Advanced High Strength Steel

If handled improperly, the structural integrity of damaged vehicles may be at risk

by Anne Koppel Conway

“In a nutshell the primary reason behind the use of advanced high strength steel (AHSS) is the reduction of fuel consumption – reducing our carbon footprint – and the safety of vehicle occupants,” said John Leddy, owner and managing member of LDC Consulting. The Seattle based company sells equipment and offers training related to working on high strength steels used in the auto industry.

In addition to wanting to improve the safety of a vehicle and reduce fuel consumption, automakers hope to reduce their manufacturing costs by using the special alloyed steel, he said. The newer steels allow manufacturers to use fewer pieces for parts, because fewer joints are needed to create a part with the new steel.

The use of advanced high-strength steel reduces a vehicle’s structural weight by as much as 25 percent, according to the American Iron and Steel Institute.

“But as the new steels are becoming thinner and stronger, they are becoming more brittle,” Leddy said.

The genesis of AHSS

“The story of how this all got started goes back to the mid-90s with the inception of the Ultra Lightweight Steel Auto Body (ULSAB).” To help auto manufacturers, thirty-five of the world’s steel producers jumped in to come up with a viable lightweight, structurally superior steel auto body that is also affordable.

“The biggest change in steels has taken place between 2007 and 2008.” As far as OEMs incorporating the AHSS into their vehicles, Leddy said, “Honda is moving faster than Toyota.”

Using AHSS does make a difference

The photo, taken from a YouTube video, shows a Hyundai Genesis with ample AHSS and a lot of bonding glue – giving it 260 linear feet of torsional rigidity. Torsion is the twisting of an object due to an applied torque (the tendency of a force to rotate an object about an axis). With torsional rigidity the part is less likely to twist and bend during an accident, making it safer. So, torsional rigidity is a good thing.

In contrast, some countries’ standards are not as advanced, said Leddy. The Chinese car in the photo, also from a YouTube video, crumpled in an undated crash test, he said. The manufacturer of this car may have, by now, updated the metals in its vehicles.

Back in the 1970s when the first fuel crisis hit, “Café standards, or Corporate Average Fuel Economy – regulated by the National Highway Traffic Safety Administration (NHTSA) and the Environmental Protection Agency – were introduced.” he said. That’s when the government started mandating that by such and such a date vehicles would have to get so many miles per gallon for a manufacturer’s fleet of passenger cars and light trucks (less than 8500 Gross Vehicle Weight Rating or GVWR) sold in the United States for any given model year.

“Camp Obama is on it,” Leddy said. President Barack Obama’s administration, along with the automotive industry, environmental activists and members of state governments, recently released new fuel economy standards for passenger cars and light trucks. Under the new rules, by 2016 passenger vehicles will have to meet an average 39 mpg, while light trucks will be required to get 30 mpg –saving 1.8 billion barrels of oil and raising the average fuel efficiency of a new car by 30 percent.

A vehicle’s fuel consumption and safety standards are rated with a 5-Star crash rating system, Leddy said. “Everybody wants the coveted 5-Star Crash rating” – like a 5-Star hotel rating.
BOR-ON auto body analyzer
Photo courtesy of JNE Safe Repair Equipment

Deer in the headlights

“If spot welders don’t know what kind of steel they are dealing with, they are like deer in the headlights,” he said. The first thing you have to do is identify the type of steel used.

“The fastest way to detect AHSS within a vehicle is to use a metal strength tester,” such as the BOR-ON steel analyzer produced by the Swedish company JNE - Safe Repair Equipment, which Leddy represents. The analyzer operates through a clamp that is fastened onto a vehicle’s flange. A click of the tester provides a digital measurement of the metal’s strength.

Some estimating programs and OEM (Original Equipment Manufacturer) websites also provide some information regarding steel type and location. “But the OEM sites do not always tell you where the high strength steels are located, because sometimes manufacturers want to keep their trade secrets . . . secret.”

Many OEMs recommend not using salvaged structural parts “Since there is a higher margin of error with AHSS, many OEMs have recently recommended that salvaged structural parts not be used in repairs.” There are several concerns regarding the use of salvaged parts.

• The part could be damaged.
• The removal of factory spot welds of the salvaged part would create a second weld cycle on the new vehicle, thus compromising the integrity of the AHSS.

“One of the biggest concerns in repairing AHSS is the use of heat. In the past, heat could be applied to mild and other forms of traditional high-strength steel to straighten vehicle frames and structures. These steels allowed more repair flexibility, since the repairer could use heat to stress-relieve the steel. Sectioning and splicing were also procedures that were very common and carried out on a daily basis.

Graph showing the different strength of the steels
Photo courtesy of JNE Safe Repair Equipment

Same techniques don’t work with AHSS

When heat is applied to AHSS, the material becomes weaker. This is why many collision centers are upgrading their equipment to tackle the latest advancements in AHSS.

Also, if you try to bend AHSS, it is likely to snap (shear).

“If you don’t follow OEM repair procedures, you are opening yourself up for product liability,” he said.

Spot welding

Leddy recommends using spot welds as much as possible, because with spot welds there will be less heat to affect a zone. “OEMs often recommend that portable squeeze type resistant spot welders (STRSW) be used on accessible AHSS in a vehicle. The benefit of STRSW is that they can create factory-type welds. It is very important that the collision repair center has welding equipment that can produce a correct weld. Most OEMs only recommend Mig Welding in areas that STRSW cannot access,” he said.

A lot of vehicles are being repaired improperly

Given the current economics of the country, “along with insurance companies crunching down on shops, there are a lot of vehicles being repaired improperly right now,” Leddy said.

Although he did not have any figures for the US, Leddy cited an EDKRA estimate that “in Germany there are currently about 600,000 improperly repaired and potentially dangerous vehicles on German roads.”

The reason: Advanced high strength steel may be in all of today’s vehicles. . . “But when I go to collision repair shops, most of them are unaware of [the new steels], because [many techs] look at a car and see a black car or a blue one and don’t see the indications of where the high strength steel is located.”

Shop dropped as DRP by insurer

“Recently, I met with an owner of a large collision repair facility who has a great reputation for quality repairs. On a particular repair job, he said he needed to replace (not repair) a frame rail that was AHSS. However, the insurance claims manager told him that if he tried to replace the rail rather than repair it, he would be removed from the DRP program.”

In spite of the threat, “the shop owner continued to follow safe repair guidelines for the customer.” As a result of continuing to do the right thing, he received notice that he was dropped as a DRP by the insurer.

“I would assume that the reason for being dropped from the DRP program is that the insurance claims manager lacked” the appropriate education to understand what the proper repair needed to be. “It is important that insurers train their managers and estimators on the proper techniques for repair” so that vehicles can safely return to the road.

Identifying AHSS in the repair process

If the AHSS is not handled properly the structural integrity of these damaged vehicles may be at risk.

A vehicle’s safety cage is basically like a racecar’s roll-cage built around the occupants to protect them.

“When a vehicle is in a collision . . . at the moment of impact, everything in the vehicle including the airbags is geared to deploy within milliseconds. So if this vehicle with AHSS had been repaired improperly, then chances are those airbags will never deploy properly in the next accident. That’s real scary.”

AHSS can be a touchy subject

Another consequence of using AHSS for our industry is that it is going to result in more cars being declared totaled [by insurance companies]. Primarily, the lower end cars. “You take an ’08 Toyota Scion X, a $20,000 car, like the one I drive; and, after an accident, it needs two new frame rails to repair it properly.” The cost of replacing the frame rails would exceed the value of the vehicle, so the car would be totaled.

“A lot of shop techs will take this metal [AHSS] and hammer on it to straighten it.” Big mistake.

The sections with AHSS have to be repaired properly; otherwise “people’s lives are in jeopardy.”

The key is that “high strength steel needs to be replaced not repaired. You can’t hammer out crumpled AHSS that has been in an accident. We’re talking about replacing the metal at the joint – you know, like bone to bone,” Leddy said.

“The industry will continue to see more AHSS in newer vehicles in conjunction with new adhesives and different types of foams. With continued education, we can have safe vehicles, safe occupants, and a unity between insurance companies and the repair facilities.”

Steel is just one part of the saga

The steel and the aluminum industries have been battling for supremacy in supplying strong, lightweight metals for the auto industry. “Both are claiming that with the use of their particular metals there will be less of a carbon footprint,” Leddy said. (But that’s another story.)

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On the cutting edge of how cars are repaired, John Leddy has been on a quest to educate insurance companies, consumers and body shops on what’s in cars today and what the people involved with them should know. Leddy has been in the collision repair industry for about 34 years. He began as a floor sweeper in a collision repair shop. Last year he traveled to Sweden to learn about metal testers. The website for LDC Consultants is: www.ldc-consultants.com/services.html. Leddy can also be reached at (253) 261-7683.

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© 2010 Oregonians for Safe Auto Repair