In December 2017, SAE released an updated and much-needed version of AMS 6931. Before we dig into some major changes in AMS 6931D, let’s take a look at where AMS 6931C left off.
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AMS 6931 is a specification for titanium bar, forgings, and forging stock. AMS 6931 is specific to the 6AL-4V alloy.
AMS 6931C covered products up to 6” in diameter or least distance between parallel sides. However, it is commonly requested for products larger than 6” to be certified to AMS 6931. Since larger sizes were not specifically covered in the specification, AMS 6931C left it up to the purchaser and producer to determine what mechanical requirements could be satisfied for any products outside of the range identified in the specification. Usually manufacturers interpreted this as either (1) product manufactured in a size outside of the range of AMS 6931C would be manufactured to meet the properties of the largest size that is covered, or (2) since there are no specific requirements for products outside of the range of the specification, test results would be for information only, and not cause for rejection.
AMS 6931D recognizes that purchasers and end users are looking for assurances of what mechanical properties can be achieved in larger section sizes, by extending the coverage to 10” in diameter or least distance between parallel sides. Also, while AMS 6931C defined properties for products with a maximum cross-section of 48 square inches, AMS 6931D extends to 79 square inches. This allows titanium AMS 6931D products in this extended range to be certified without a “for information only” caveat; we now have firm requirements. For products larger than 10” diameter or least distance between parallel sides, and beyond a 79 square inch cross-section, the spec still does mandate the purchaser and producer to agree on the properties.
The new revision of AMS 6931 also brings about changes in reporting and identification of products. Now, when a product is purchased outside of the range of AMS 6931D, the report (or some type of certification) must include a statement certifying the material as “AMS 6931D(EXC)”, and list the exceptions to the specification. This requirement also applies when any technical requirement is waived. Additionally, the material must then be marked with “AMS 6931D(EXC)”.
Note: Performance Titanium Group is a raw material distributor. PTG does not provide engineering or metallurgical advice. Do not use this information to make engineering or metallurgical decisions. This information is subject to change, without notification. PTG is not liable for any damages related to the use of the information provided herein. The entire risk is assumed by you, the user.
This posting is not inclusive of all amendments to the specification. To catch up on all of the changes in AMS 6931D and determine how they affect your organization, be sure to purchase a copy at http://standards.sae.org/ams6931d/.
Essential parts of the main landing gear of the Boeing 777 family come from VSMPO-AVISMA in Russia
dpa/picture alliance via Getty ImagesThe terrible war in Ukraine and subsequent sanctions placed on many Russian organizations have raised questions about potential supply chain vulnerabilities. While Russia is mostly an exporter of resources like oil, gas, and metals, one market where it is a dominant player is for titanium and titanium forgings. Many people are waking up to the potential consequences of a longer-term stoppage in the flow of these critical materials.
Titanium and titanium alloys have unique properties: they are lightweight and have a very high ratio of strength to weight. Their density is typically around 60% that of steel. They withstand high temperatures, and have a high resistance to corrosion. These properties have caused the metal to be widely used in the aerospace industry, chemical processing vessels and piping, power plant components, desalination plants, and medical applications like implants and surgical devices. Titanium alloys are also used in sporting equipment like golf club heads, bicycles, and winter sports equipment like bobsled runners. Separately, titanium dioxide is the principal pigment in white paint, and it is also used in paper, plastics, and cosmetics.
Titanium alloy forgings are particularly important in aerostructures and engines. Two special characteristics of the metal make it particularly attractive for advanced composite aircraft like the Boeing 787 and Airbus A350XWB. The first is that it is less likely to cause galvanic corrosion when joined to carbon fiber reinforced plastic (CFRP) parts like body and wing panels or control surfaces. Galvanic corrosion occurs when two dissimilar metals are connected to each other and electrons can flow and cause the metals to corrode. The carbon fibers in CRFPs are electrically conductive, so attaching them to aluminum alloys makes both the metal and the composite vulnerable to deterioration. Titanium alloys are resistant to this. The second attractive property is that titanium thermal coefficients of expansion are very similar to CFRPs. This is important because airplanes go through big temperature changes over normal flight cycles. Titanium alloys account for approximately 15% of the Boeing 787 airframe by weight. In the Airbus A350XWB, it is about 14%, and is used in landing gear, pylons, attachments, door surrounds, frames, and other parts.
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Two ores, ilmenite and rutile, are the principal sources of titanium, with the former making up 90% of production. The first step is to convert the ore to titanium sponge. The U.S., Russia, Kazakhstan, Ukraine, Japan, and China all produce titanium sponge.
VSMPO-AVISMA Corporation is the largest titanium producer in the world. It is located in Verkhnyaya Salda, Russia, about 1,800 km east of Moscow and around 550 km from the border with Kazakhstan. It produces titanium sponge and converts it into ingots. These ingots are in turn converted to billets or slabs. The billets are made into a wide variety of shapes including tubes, disks, and rings, as well as forgings.
Forging is a manufacturing process that strengthens metals. It uses compressive forces to align the metal grain structure with the shape of the part. Usually this is done at precise high temperatures, depending on the type of metal being worked. Blacksmiths traditionally forge pieces by pounding heated metal on an anvil with a hammer. Large industrial parts are forged with huge presses that exert many tons of pressure, or squeeze the parts in compression dies. We long ago pointed out the loss of forging capacity in the U.S. for large metal parts as a critical deficiency.
SVERDLOVSK REGION, RUSSIA - Loading a forging stock into a furnace in a forging complex at ... [+] VSMPO-AVISMA Corporation, a subsidiary of Russia's Rostec State Corporation and the world's largest titanium producer, situated in the town of Verkhnyaya Salda 195km north of the city of Yekaterinburg. Donat Sorokin/TASS (Photo by Donat Sorokin\TASS via Getty Images)
Donat Sorokin/TASSTitanium alloys are difficult to forge; it is challenging to flow the metal in dies to obtain the desired shapes. Because titanium alloys are also difficult to machine, producers want to forge them into “near net” shapes, i.e., as close as possible to the finished shape to minimize the time and cost of machining. Aerospace forgings, particularly for engine parts, must be ultra-reliable, so the temperature and strain have to be carefully controlled during the process.
Boeing has a partnership with VSMPO, the Boeing-VSMPO Innovation Center, which was established in 2000. Boeing also established a joint venture, Ural Boeing Manufacturing, in 2009, on the site of the VSMPO factory. The JV opened a second site in 2018, specializing in the rough machining of titanium forgings for all of Boeing’s commercial programs including the 737 MAX, 787, and 777X.
VSMPO-AVISMA supplies titanium forgings for the Airbus A350XWB via the Spanish company Aernnova Aerospace. Aernnova builds the horizontal tail plane in Getafe and Illescas in Spain and ships it to Toulouse, France where the final assembly line is located. Aernnova supplies almost all other Airbus programs, as well as important components for Boeing’s 747-8, 787-9/10, and its Dreamlifter large cargo freighter programs.
In 2019, the U.S. imported 95% of the titanium it consumed. Iluka Resources closed its Old Hickory mine in Virginia in 2016. Allegheny Technologies idled its Rowley, Utah titanium sponge facility in 2016 because it could buy imported material for less than its domestic cost of production. And Timet, who operated the last domestic titanium sponge plant in Henderson, Nevada, went through a mass layoff in 2020. All of these operations faced cost pressures from foreign competition, as well as suffered through the aerospace manufacturing downturn that came with the pandemic. The terrible situation in Ukraine and Russia will put a lot of pressure on titanium supply chains, and Boeing warned about this in January. With all the grim news coming from that part of the world, this vulnerability hasn’t received widespread attention outside of the industry – yet.
In December 2017, SAE released an updated and much-needed version of AMS 6931. Before we dig into some major changes in AMS 6931D, let’s take a look at where AMS 6931C left off.
AMS 6931 is a specification for titanium bar, forgings, and forging stock. AMS 6931 is specific to the 6AL-4V alloy.
AMS 6931C covered products up to 6” in diameter or least distance between parallel sides. However, it is commonly requested for products larger than 6” to be certified to AMS 6931. Since larger sizes were not specifically covered in the specification, AMS 6931C left it up to the purchaser and producer to determine what mechanical requirements could be satisfied for any products outside of the range identified in the specification. Usually manufacturers interpreted this as either (1) product manufactured in a size outside of the range of AMS 6931C would be manufactured to meet the properties of the largest size that is covered, or (2) since there are no specific requirements for products outside of the range of the specification, test results would be for information only, and not cause for rejection.
AMS 6931D recognizes that purchasers and end users are looking for assurances of what mechanical properties can be achieved in larger section sizes, by extending the coverage to 10” in diameter or least distance between parallel sides. Also, while AMS 6931C defined properties for products with a maximum cross-section of 48 square inches, AMS 6931D extends to 79 square inches. This allows titanium AMS 6931D products in this extended range to be certified without a “for information only” caveat; we now have firm requirements. For products larger than 10” diameter or least distance between parallel sides, and beyond a 79 square inch cross-section, the spec still does mandate the purchaser and producer to agree on the properties.
The new revision of AMS 6931 also brings about changes in reporting and identification of products. Now, when a product is purchased outside of the range of AMS 6931D, the report (or some type of certification) must include a statement certifying the material as “AMS 6931D(EXC)”, and list the exceptions to the specification. This requirement also applies when any technical requirement is waived. Additionally, the material must then be marked with “AMS 6931D(EXC)”.
Note: Performance Titanium Group is a raw material distributor. PTG does not provide engineering or metallurgical advice. Do not use this information to make engineering or metallurgical decisions. This information is subject to change, without notification. PTG is not liable for any damages related to the use of the information provided herein. The entire risk is assumed by you, the user.
This posting is not inclusive of all amendments to the specification. To catch up on all of the changes in AMS 6931D and determine how they affect your organization, be sure to purchase a copy at http://standards.sae.org/ams6931d/.
Essential parts of the main landing gear of the Boeing 777 family come from VSMPO-AVISMA in Russia
dpa/picture alliance via Getty ImagesThe terrible war in Ukraine and subsequent sanctions placed on many Russian organizations have raised questions about potential supply chain vulnerabilities. While Russia is mostly an exporter of resources like oil, gas, and metals, one market where it is a dominant player is for titanium and titanium forgingstitanium forgings. Many people are waking up to the potential consequences of a longer-term stoppage in the flow of these critical materials.
Titanium and titanium alloys have unique properties: they are lightweight and have a very high ratio of strength to weight. Their density is typically around 60% that of steel. They withstand high temperatures, and have a high resistance to corrosion. These properties have caused the metal to be widely used in the aerospace industry, chemical processing vessels and piping, power plant components, desalination plants, and medical applications like implants and surgical devices. Titanium alloys are also used in sporting equipment like golf club heads, bicycles, and winter sports equipment like bobsled runners. Separately, titanium dioxide is the principal pigment in white paint, and it is also used in paper, plastics, and cosmetics.
Titanium alloy forgings are particularly important in aerostructures and engines. Two special characteristics of the metal make it particularly attractive for advanced composite aircraft like the Boeing 787 and Airbus A350XWB. The first is that it is less likely to cause galvanic corrosion when joined to carbon fiber reinforced plastic (CFRP) parts like body and wing panels or control surfaces. Galvanic corrosion occurs when two dissimilar metals are connected to each other and electrons can flow and cause the metals to corrode. The carbon fibers in CRFPs are electrically conductive, so attaching them to aluminum alloys makes both the metal and the composite vulnerable to deterioration. Titanium alloys are resistant to this. The second attractive property is that titanium thermal coefficients of expansion are very similar to CFRPs. This is important because airplanes go through big temperature changes over normal flight cycles. Titanium alloys account for approximately 15% of the Boeing 787 airframe by weight. In the Airbus A350XWB, it is about 14%, and is used in landing gear, pylons, attachments, door surrounds, frames, and other parts.
Two ores, ilmenite and rutile, are the principal sources of titanium, with the former making up 90% of production. The first step is to convert the ore to titanium sponge. The U.S., Russia, Kazakhstan, Ukraine, Japan, and China all produce titanium sponge.
VSMPO-AVISMA Corporation is the largest titanium producer in the world. It is located in Verkhnyaya Salda, Russia, about 1,800 km east of Moscow and around 550 km from the border with Kazakhstan. It produces titanium sponge and converts it into ingots. These ingots are in turn converted to billets or slabs. The billets are made into a wide variety of shapes including tubes, disks, and rings, as well as forgings.
Forging is a manufacturing process that strengthens metals. It uses compressive forces to align the metal grain structure with the shape of the part. Usually this is done at precise high temperatures, depending on the type of metal being worked. Blacksmiths traditionally forge pieces by pounding heated metal on an anvil with a hammer. Large industrial parts are forged with huge presses that exert many tons of pressure, or squeeze the parts in compression dies. We long ago pointed out the loss of forging capacity in the U.S. for large metal parts as a critical deficiency.
SVERDLOVSK REGION, RUSSIA - Loading a forging stock into a furnace in a forging complex at ... [+] VSMPO-AVISMA Corporation, a subsidiary of Russia's Rostec State Corporation and the world's largest titanium producer, situated in the town of Verkhnyaya Salda 195km north of the city of Yekaterinburg. Donat Sorokin/TASS (Photo by Donat Sorokin\TASS via Getty Images)
Donat Sorokin/TASSTitanium alloys are difficult to forge; it is challenging to flow the metal in dies to obtain the desired shapes. Because titanium alloys are also difficult to machine, producers want to forge them into “near net” shapes, i.e., as close as possible to the finished shape to minimize the time and cost of machining. Aerospace forgings, particularly for engine parts, must be ultra-reliable, so the temperature and strain have to be carefully controlled during the process.
Boeing has a partnership with VSMPO, the Boeing-VSMPO Innovation Center, which was established in 2000. Boeing also established a joint venture, Ural Boeing Manufacturing, in 2009, on the site of the VSMPO factory. The JV opened a second site in 2018, specializing in the rough machining of titanium forgings for all of Boeing’s commercial programs including the 737 MAX, 787, and 777X.
VSMPO-AVISMA supplies titanium forgings for the Airbus A350XWB via the Spanish company Aernnova Aerospace. Aernnova builds the horizontal tail plane in Getafe and Illescas in Spain and ships it to Toulouse, France where the final assembly line is located. Aernnova supplies almost all other Airbus programs, as well as important components for Boeing’s 747-8, 787-9/10, and its Dreamlifter large cargo freighter programs.
In 2019, the U.S. imported 95% of the titanium it consumed. Iluka Resources closed its Old Hickory mine in Virginia in 2016. Allegheny Technologies idled its Rowley, Utah titanium sponge facility in 2016 because it could buy imported material for less than its domestic cost of production. And Timet, who operated the last domestic titanium sponge plant in Henderson, Nevada, went through a mass layoff in 2020. All of these operations faced cost pressures from foreign competition, as well as suffered through the aerospace manufacturing downturn that came with the pandemic. The terrible situation in Ukraine and Russia will put a lot of pressure on titanium supply chains, and Boeing warned about this in January. With all the grim news coming from that part of the world, this vulnerability hasn’t received widespread attention outside of the industry – yet.