The emails below from Dr. George Totten and Dr. Nik Kobasko below announce the passing of Dr. Hans Tensi. These emails also declare why scientists such as Dr. Tensi, Dr. Totten, and Dr. Kobasko are the founders [and] fathers of modern heat treating metallurgy – what I call the 3rd Generation of Heat Treating. Dr. Kobasko, nd his Ukrainian and Russian associates worked with scientists such as Dr. Totten [and] Dr. Tensi as well as many other heat treating metallurgists and part makers from the USA, Germany and [other] European countries before the fall of the Soviet Union’s Iron Curtain. They all tried to understand the many mechanisms at work in heat treating and especially quenching distortion.
Dr. George Totten and Dr. Kobasko worked with the late Dr. Hans Tensi to try to quantify the modern quench cooling processes using various quenchants and agitation rates; their early work to characterize the many polymer, water-salts and oil quenchants is still in use today. Dr. Tensi was the creator of the Tensi Quench Probe, a probe used for gathering thermocouple data for quench cooling curves for characterizing various quenchants in the lab for constructing better quench cooling curves. The Tensi probe helped to identify and to quantify the three phases of quench cooling – “film” boiling, “nucleate” boiling and “no boiling” – uniform convection cooling and the relationship of agitation rates to part distortion caused by non-uniform quench cooling.
Early 20th-century heat treaters like my father, Prosper Powell, and Dr. Kobasko, Dr. Tensi and Dr. Totten developed heat treating methods from a First Generation of “Blacksmithing Arts” (with a bucket of quench water and horse urine salts at a forge) to 2nd Generation Heat Treating Sciences with modern quench oils and polymer/water quenchants. 2nd Generation heat treaters also introduced thermocouple temperature controls and oxygen probe atmosphere controls as well as traditional forms of “uniform” controlled quenching with various liquid quenchants, molten salts (Martemper and Austemper) and high pressure gas quenching; all to avoid “The faster the quench rate, the more likely you will blow up the part!”
This generation of heat treaters all began a process of trying to measure, quantify and ultimately to control “uniformity and intensity” of both heating and quenching during heat treating. Their 2nd Generation Heat Treating methods and equipment led to a full understand of the relationships between both the “Left Side” and the “Right Side” of Dr. Kobasko’s “Quench Cooling Rate versus Probability of Part Cracking” – the Bell-Shaped Curve that Dr. Kobasko and his IQ Technologies’ colleagues, Dr. Michael Aronov and I, introduced to the USA at Akron Steel Treating Company in 1999 with the first IQ-2 batch quenching unit. (Unfortunately, we still do not have a reliable, in situ quench uniformity probe or a way to capture a part’s “quench cooling signature” in real time. . . but IHTS Consultants are working on it!)
Our last Generation of 2nd Heat Treaters also paved the way for a 3rd Generation of heat treat process modeling; we created the fundamentals of FEA and CFD modeling for both a heat treating process and equipment design that is linked to heating and cooling on a “Grainular” level of part metallurgy. 3rd Generation Heat Treating is what Integrated Heat Treating Solutions’ Consultants, and our many other Teaming Partners, are trying to bring to everyday heat treating practice for Industry 4.0. Joe Powell, Akron Steel Treating. Photo credit: ASM International
We are sorry to see the passing of Dr. Tensi, but will always remember the groundbreaking work that he and his colleagues did in the last century for heat treating in the 21st Century.
