One Minute Mentor: Hardness Depth Profiles of Stainless Steel after Nitriding and Nitrocarburizing
September 18, 2017
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X-ray diffraction analysis indicates that the hardened case consists of a mixture of expanded austenite and expanded martensite. Dissolving nitrogen into cubic martensite causes a tetragonal expansion leading to nitrogen-expanded martensite. In addition, E-carbonitride is present close to the surface. By comparing the hardness profiles in the graph, it can be concluded that nitrocarburizing generally leads to a thicker case than nitriding, and that a slightly higher maximum hardness is obtained after nitrocarburizing.
Martensitic stainless steels have been successfully nitrided and nitrocarburized. An example is given for molybdenum-stabilized AISI 420-type austenitic stainless steel 7C27Mo2.
The graph shows hardness-depth profiles after nitriding (solid lines) and nitrocarburizing (dash-dot lines) for 16 hours of 100 μm strip 7C27Mo2 (molybdenum-modified AISI 420) at the temperatures indicated. Hardness profiles were fitted assuming a sigmoidal function.
Volume 4D, Heat Treating of Irons and Steels ⇒ Heat Treated High-Alloy Steels ⇒ Low-Temperature Surface Hardening of Stainless Steel ⇒ Low-Temperature Nitriding and Nitrocarburizing of Other Stainless Steels
X-ray diffraction analysis indicates that the hardened case consists of a mixture of expanded austenite and expanded martensite.
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Nucor to build new steel bar micro mill in Midwest or Southeast
September 17, 2017
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Nucor Corp., Charlotte, N.C., announces that its board of directors has approved a steel bar micro mill project, and also announces that the company is considering five states in the Midwest and Southeast as a location for the project. The states being considered include Nebraska, Kansas, Missouri, South Carolina, and Florida. Nucor's board of directors also approved the expansion of its existing merchant bar operations in either Illinois or Ohio.
Nucor's bar mills are a cornerstone of the company; they have generated significant value in the past, and they are expected to generate significant value in the future. Both the micro mill project and the expansion of its merchant bar operations are part of Nucor's planned strategy for long-term profitable growth. By leveraging Nucor's existing operating abilities, these projects will maintain our position as a low-cost producer and will allow us to better serve our customers.
Nucor and its affiliates are manufacturers of steel products, with operating facilities primarily in the United Sstates and Canada. Products include carbon and alloy steel -- in bars, beams, sheet and plate; hollow structural section tubing; electrical conduit; steel piling; steel joists and joist girders; steel deck; fabricated concrete reinforcing steel; cold finished steel; steel fasteners; metal building systems; steel grating; and wire and wire mesh.
Through the David J. Joseph Company, Nucor also brokers ferrous and nonferrous metals, pig iron and HBI/DRI; supplies ferro-alloys; and processes ferrous and nonferrous scrap. Nucor is North America's largest recycler.
http://www.nucor.com
Nucor Corp., Charlotte, N.C., announces that its board of directors has approved a new steel bar micro mill project, and also announces that the company is considering five states in the Midwest and Southeast as a location for the project.
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3D optical profiler combines rotational module with high-res translation platform
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Sensofar Metrology, Barcelona, announces the Five Axis, a new addition to its high-end non-contact 3D surface metrology systems that combines a high-accuracy rotational module and a high-resolution translation platform, together with advanced inspection and analysis capabilities.
This enables automated 3D surface measurements at defined positions (perspectives) that combine to create full 3D volumetric measurements – ideal for micromachining, additive manufacturing, tooling, and medical technology applications.
The Five Axis also integrates several special acquisition modes designed to complement and exploit the capabilities of the motion system. Manual mode measures individual field-of-views (FOVs) with high-accuracy positioning, while Grid mode can capture individual FOVs at several different (lateral) positions.
Finally, 3D mode is an automated procedure using a ‘five multiple recipe' (5MR) that combines five-axis positions and measurement acquisition to obtain a 3D topography in the STL file format. The STL file format is supported by many 3D software analysis platforms, such as Gom, Polyworks, Kotem, and Geomagic.
Drawing on Sensofar's proprietary ‘3-in-1' sensor head technology approach, three available measurement technologies provide unequaled versatility across a broad range of scales and structures – focus variation for shape and form, interferometry for sub-nanometric roughness, and confocal for critical dimensions that require high lateral as well as vertical resolution. The Five Axis system is thus effectively a dedicated solution for comprehensive surface characterization of a sample from different perspectives and for different application needs, including full 3D acquisition.
With the acquisition controlled through Sensofar's intuitive, user-friendly SensoSCAN interface, an additional advanced analysis module provides the necessary tools for determining form deviation from 3D CAD models, for highlighting test and wear deviations (e.g. for tooling), for reverse engineering applications, as well as measuring critical dimensions (angles, radius, contour), surface texture according ISO 25178 (form and roughness) and volume.
www.sensofar.com
Sensofar Metrology, Barcelona, announces the Five Axis, a new addition to its non-contact 3D surface metrology systems that combines a high-accuracy rotational module and a high-resolution translation platform, together with advanced inspection and analysis capabilities.
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Materialise 3D-printed titanium maxillofacial implants cleared for U.S. market
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Materialise NV, Belgium, announces that its 3D-printed titanium for maxillofacial surgery has received clearance for the U.S. market, further extending Materialise's longstanding collaboration with DePuy Synthes, which will distribute the device in the United States. It is the first of the Materialise selection of implants to receive clearance for U.S. markets.
The Trumatch titanium 3D-printed implants are part of a personalized total solution for orthognathic surgery, also known as corrective jaw surgery, as well as for facial reconstruction. From virtual surgical planning to the 3D-printed implants used in combination with 3D-printed surgical guides, the system can help achieve better aesthetic results and minimize surgery time for patients. It has achieved positive results in European and Australian markets since its introduction in 2016.
These are the first 3D-printed titanium maxillofacial implants to receive clearance for the U.S. market, making 3D printing technology more accessible for the U.S. healthcare industry. The solution relies on the Materialise backbone of services, tapping into their software development, clinical engineering, and 3D printing production facilities.
"The decision is a real milestone for our medical department," says Brigitte de Vet, Vice President of Materialise Medical. "Thanks to our partnership with DePuy Synthes, our devices will be able to provide better healthcare for as many patients as possible."
According to Dr. Thomas Schouman, CMF surgeon at Groupe Hospitalier Pitié Salpêtrière, France, "For seven years now I've experienced the benefits of 3D-printed implants firsthand – they simplify maxillofacial surgery and allow me to perform procedures more accurately, saving time in the OR and improving patient outcomes. Moreover, they offer new treatment possibilities, allowing me to perform more complex surgeries or multiple procedures in a single intervention, whereas without the implants, several interventions would be necessary."
www.materialise.com
Materialise NV, Belgium, announces that its 3D-printed titanium for maxillofacial surgery has received clearance for the U.S. market, further extending Materialise’s longstanding collaboration with DePuy Synthes, which will distribute the device in the United States.
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Outokumpu Supra 316plus stainless steel reduces weight of LNG tank container by 30%
September 13, 2017
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Outokumpu Oy, Finland, announces that Finnish liquefied natural gas tank manufacturer LNGTainer has launched a new tank that brings together two innovations – LNGTainer's game-changing tank container, and Outokumpu's unique austenitic stainless steel grade, Supra 316plus (EN 1.4420, UNS S31655).
"The most revolutionary aspect of LNGTainer's new tank container is that the structure includes a lightweight, flexible inside tank, and an outside pressure vessel," says LGTainer CEO Tom Sommardal. "For the lightweight inside tank, we chose Outokumpu's Supra 316plus steel grade. With the new patented structure, we could decrease the weight of the tank by 30% and increase its capacity by 15%. Because the weight of the inside tank is significantly less than in competing tanks, the time for cooling off the inside tank is considerably shorter. The lightweight inside tank cools off faster for transport."
LNGTainer first considered aluminum for the inside tank, while Outokumpu offered Supra 316plus because of its properties. Supra 316plus has relatively better low-temperature properties compared to other similar materials. In fact, its strength and ductility only improve as the temperature drops down to the lowest measured cryogenic temperature of −196°Celsius. LNG is transported at a temperature of −164°C, and then is warmed back to gas when delivered.
"By having excellent low temperature properties, Supra 316plus enables thinner gauges, which translates as savings in weight, fuel, and energy costs, as well as a lower carbon footprint. LNGTainer's new tank container is a real breakthrough, and it demonstrates the best use of stainless steel properties in extreme conditions," says Product Manager Juha Kela at Outokumpu.
Supra 316plus has a higher chromium and nitrogen content, and less nickel and molybdenum. Thanks to the optimized composition, the grade has good corrosion resistance and its performance is superior to conventional steel grades when the temperature drops down to cryogenic temperatures. In addition, the price of the grade is competitive and stable.
www.outokumpu.com/stainless-news
Outokumpu Oy, Finland, announces that Finnish liquefied natural gas tank manufacturer LNGTainer has launched a new tank that brings together two innovations – LNGTainer’s game-changing tank container, and Outokumpu’s unique austenitic stainless steel grade, Supra 316plus (EN 1.4420, UNS S31655).
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Aspects of Precise Heat Input Control for High Frequency Welding
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High-frequency welding is a thermo-mechanical process that relies on precise heat input as well as mechanical control as strip edges are heated and forged together to produce a seam weld. Heat input can be defined as a way of characterizing the temperature distribution at the strip edges prior to forging them together. Heat input is affected by several process variables, ranging from raw material properties to welder settings and weld area setup.
These are summarized in this paper, with special attention to the effects of welder frequency, welder power, line speed, and steel alloy composition on heat input and the resulting weld quality. Frequencies in the range of 100 - 800 kHz are considered. Data from tube mills (including general data and controlled on-the-mill experiments), laboratory evaluation, and gleeble simulations are included in this paper.
Dr. Lesley D. Frame , Thermatool Corp., East Haven, CT
Mr. Kevin Davis , Thermatool Corp., East Haven, CT
Ms. Olexandra Tupalo , Thermatool Corp., East Haven, CT
Mr. Tom Ignatowski , Thermatool Corp., East Haven, CT
Mr. Mick Nallen , Thermatool Corp., East Haven, CT
Tuesday, October 24, 2017: 11:20 AM
A223-225 (Greater Columbus Convention Center)
https://asm.confex.com/asm/ht2017/webprogram/Paper43683.html
High-frequency welding is a thermo-mechanical process that relies on precise heat input as well as mechanical control as strip edges are heated and forged together to produce a seam weld.
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Lindberg MPH stackable box furnaces heat treat maritime equipment
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Lindberg MPH, Riverside, Mich., has shipped a Temperite box furnace and a Treet-All box furnace to a manufacturer of maritime equipment. The box furnaces are designed to be used in a stacked configuration or stand alone. They can also be used with a roller quench tank if needed. The box furnaces have work chamber dimensions of 12 x 30x12 inches. " H.
The Temperite and Treet-All are a modular, stackable, and space-saving line of box furnaces that meets and exceeds industry standards for heat-up rates and outer shell temperatures. The over/under box furnaces can be bench-mounted, stacked, or supplied with a furnace stand and quench thank. The optional split quench tank, mounted on wheels, is designed for use with water and oil. Removable work baskets are also included.
The Temperite Box Furnace has a high velocity forced convection heating system and three loading levels with two removable shelves. The work area temperature uniformity is ±1ten inches over the range of 600 to 1400°F. An empty furnace would take approximately 1.5 hours to heat up from ambient to maximum temperature.
The Treet All box furnace has a work area temperature uniformity of ±25°F over the range of 1400 to 2000°F. The furnace is equipped with nitrogen atmosphere capability with retort system.
"The stackable design minimizes floor space and allows for more efficient use of the customer's work space,"- says Kelley Shreve, Applications Engineer.
www.lindbergmph.com
Lindberg MPH, Riverside, Mich., has shipped a Temperite box furnace and a Treet-All box furnace to a manufacturer of maritime equipment.
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Single-crystal shape memory CuAlMn bar produced by unique heat treating process
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Tohoku University, Japan, reports that its researchers and colleagues have found an economical way to improve the properties of copper-aluminum-manganese 'shape memory' alloys by a unique heat treating method. The method could make way for the mass production of these improved metals for a variety of applications, including earthquake-resistant construction materials.
The alloy is made of copper, aluminum, and manganese, and is a well-known shape memory metal that is easy to cut with machines. Increasing the size of the material's crystals drastically enhances its elasticity. Altering its shape also makes it quite strong. These combined features make it very attractive for building structures that can withstand earthquakes.
Most metals are made of a large number of crystals but, in some cases, their properties improve when they are formed of a single crystal. However, single-crystal metals are expensive to produce. Metallurgists have developed a cheaper production method that takes advantage of a phenomenon known as 'abnormal grain growth.' This process causes the metal's multiple 'grains', or crystals, to grow irregularly, some at the expense of others, when it is exposed to heat.
The team's technique involves several cycles of heating and cooling that result in a single-crystal metal bar 70 cm in length and 15 mm in diameter. According to Toshihiro Omori, the lead researcher in the study, this is very large compared to the sizes of current shape memory alloy bars, making it suitable for building and civil engineering applications.
To produce the large single-crystal bar, the alloy is heated to 900°C, then cooled to 500°C, five times. This is followed by four cycles of heating to 740°C then cooling to 500°C. Finally, the metal is heated one last time to 900°C. Omitting the lower temperature heating (740°C)/cooling (500°C) cycles does not lead to the single-crystal result.
"Since the present technique is advantageous for mass production of single crystals because of the simplicity of the process, this finding opens the way for applications of shape memory single crystals for structural materials, such as for seismic applications in buildings and bridges," conclude the researchers in their study published in the journal Nature Communications.
http://www.tohoku.ac.jp/en/press/improving_earthquake_resistance.html
Tohoku University, Japan, reports that its researchers and colleagues have found an economical way to improve the properties of copper-aluminum-manganese ‘shape memory’ alloys by a unique heat treating method.
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What you need to know about heat treating
September 11, 2017
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Engineered components – from bearings to turbine blades and everything in between – acquire much of their value and application readiness during controlled heating and cooling cycles, otherwise known as heat treating. Though practiced for millennia, the process of heat treating has only, in the last century or so, given up its secrets, making it possible for manufacturers to consistently produce steel and nonferrous metal parts with specific properties and predictable lifetime and performance ranges.
Heat treating leverages the familiar process-structure-property-performance relationship on which modern materials science is based. As metals and alloys are heated and cooled they undergo a series of structural transformations accompanied by the redistribution of constituent elements, phases, and defects. Over the past several decades, industry, academia, and government agencies have invested a significant amount of time, energy, and resources to better understand these changes and how they impact the property and performance parameters of the steels and alloys on which our economy, security, and welfare depend.
With each new discovery, the heat treating process becomes more repeatable and systematic, raising the bar for every participant in the industrial supply chain. To remain competitive, suppliers of all sizes must periodically evaluate and, if necessary, upgrade their heat treating practices. What this entails and how to do it confidently will be conveyed in an instructor-led course called "Practical Heat Treating" that will be held September 25-28 on the ASM International campus in Materials Park, Ohio. The intense four-day course, delivered from a predominantly how-to perspective, will cover the most common heat treat processes and explain how to adapt them for specific materials and properties of interest.
By the end of the course, led by instructor William L. Mankins, FASM, students will be equipped to set up and run any process for standard steels as well as aluminum, copper, magnesium, and nickel alloys. They will also know how to set realistic production goals and track those using standard QC procedures. And when problems arise, they will know how to determine the cause. In most cases, heat treating problems stem from multiple contributing factors. The course will bring many of these into view and offer insights on how to minimize their impact on finished goods.
Did You Know:
- Slow cooling can prevent or minimize distortion in tooling with many section size changes.
- The precipitation or dispersion of fine particles during age strengthening tends to bond constituent crystals together at their slip planes, making them more resistant to deformation.
- Hardness and ductility are opposing properties. The harder the material, the less ductile it tends to be, and vice versa.
- Quick quenches can help suppress undesired transformations, phases, and crystal structures, for example, producing hard martensitic steel.
- Alloys, such as bronze, whose constituents remain in solid solution down to room temperature and below, can only be hardened by cold working.
- Annealing causes grain growth and has a smoothing effect on grain boundaries, making metals and alloys more ductile and easier to form.
- Normalizing helps refine grain structure and can minimize residual stress, making precision parts easier to machine, weld, and assemble.
- Tempering relieves stresses that accumulate during the hardening process.
Engineered components – from bearings to turbine blades and everything in between – acquire much of their value and application readiness during controlled heating and cooling cycles, otherwise known as heat treating. Though practiced for millennia, the process of heat treating has only, in the last century or so, given up its secrets, making it possible for manufacturers to consistently produce steel and nonferrous metal parts with specific properties and predictable lifetime and performance ranges.
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Spray Tips: Aspirating Volumetric Feeder
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The diagram illustrates an aspirating-type volumetric feeder, in which a continuous circumferential groove in a powder-feed wheel fills with powder by gravity. Powder is packed into the groove by a counter-rotating, inverted conical stirrer. The conical stirrer helps to maintain a more consistent powder bed density above the feed slots, ensuring uniform filling of powder in the groove.
Powder is picked up in an aspirating venture tube, through which the carrier gas flows, creating a vacuum that sucks the powder out of the wheel. The uniformity of volumetric feed for this type of feeder becomes a strong function of the packing efficiency and packing uniformity of the powder particles into the metering wheel.
The diagram illustrates an aspirating-type volumetric feeder, in which a continuous circumferential groove in a powder-feed wheel fills with powder by gravity.
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