Ultra-high-strength steel isn’t your standard steel—special tools and great care is needed when working with this unique material.
The ultra-high-strength steel (UHSS) used in the 2014 IS and the new RC and NX is tougher than ever before, with tensile strength levels between 980 and 1,500 MPa. Technicians should take note—UHSS is becoming more common in Toyota, Lexus and Scion vehicles, and this steel is not repairable. As a general rule, the stronger the material is, the more heat sensitive it is to work with when welding and removing welds. When using tools like belt file sanders and spot weld drills, a one-size-fits-all approach to choosing which tools to use doesn’t work. Use of the wrong implement can potentially weaken or damage UHSS.
“Some tools and the method in which they are used may generate too much heat and can possibly weaken the joining metal on the vehicle,” says Joe DiDonato, Collision Training Administrator, Technical & Body Training Department, Toyota Motor Sales, U.S.A., Inc. “The idea is to be sensitive to the metal that is remaining on the vehicle, not the metal that you are discarding. Technicians should take care to be aware of the materials they are working on and choose the appropriate tools.”
Know Your Material
Technicians can follow a simple process to make sure they have the right tools for the job. The first step is to check the Technical Information System (TIS) for the vehicle-specific structural outline. The outline will identify any areas of the vehicle that contain HSS and UHSS.
If the vehicle you are working on contains UHSS, the next thing to take into consideration is whether you will be discarding the material you are working on when you are replacing the part. If you are discarding the material, then you do not need to worry about using destructive tools on it. If you are reusing the material you are working on, then you need to be more cautious about handling the joining part if it is made from UHSS.
The final step is to select the appropriate tool and make sure it’s used at the correct operating speed for the work you are carrying out. When selecting drill bits, ensure that they are of adequate size and rated to be used on the type of material you are drilling. For sanders and other tools, take into consideration any damage they may do to the part you are working on or surrounding material. It should be noted that a cut-off wheel should not be used to remove factory spot welds on panels connected to UHSS parts. This tool generates a lot of heat and can weaken adjacent UHSS metal.
“Ultra-high-strength steel is an amazing material,” says DiDonato.” “We’ll continue to see it used in more and more vehicles—that’s why it’s so important for technicians to learn how to work with it.”