. If the float does not drop to the -0- mark, it’s an indication that carbon soot has built up inside the chamber of the meter. This condition can be detected early by looking for tiny black carbon particles floating around in the flowmeter oil. Proper PM should include removing the float for cleaning and replacing the float oil regularly. (Pyro Consulting LLC)
Heat Treat Tip #11
Compliance Issues? Try On-Site Gas Generation
On-site gas generation may help resolve compliance issues. Growth and success in thermal processing may have resulted in you expanding your inventory of reducing atmosphere gases. If you are storing hydrogen or ammonia for Dissociated Ammonia (DA), both of which are classed by the EPA as Highly Hazardous Materials, expanding gas inventory can create compliance issues. It is now possible to create reducing gas atmospheres on a make-it-as-you-use-it basis, minimizing site inventory of hazardous materials and facilitating growth while ensuring HazMat compliance. Modern hydrogen generators can serve small and large flow rates, can load follow, and can make unlimited hydrogen volumes with virtually zero stored HazMat inventory. Hydrogen is the key reducing constituent in both blended hydrogen-nitrogen and DA atmospheres—hydrogen generation (and optionally, nitrogen generation) can be used to provide exactly the atmosphere required but with zero hazardous material storage and at a predictable, economical cost. (Nel Hydrogen)
