Not your father’s steel

July 28, 2015
The recent “Great Designs in Steel” (GDIS) seminar in Livonia, Mich., in May made it clear that the core material of choice for the manufacturers is still steel, but not always traditional steel. 

Aluminum! Aluminum! Aluminum!

Now that I have your attention, this article is not about aluminum. It is about steel, the material of choice for automotive manufacturers for more than 100 years. But it certainly isn’t the same steel that we repaired just a few short years ago. Today we have UHSS, AHSS, Boron, Martensitic, Bake Hardened, Dual Phase, Nano Steels and or some cocktail of alloys that no one has even named!

The recent “Great Designs in Steel” (GDIS) seminar in Livonia, Mich., in May made it clear that the core material of choice for the manufacturers is still steel. But not just mild steel —  advanced steels are the core of most new vehicle designs. Advanced steel content is increasing with each new design to as much as 60 percent to 70 percent.

2016 Nissan Maxima

Why these trends? We all know that a big driver is CO2 emission reductions mandating that the C.A.F.E. standard of 54.5 mpg be achieved by 2025. During GDIS, Abey Abraham of Ducker Worldwide said, “A curb weight reduction of 460 lbs. per vehicle is needed to meet the 2025 CO2 compliance levels. AHSS continues its growth trajectory with approximately 254 pounds per vehicle in 2014, surpassing our estimates in 2010 for 2014 by over 20 lbs. per vehicle (prior 2014 estimate was 232 lbs.).

Lighter bodies also allow for smaller more efficient engines with similar performance characteristics and higher fuel economy. Improved fuel economy is just one piece of the puzzle. The other incentive is safety — the new roof crush, side impact and offset crash test standards have also accelerated the use of advanced steels. These steels are capable of handling extreme collision energy, but it is thinner and lighter. Also, new crash energy designs Like Honda’s “ACE” allow for crash energy to be directed around the passenger compartment. There is also increasing use of steels in the 1000+ Mega Pascal (Mpg) range in tensile strength (a measure of crushability).

American Honda announced a breakthrough rear rail that is 1500 Mpg, yet has “softened areas” (780 Mpg) at the end, allowing the rail to crush in a “Z” shape to absorb energy.

At the steel seminar, many manufacturers displayed cut away bodies and had presentations on new designs along with how they used advanced steels to create lighter/safer vehicles. Here are some highlights:

2016 Nissan Maxima

·      8th generation/80 pound weight reduction

·      First use of  steels in the 1.2 Giga Pascal (GPa) in this model

·      Upper body is 45 percent advanced materials

·      Platform is 55 percent advanced materials

2015 Nissan Murano

  • 51 percent use of advanced materials including 1.2 GPa steel allowed for a 6 percent reduction in mass in a longer/wider vehicle.
  • Nissan is also using material removal (scallops, notches, holes) to reduce weight.
2015 Nissan Murano 2015 Nissan Murano

2015 Acura TLX

  • 52 percent advanced material usage, 35 percent of that 590 MPa
  • 1500 MPa hot stamped one piece front door ring (inner structure)
2015 Acura TLX 2015 Acura TLX

2015 Ford Edge

  • 66 percent advanced materials
  • Bake hardened outer body panels
  • Boron “B” pillar and rocker reinforcements and a Hydro-Formed Dual Phase 1000 MPa front roof rail

2015 GM Colorado/Canyon

  • 42 percent of lower cab structure is advanced materials with UHSS rocker inner reinforcements
  • 53 percent of upper cab structure is advanced materials with 26.5 percent of that material  being UHSS (rocker, roof rail, and “B” pillar reinforcements)
2015 GM Colorado/Canyon 2015 GM Colorado/Canyon

What does all of this mean to the average collision repair shop?

As the OEMs evolve, the collision repairer also needs to evolve. There has been tremendous press around aluminum vehicle construction. Repairers need to be prepared as we will see more aluminum content in tomorrow’s vehicles.  But don’t get caught up in the hype around any one material.  Ninety nine percent of what we are repairing today and for the foreseeable future will be some combination of advanced steels and other materials.

As we all know, the 2015 Ford F-150 body is almost 100 percent aluminum and Cadillac has announced the new CT-6 and its hybridized aluminum/steel unibody construction. However, not all OEMs are moving down the aluminum road. Other manufacturers are backing off as recently exhibited by Fiat/Chrysler’s announcement not to have an aluminum body on the 2017 Jeep Wrangler.

So this is what I think that our evolution looks like.

1.     Repairers need to have access to and use OEM information in the repair planning phase.  We need to know what grades of steels are in use, where they are located, what the repairability is, can the part be sectioned or is full replacement needed. If repairers wait to discover this during the repair, it is too late. To maintain cycle time goals, these repair/replace decisions need to be made during the Disassembly for Repair (DFR) process. We also need to identify adhesive/sealers/foams needed to make sure that they are replaced accordingly.

This data also needs to be made available to our technicians so that they have all the information needed to do a complete, safe and accurate repair.

2.     Pre-measuring at the DFR phase is also a necessity, with the load path designs that are in place today. The old visual standards on vehicle structure damage analysis are less likely to be as pronounced and may be missed. One example: front rails now being tied into rockers to disburse crash energy away from the passenger compartment. This energy disbursement can cause outward damage to the rocker panel after a hard front end hit. Only accurate measurements documenting this damage will validate the need for additional repairs and possible structural alignment.

3.     Welding skills and equipment have to be upgraded. Heat is the number one enemy of advanced steels and welding skills in the industry are sad at best. Our technician’s ability to weld today’s high-strength materials are severely lacking and has to be a focal point for the industry. Recent I-CAR analysis states that only 31 percent of the technicians in the industry have training and certifications in basic welding skills; 6 percent have aluminum training and certifications; and 2 percent have structural steel training and certification. This does not include squeeze-type resistance or MIG brazing (required by Honda/Acura for specific UHSS applications). If these statistics don’t scare you, they should! They certainly scare me!

Welder technology is also changing, and if you haven’t upgraded in the last few years, you may not have what is required to meet OEM specs. This also includes varying wire alloys that may be required to meet the tensile strengths of today’s steels. Here is an example of American Honda’s welder requirements for their ProFirst Certified program.

Pulse control MIG weld equipment

180 amp, 220 V with pulse control, used with silicon bronze wire (ERCuSi-A) and 100 percent argon gas for MIG brazing.

Silicon bronze wire for MIG brazing ERCuSi-A/CuSi-3 Silicon bronze wire required for MIG brazing. Must be used with pulse control MIG welder & 100 percent argon gas.

MAG Wire for 590 to 980 Mpa steel MAG welding wire required for welding 590-980 MPa steel parts. Wire must be ≥142 ksi (980 MPa) minimum tensile strength.

4.     Culture-We as leaders in our businesses have to create a different culture in our repair facilities. Do not support the “We have always done it this way so why change” or “We can repair anything.” Your shop culture has to be centered on getting all of the pertinent information needed to do a correct repair before you start the repair. You need to embrace learning…. not just training for training sake! We have to have a culture of continuous improvement and a strong need to gain knowledge.  Have to have the courage to turn away vehicles that we are not equipped to repair correctly (equipment or skills).

I want to leave you with a few challenges:

  • Train everyone in the shop who works on the vehicles, too many shops just train what is required to meet a program.
  • Have those who are trained share their knowledge with others.
  • Train and certify everyone in the shop who welds (not just what is required for a program).
  • Make sure that your repair planners and techs have access to and use OEM repair information in the planning and repair phases.
  • Create, install, and hold everyone accountable to an in-process quality control standard.

Advanced steels and advanced vehicle structures are here to stay. Keep ahead of the curve and make sure that every repair that goes out your door is of the highest quality and meets the safety standards that the OEMs built into the vehicle!

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