Classic Article: Continuous Carburizing by Gas
August 12, 2016
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Despite the growth of alloy steels and special means of surface hardening, the ancient art of carburizing steel remains one of the fundamental operations in the manufacture of machine parts. It retains its popularity because it enables the workman to start with a material that can be easily machined, and end with an excessively hard and desirable surface for resisting wear, retaining ductile metal underneath with sufficient strength and shock-resisting properties to stand up to severe duty.
As is well known, most carburizing is done by the time-honored method of packing the steel with carbonaceous materials in suitable containers, covering it in such a way as to prevent infiltration of furnace gases, then raising the temperature to a suitably high point, and holding it there for some hours, depending upon the depth and character of case desired. Carburizing by this means is dependent on a number of factors, many of which arise from the character and uniformity of the compound; great care must therefore be vised in handling the compound to obtain satisfactory results. At best, there are still many variables that are hard to control and results that are difficult to explain. It has been felt for many years that this metallurgical process is too cumbersome and dirty to fit in well with modern manufacturing practice. To those who have studied the matter, it seemed that the desired improvement could be had in a process for carburizing with an externally prepared gaseous atmosphere. Such an atmosphere could be clean, of uniform composition, easily controlled, always fresh and theoretically desirable.
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Despite the growth of alloy steels and special means of surface hardening, the ancient art of carburizing steel remains one of the fundamental operations in the manufacture of machine parts.
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One Minute Mentor: Influence of Chromium on Ferritic Stainless Steels
May 26, 2016
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Ferritic stainless steels are quite similar in their mechanical behavior to carbon steel. The main influence of chromium is to produce some solid solution hardening. As noted, intermetallic phases may increase hardness (sometimes usefully) and decrease ductility, notch toughness, and corrosion resistance. For example, the graph shows the hardening effect of alpha prime.
Volume 4D, Heat Treating of Irons and Steels ⇒ Heat Treated High-Alloy Steels ⇒ Heat Treating of Ferritic Stainless Steels ⇒ Properties
Ferritic stainless steels are quite similar in their mechanical behavior to carbon steel.
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One Minute Mentor: Effects of Different Cooling Rates on Corrosion-Resistant Tool Steels
March 18, 2016
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The graph shows the effects of different cooling rates on the toughness properties (un-notched samples) of AISI 420 and nitrogen-alloyed M333 tool steels.
The cooling parameter λ8/5, which is the cooling time from 1470° to 930°F in seconds, divided by 100, is used. Besides the general trend of falling toughness with rising cooling time, it is clearly evident that the nitrogen-alloyed steel grade M333 (420Mod), which has a lower carbon content, shows significantly higher toughness values. These can be further improved by lowering the austenitizing temperature. This behavior correlates well with the reduced tendency to form proeutectoid carbides at grain boundaries. A similar correlation can be found for the steel grades AISI 440B and the nitrogen-alloyed M340 (440Mod).
Volume 4D, Heat Treating of Irons and Steels ⇒ Tool Steels ⇒ Heat Treating of Mold Steels and Corrosion-Resistant Tool Steels ⇒ Recommended Heat Treating Practices
The graph shows the effects of different cooling rates on the toughness properties (un-notched samples) of AISI 420 and nitrogen-alloyed M333 tool steels.
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Heat treat 2015 finishes with a “bang!”
November 2, 2015
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The ASM Heat Treating Society Conference and Exposition (Heat Treat 2015) took place in late October in Detroit. The three-day event, co-located with the American Gear Manufacturer's Association Gear Expo, attracted over 7000 heat treating and gear professionals from all over the world, including an equipment exhibition featuring 202 companies in 288 booths. The show featured top-notch technical programming as well as several new initiatives such as live equipment demonstrations on the show floor and a "hot" new social event that lit up the Detroit sky as well as local social media.
The technical program at Heat Treat featured more than 140 oral and poster presentations, including a new Applied Technology track focused on practical applications for operators. Jonn Nebbe, a metallurgical engineer at Eaton Corp., said, "Learning about the academic side of things is nice, but learning practical applications that you can take back to the shop floor? That's what I'm here for."
Attendees also enjoyed a plenary session from Dr. Alan Taub, chief technical officer of the newly established American Lightweight Materials Manufacturing Innovation Institute, who discussed the LIFT (Lightweight Innovations for Tomorrow) consortium. The conference program also featured an expert-led panel on "New Development and Opportunities in Heat Treating" focused on technology needs and new disruptive technology within the industry. Finally, the popular Master Series lectures educated attendees on specific technical subjects such as the past and future of martensitic steels, bainite transformation in steel, and the Holloman-Jaffe parameter.
Local high school students got to participate in the ASM Materials Education Foundation "Mini Materials Camp" on the show floor during Heat Treat. Eight presenters gave hands-on science demonstrations to over 150 students in the mini-camp, including heat treating bobby pins and paper clips and the principle of diffusion at work in brassing a penny. College students also took part in the free "This is Heat Treat" student program, which included a special 35 and Under Keynote Breakfast and a student networking mixer on the show floor.
On the networking side of the event, attendees had many opportunities throughout the week to meet and catch up with old friends. Exhibitors and attendees were treated to a networking reception on Tuesday evening featuring local brews and appetizers on the show floor, and several refreshment and dessert breaks throughout the week. The main event however, the first-ever Heat Treat social event called "The Heat Is On," was held Wednesday evening at Waterview Loft at Port Detroit. Guests were treated to flame twirlers, local craft beer, and Detroit-style food. The evening was capped off by a fireworks display on the Detroit River, which surprised both guests and locals who happened to catch the show. The "mystery" fireworks caused quite a stir on social media and the news.
Attendees, exhibitors, and sponsors were positive about the direction that Heat Treat is going. "There is a new energy to this event," says Stephen Kowalski, president of the ASM Heat Treating Society and president, Kowalski Heat Treating. "The organizers are doing some exciting things with the programming, and the social event really was above and beyond all expectations and certainly had the local and international media on fire. Even if you have been to Heat Treat before, come again in 2017 – you won't be disappointed."
Chuck Faulkner, Market Development Manager, Heat Treatment & Metal Forming at Houghton International, says that Heat Treat is the must-attend event for the heat treating industry. "This show is one our company doesn't miss. We will be back in 2017."
Heat Treat 2017 will take place in Columbus, Ohio, on October 24-26, 2017. Space is limited and is expected to sell out. To reserve exhibit space, contact Christina Sandoval, global exhibition manager a [email protected] or 440.338.5151 ext. 5625.
The ASM Heat Treating Society Conference and Exposition (Heat Treat 2015) took place in late October in Detroit. The three-day event, co-located with the American Gear Manufacturer’s Association Gear Expo, attracted over 7000 heat treating and gear professionals from all over the world, including an equipment exhibition featuring 202 companies in 288 booths.
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