51����, the largest American-owned heat treater in the United States, is proud to support NASA’s Artemis II mission. Our expertise spans thermal processing of raw materials, nickel-based tubing, and critical aerospace components—playing a vital role in bringing next-generation space technology to life. At the core of some of these components is the 6Al–4V titanium Launch Abort System (LAS), one of the most complex safety systems ever engineered. The LAS aboard the Orion spacecraft functions as a rocket capable of outrunning another rocket in an emergency. In the event of a catastrophic launch anomaly, its manifold enables the abort motor to ignite and safely propel the crew module away from the rocket. Designed to endure extreme conditions with zero margin for error, the LAS represents the pinnacle of aerospace safety and performance. 51���� is honored to contribute to this mission-critical technology, providing the precision, reliability, and advanced thermal processing that space exploration demands.

The success of Artemis II is set to energize this month’s Space Symposium in Colorado Springs. Visit us at Booth 705 to discover how 51����’ advanced thermal processing solutions are helping shape the future of space exploration.

Space Symposium Information

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This past weekend, our 51���� team had a fantastic time participating in the Souderton Holiday Parade! With the help of our amazing employees and their families, we shared smiles, festive greetings, and lots of candy with our wonderful community.

We’re grateful to be part of such a joyful tradition and to celebrate the season together. Here’s to spreading holiday spirit, goodwill, and cheer all month long!

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The 7th Annual 51���� Sales & Marketing Summit took place this year near our Souderton, PA facility, bringing together sales managers from all six 51���� commercial heat-treating locations. The team collaborated on sales forecasts, shared updates on new processes and plant developments, and aligned on key strategies for the year ahead. Following the meeting, the group enjoyed a team-building outing at Topgolf.

No matter the region—North, South, East, or West—our mission remains the same: deliver exceptional customer service and provide meaningful value to every customer we serve. With over 200 years of combined experience in thermal processing and metalworking, our sales team is equipped to support your most demanding heat treating needs.

Reach out to any of our sales managers to discuss your next project.

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1. What are some of the first steps I should take before sending parts out for vacuum heat treating?

Before vacuum thermal processing, ensuring the parts are free of foreign object debris (FOD) is essential. This includes removing contaminants like manufacturing oils, coolants, and machining residue. It’s also important to communicate whether the coolant used was water-based or oil-based—this helps your heat treater select the most effective cleaning method.

Many vacuum heat treaters use solvent degreasers for oil-based coolants and hot water/soap-based rinses for water-based coolants. Providing this information up front helps determine how to best prepare your parts for heat treatment.

Bottom line: Failing to address FOD can result in spotting, discoloration, or worse—surface contamination.

2. You made sure the parts are clean; now, how about the vacuum furnace?

Much like a home oven, vacuum furnaces require periodic cleaning—referred to in our world as a “bake-out.” This process removes residual FOD or contaminants left from previous runs.

Typical bake-out temperatures:

• Austenitic (300-series) steel grids, fixtures, and baskets: ~2150°F
• Furnace-only bake-out: ~2300–2400°F

Reaching these temperatures ensures even entrapped moisture in graphite components is eliminated—crucial for maintaining a clean process environment.

3. Okay, so the parts are clean and the furnace is clean. Are we ready to run?

Almost! One final but critical step: check the furnace leak rate.

• For most steels, aim for 20 microns/hour or less
• For reactive metals (like titanium), 5 microns/hour or less is ideal

Remember, all vacuum furnaces leak to some degree—perfection doesn’t exist in commercial heat treating. But keeping leak rates low is key to producing bright, shiny, contamination-free parts.

4. Now for the easy part: the thermal cycle. Right?

Well… not quite!

If you’re using partial pressure gas or backfill gas (nitrogen, argon or helium), you must also monitor the dew point and oxygen content of the process gas. When treating alloys that oxidize easily—even small traces of water vapor or oxygen can cause surface issues.

While dew point measures moisture, it does not measure oxygen. Using oxygen sensors alongside dew point monitoring provides a more complete picture of gas purity, ensuring optimal conditions for clean, bright results.

Also, consider the vacuum level:

• For 300/400 series stainless steels or PH alloys, a vacuum in the 10⁻⁴ Torr range (graphite hot zone) is typically sufficient.
• For titanium or reactive alloys, you’ll need a 10⁻⁶ Torr vacuum, which usually requires an all-metal (molybdenum) hot zone.

While graphite furnaces are capable, all-molybdenum systems offer superior part cleanliness for highly reactive materials.

Lastly, ensure proper thermocoupling of the load. Use contact thermocouples directly in a part or in a heat sink that represents the maximum cross-section. Poor thermocoupling can lead to a false sense of temperature stability—you may think the load is cool, but when the door opens, parts could still be hot enough to oxidize instantly (turning blue).

5. I followed all your recommendations, and the parts are still discolored! Why?

Even with every precaution, discoloration can still occur—and it’s understandably frustrating. But it’s important to distinguish between:

• Discoloration, which is superficial and doesn’t impact performance
• Surface contamination, which is detrimental, as it alters the surface microstructure

To confirm the difference, consider sending a representative part to a metallography lab. These labs can characterize the near-surface condition, helping you determine next steps—ranging from simple Scotch-Brite cleaning, to a chemical or mechanical etch that removes a few thousandths of material.

And featured in Today’s Medical Developments Magazine:

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51���� recently welcomed 20 students from North Penn High School for an engaging and educational tour of our campus.

During their visit, students had the opportunity to explore real-world applications of materials and processes used across a variety of industries—from aerospace to medical to energy. They were introduced to the fascinating world of heat treating and advanced manufacturing, gaining insight into how cutting-edge technology is transforming centuries-old processes.

By stepping inside a live manufacturing environment, these future leaders experienced firsthand how innovation, precision, and science come together to shape the products we rely on every day.

We’re proud to support STEM education and spark curiosity in the next generation of engineers, technicians, and manufacturers!

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Recently, we had the privilege of hosting Dr. Navin Manjooran, President of ASM International, and Al Singmaster, Director of ASM Philadelphia Liberty Bell Chapter, for an exclusive tour of both 51���� and Solar Manufacturing.

During the visit, Dr. Manjooran presented both companies with a commemorative plaque, recognizing our invaluable support, dedication, and contributions throughout his presidency at ASM International. This honor highlights Solar’s ongoing commitment to advancing materials science, fostering innovation, and making a lasting impact on ASM’s Mission and Community.

We are grateful for this recognition and remain dedicated to driving progress in materials engineering, manufacturing, and beyond!

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January 13, 2025, Souderton, PA – 51���� in Souderton, PA, is currently commissioning two additional 2-bar vacuum furnaces, expanding its capabilities to meet increased demand in the aerospace, industrial gas turbine sectors, and for specialized hydride/de-hydride processing of Titanium, Tantalum, and Niobium. These vacuum furnaces, produced by Solar’s sister company, , feature large working hot zones (45” x 45” x 72”) and are rated for operations up to 2400°F with a precise temperature uniformity of ±10°F.

Mike Moyer, Solar’s Vice President of Sales, commented, “We’re thrilled to add these advanced furnaces to Solar Souderton’s lineup. Equipped with Solar Manufacturing’s latest control systems, they ensure efficient, safe operation—meeting our customers’ needs for competitive pricing and fast delivery. This installation reinforces our commitment to consistently high-quality service.”

For additional information, contact Mike Moyer, VP of Sales, 51���� at 215-721-1502 x1207, or mikem@solaratm.com.

Visit our aerospace heat treating page for additional information.

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December 9, 2024, Souderton, PA – This weekend, 51���� was thrilled to participate in the Souderton Holiday Parade! Our amazing team and their families shared smiles, holiday greetings, and plenty of candy with the community.

We love being part of such a joyous event and celebrating the season with all of you. Here’s to spreading goodwill and holiday spirit!

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1. What type of furnace do I need?

Atmosphere or air furnaces work well for bar, sheet, or plate materials that will have stock removed afterward. Finished machined components and additive manufactured builds should be done in a vacuum furnace. When choosing a furnace, you must know if the furnace can hold the proper temperature tolerance throughout the run. If parts need to comply with industry and aerospace specifications, the furnace must demonstrate it can maintain ±10°F in the furnace work zone envelope.

2. Can I combine varied sizes and thicknesses in the same run?

There’s no need to run two loads if all can be done in one. AMS2759/3, Table 4 will give you an idea of thickness overlaps. A well-spaced load, not densely packed, will always achieve the best results. I’ve personally heard of bars being aged in their received bundles, which predictably causes a wide range of hardness variations. This is a clear sign of over and under-aging conditions, with the inside not getting hot enough and the outside exposed to heat for too long.

3. Everything went well with the aging cycle, but the hardness levels are nonconforming.

We operate at risk when we only complete the age harden of PH alloys. We must assume the upstream solution treatment (typically done at the mill) was performed accurately. This includes making sure the PH grade is cooled to below a specific temperature before the age harden. I assume the furnace was loaded (not densely packed), calibrated, surveyed, and thermocoupled correctly. When diagnosing a problem like this, you must take a piece, solution treat, and age it. If the hardness falls within the specified requirement, improper solution treatment was the root cause.

4. My customer is asking for H900, which develops a 40-47 HRC. However, my customer wants 40-43 maximum HRC.

We’ve seen these types of requests for HRC ranges that have only one or two points. In many cases, you must explain what’s feasible. PH Stainless grades usually have wider hardness ranges because there’s variability in chemistry and/or the response to the age harden. Plus, many specifications don’t allow you to deviate on the initial age harden cycle. H900 requires 900 ±10°F for 1 hour +15 minutes -0 minutes. That’s it. That’s where you must start. From our experience, this cycle typically develops a 44-46 HRC, so now you’re anywhere from 1HRC to 2HRC over the maximum.

If hardness exceeds the maximum specified, you can re-age at the same temperature (recommended) or even go 10°F higher to reduce the hardness by a point or two. But re-aging may cause the hardness to fall below 40HRC, resulting in a re-solution anneal and starting all over again.

5. Will my finished parts distort? Is there any concern about size change or distortion in raw bar stock?

People use PH grades because they believe they don’t move dimensionally. Not true. They distort minimally when compared to other quench and tempered alloys. Major steel mills have literature with predictable size contraction based on the age harden or H COND. Distortion, however, is very unpredictable, especially for parts made from hardened bars. In these situations, AMS2759/11 also discusses stress relieving of PH alloys 100°F below the final age temperature. I’ve seen this minimize distortion and heard of less movement of the parts, especially in elevated temperature applications.

For more information: ��Vacuum Age Hardening

And featured in Aerospace Manufacturing and Design Magazine:

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1: When I send my 17-4PH parts out for vacuum age hardening they are returned with discoloration. Isn’t the purpose of vacuum heat treating to eliminate that?

It is not uncommon for 17-4PH and similar alloys (15-5PH, 13-8MO etc.) to exhibit some discoloration even after being processed in a vacuum furnace. 17-4PH is precipitation age hardened at a low temperature, between 900°F-1150°F, where even a relatively low residual of water vapor in the vacuum furnace may produce a slight Chromium oxide during the cycle. This is commonly called “heat tint”. Discoloration may also be caused by inadequate cleaning.

2: I have some 17-4PH parts with heat tint and my customer will not accept them as-is. What do I do?

Consider glass bead blasting if acceptable to your customer. If glass bead blasting is not acceptable, parts could potentially be solution treated and re-aged. The solution heat treatment temperature is 1900°F. When vacuum is used, this temperature is in the range of Chromium oxide reduction. It is recommended to utilize a partial pressure with Argon to prevent the vaporization of the copper that exists in 17-4PH (not a concern at age hardening temperatures). A challenge is 17-4PH must be cooled below 90°F after solution treatment (Ms finish) and this is generally not possible to achieve without removing the parts from the furnace, thereby reintroducing new water vapor between solution and age. There is a risk of size change or distortion from this process, and it should be avoided if possible.

3: What is the best way to reduce the risk of heat tint when vacuum age hardening 17-4PH?

The best way to avoid heat tint is to utilize an all-metal hot-zone vacuum furnace that will achieve a very low vacuum level, around 5×10^-6 Torr. In this case, the residual water vapor level will be so low heat tint should not be observed.

4: I currently only have access to a graphite-insulated vacuum furnace, what can I do to avoid heat tint during age hardening?

If the vacuum furnace hot-zone is graphite-insulated (the most common type of vacuum furnace), parts may be shielded with stainless steel or titanium foil. This is generally effective however it increases the total processing time (and cost) since parts are shielded from the energy in the furnace. Foil is not inexpensive and further increases cost. Foil is also a safety hazard; the edges are sharp and one wrong move can cause deep cuts to skin.

5: Is gas purity, dewpoint, and leak rate of the vacuum furnace a consideration in avoiding heat tint?

Yes! Process gas should have no more than about 10PPM of residual oxygen and a dewpoint below about -80°F. If the gas isn’t clean and dry, everything else will have been in vain. This is usually monitored at the point furthest from the supply to detect any leaks in the overall system. The vacuum furnace should also have a very low leak rate, normally about 10 microns per hour or less. At that rate, assuming the rise is linear (which it will not be, it slows down as the Delta P decreases) it would take nearly 9 years for the furnace to leak up to atmospheric pressure.

For more information: ��Vacuum Age Hardening

And featured in Today’s Medical Developments:

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