Coming to Grips with Super Steels

Posted 6/11/2009
By Bob Chabot

The collision industry is under the gun. According to the American Iron and Steel Association, 60 percent of the steels used in manufacturing cars today did not exist 10 years ago. Automakers' use of new lightweight steel and steel alloys has grown quickly and is expected to accelerate over the next generation. For collision shops, this trend presents an enormous, dynamic challenge.

The Holy Grail: higher, lighter, lower

In the 1990s, mild steel (MS) accounted for nearly all of the steel used in vehicle manufacturing. MS offered adequate strength, yet enabled easier collision repair because of a more stable collision repair knowledge base and simpler repair procedures and skills. While MS continues to be the most common steel used in automobile manufacturing, experts say that new classes of steel now used for vehicle manufacturing are stronger, lighter and provide more flexibility to original equipment manufacturers (OEMs).

Further broadening the challenge for collision shops is the development and incorporation of next-generation steels, which use specific ingredients to achieve desired engineered attributes, and other lighter-weight metals, such as aluminum, titanium or magnesium; and non-metal composites, such as carbon fiber in vehicle components.

Looking forward, collision shops must adapt their repair knowledge, procedures and skills at an accelerating rate to keep pace with technological change. While some shops may find the task overwhelming, others will seize opportunity. Either way, understanding these new materials is key to a shop's survival.

Increasing consumer demand for improved safety, reduced noise, smoother ride, solid handling and infotainment features is a prime driver. In addition, regulatory initiatives for better crash-safety standards, improved fuel economy and lower CO2 emissions have also spurred the OEMs' move away from MS.

Life cycle assessment (LCA), a new metric that measures total greenhouse gas emissions from raw material production, vehicle manufacturing, use by consumers and end-of-life disposal, has effectively demonstrated that higher-strength steels have a lower LCA than MS, and in many cases aluminum, titanium and other metals. In addition, the advent of heavier, alternate propulsion systems has made the use of higher-strength steels a cost-effective, practical solution.

"Maximizing survivability is the driver in automobile design, not repairability," says Jeffrey Poole, a trainer with the Inter-Industry Conference on Auto Collision Repair (I-CAR). Automakers have improved passenger safety by constructing a protective shell around occupants that optimizes collision energy absorption through the engineered deformation of parts during an accident. By incorporating stronger steels in key areas, collision energy forces can be controlled and transferred away from occupants. For this reason, higher-strength steels are used in parts such as B pillars to avoid intrusion into the passenger compartment during side impacts and also in crossmembers and reinforcements surrounding fuel tanks.

According to the American Iron and Steel Institute, automakers intend to continue replacing mild steel with increasing amounts of higher strength steels - at least the next generation.

"Vehicle complexity has the potential to put us all out of business," Poole notes, and has fostered a number of wide-ranging issues. Those issues include multiple-steel assemblies, each possibly requiring a different procedure; determining whether to repair or replace; heat or cold straighten; restoring corrosion protection; laser and spot weld removal and more. Ongoing collaboration between the collision industry, steel producers, OEMs, trainers and regulators is needed to close the gaps between building vehicles that sell and then repairing them after an accident. Standardizing steel identification and including it in collision information, developing complete repair guidelines sooner, and discerning training needs and delivering continuing education are just some of the solutions.

Once an accident occurs, it is essential that a shop determine what is wrong through identification and accurate measurement. Shops also must research to discern which metals are present and the associated repair procedures and proper equipment required to return the vehicle to pre-crash condition. Then they must thoroughly document and present this information to both insurers and customers.

Traditional repair procedures often cannot be used, as they can damage or destroy the attributes and performance of new steels. Instead, radically different repair procedures specific to new steel types must be implemented. Access to repair information, especially for independent shops not associated with, or certified as a repairer by a specific automaker, can be another hurdle. Further_more, investments in more expensive, specialized equipment and acquiring new repair skills on a continual basis compound the challenge.

Just as mechanical service information has evolved, so too has collision repair. According to I-CAR, more vehicle makers are now providing specific repair technique recommendations for certain types and grades of steel and other newer materials. "OEMs have gradually evolved repair procedure policies because they don't want repairers re-engineering vehicles," Poole points out.

"The information is out there, but some of it isn't easy to get to," Poole adds. For the collision industry this requires shops to know as much about the types of metal as possible, as early in the repair process as possible. It is critical that shops first reference OEM-specific vehicle repair information and then include copies of the repair documentation in customer repair order files. Steel repair matrices and associated collision repair information and training can be sourced from I-CAR, individual automaker Web sites, NASTF.org and third-party providers.

While most information is available, there could be "time lag" - instances where new vehicles are sold and then involved in an accident before collision repair information and procedures are developed and posted on service information Web sites. "When no repair procedure exists for a part made with these new steels," Poole advises, "shops must err on the side of safety and choose replacement rather than repair." Ensuring the insurer and customer are aware of this before a repair is essential.

Insight Spotlight Bob Keith, senior director of education and training, CARSTAR Franchise Systems Inc., hosted a seminar at the recent ASA Annual Convention. Some of the insights he shared on a variety of new steel collision issues include: • Repair information - "We need to work with OEMs to get service information. I don't think repairers are aware of how much information is out there, where to find it and how to repair it." • New parts - "You can't assume all unibodies are the same anymore. Some repairers tend to fix things as they used to until something breaks. If you get a new body or see new parts in your shop that you haven't worked on before, take the time to identify and research before beginning repairs." • Equipment - "Shops must invest in specialized equipment and be adept at using more complex welders such as squeeze-type resistance welders that can cost up to $40,000, plasma cutters and specialized tungsten-carbide drills and drill bits." • Skills - "We must employ better repair planning. We need to be better researchers to find the correct repair information to ensure we're on the right repair track." • Training - "Independent collision repairers who aren't OEM-certified can find it more difficult to keep up. This makes continuing education more critical today. Solid training sources include I-CAR, OEM schools and third-party trainers."

Although higher-strength steel use in vehicle-unitized structures results in reduced passenger compartment deformation, frequently there are less-visible damage indicators after a collision. As steel strength is increased, it typically becomes harder, more brittle and more sensitive to heat. HSS is generally cold straightened, while AHSS/UHSS is typically not straightened at all. Cold straightening can also damage anchoring points and the lower strength steels attached to them. When mild steel is heated, it is generally strengthened. However, under that same heat, HSS is weakened and AHSS/UHSS can crack, break or be destroyed. Repairers should be aware that this makes the steel unable to absorb or deflect energy as originally designed for in the event of a collision. When such a vehicle is back on the road, collision energy is then transferred into the passenger compartment.

If heat has to be used and is allowed by the OEM, follow its recommended welding methods and techniques, such as stitch welds, to minimize the "heat affect zone" (HAZ), ensure safety, maintain warranties and avoid litigation. In many cases, OEMs now recommend complete part replacement rather than partial repair using heat.

Repair history impacts the future

The days of shortcuts and just repairing vehicles so they "look" right are over. "We as an industry need to know how to repair a vehicle and how to represent that repair to consumers, insurers and others," Poole notes. Keeping thorough and complete files for documentation purposes, as well as developing sound communication skills to convey concerns and needs to insurers and customers is no longer an option. Rather, it is a best practice and part of doing business today.

Crash investigation experts, for example, when surveying a vehicle damaged in an accident review the "prior loss history" of a vehicle. In particular, they review whether any prior repair was a contributing factor. Were incorrect repair techniques used that were cosmetic but undermined the vehicle's safety? Were there prior loss issues that were neglected and/or simply not addressed by the last repairer/ insurer? If a vehicle has had multiple collisions, which facility is responsible for improper repair?

"The answers to these questions in court can make for an interesting day at the office," Poole cautions. Failure to follow correct and ethical repair, and failing to document and communicate it can result in devastating liability claims, whether caused by a shop's negligence or ignorance.

Collision shops face challenges today that didn't exist just a few years ago. Staying current with new technology and products, identifying and implementing proper repair methods, acquiring and maintaining skill fluency, and documenting and presenting concerns all necessitate a commitment to detail. Clearly, the learning curve has gone vertical. The question is: Are you up to the climb?

(Sources: CARSTAR, I-CAR, American Iron and Steel Institute, World Auto Steel Association)

Bob Chabot is an automotive writer based in Bedford, Texas. He may be reached at robertjchabot@gmail.com.

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