Working with Boron Steel, AHSS – Automotive

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Over the past 25 years, OEM’s have been systematically replacing mild steel components with a variety of stronger, lighter and more exotic materials. In the early 70’s, vehicles were mostly made of mild steel but we are beginning to see the emergence of plastics as well as conventional High Strength Steels. ​The 2 primary reasons to the change in materials used in vehicle structures are fuel economy and safety. OEM’s are working very hard to squeeze more miles per gallon from their vehicles. In addition to better mileage, consumers are demanding and governments mandating safer vehicles. By combining mild steel to maximize impact absorption and High Strength Steels (HSS) to strengthen passenger cages, OEMs were able to achieve both objectives. This change has impacted and completely change the repair procedure for new vehicles today. All car owner have the right to know how their car is being repaired to ensure the safety features of a car is maintained after repair.

The term Boron Steel is often heard in automotive repair shops and it is something every technician fears the most. What is Boron? It’s an element in our world and is commonly used as an alloying element in developing advanced steels to achieve the 2 primary reasons mentioned above. Boron steel may be a dream material for vehicle makers, but to the collision industry it can be challenging. You can’t use traditional repair method on mild steel to repair vehicles with Boron steel as they behave differently. This is why:

  1. Do not straighten Boron steel
    • Boron steel cannot be straightened because of the extremely high heat used when it is being formed. When boron steel is damaged in a collision, work hardening makes it too brittle to be restored to its original state. Attempts to straighten a boron steel part will usually result in a cracked part. The use of heat may allow the part to be straightened without cracking but heat destroys the strength of the part. The only solution is to replace the part
  2. Cutting Boron Steel
    • Boron steel will remove the teeth on a reciprocating saw if it is used. It makes the work of a body technician miserable without the correct tools. A cutoff wheel or a plasma-arc torch is best recommended to cut boron steel, High Strength Steel (HSS) or Advanced High Strength Steel (AHSS). Plasma cutter is what every shops need today to ensure a quick and accurate cut possible for any repair. The good thing with Plasma cutter is that its not too expensive for any shop to invest. Why argue over a small investment while you can recover your money from efficiency and accurate repairs

      IMS Plasma Cutter 30FV

  3. Drilling Boron Steel
    • To replace damaged parts, spot welds joining these parts needs to be removed. Traditional ordinary drill bits can be used to remove spot welds on mild steel. Boron steel or any other HSS have much higher tensile strength, up to 1500MPa. Special drill bit or cutter must be used to remove spot welds on these materials. Some OEMs recommended the Tungsten Carbide 3-fluted bits (“Boron Killer“) to cut boron/HSS spot welds. This costly bits works fine but are made so hard and brittle that it cracks easily if dropped on the floor or not used properly. More over, it can’t be resharpened after it gets blunt, difficult for any small bodyshops to invest. A Japanese company BIC Tool Co., Ltd manufactures a special 2 flute type spot weld cutter that can be re-sharpened after it gets blunt. This has become many bodyshop’s alternative to the 3-fluted bits and its better as it saves the owner’s pocket as it can be resharpened with the S2000 Roken Grinder . Each time the SP802 is sharpened, it saves you the price of a new bit. Invest smart and increase work efficiency with the right tool.

      Spot weld cutter

      SP802 Spot Weld Cutter


  4. Welding Boron Steel
    • Boron steel can be easily welded. Resistance spot welding is typically preferred because there is minimal damage from heat effect as compared to the traditional MAG welding. Spot welding is normally recommended for repair at areas reachable by the welding pliers. MAG welding will then be used to join areas where the spotwelder pliers could not access. Lately, OEMs recommend MIG brazing for repairs on AHSS/Boron steel as the heat generated is much lower. Generally the steel sheets aren’t melted during brazing as silicon-bronze wire melts at a lower temperature than mild steel. However, due to the lower holding strength of MIG brazing, the size of the weld is made bigger and oval in shape to compensate the loss in strength.

 

Some spotweld removal bits cheaper alternatives, you can purchase below

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