Strong, Safe, Light Steel

An interesting development in the world of steel, of particular interest vis-a-vis achieving required levels of safety while helping minimize vehicle weight, which is becoming increasingly important: ThyssenKrupp Umformtechnik GmbH is going to start production of B-pillars for a German compact car using a tailored tempering process developed by its parent company, ThyssenKrupp Steel.

An interesting development in the world of steel, of particular interest vis-a-vis achieving required levels of safety while helping minimize vehicle weight, which is becoming increasingly important: ThyssenKrupp Umformtechnik GmbH is going to start production of B-pillars for a German compact car using a tailored tempering process developed by its parent company, ThyssenKrupp Steel.

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Here's the significance: While conventional hot forming (taking manganese-boron steel, heating it to from 880 to 950 degrees C, forming it, then rapidly cooling it, thereby producing a part with a strength up to 1,500 MPa and 30% lighter than it would be if made with a more-conventional material) results in a part that is the same strength throughout, the tailored tempering process allows specific areas of the part to have greater yield strength or other differences as required.

So in the case of the B-pillar, it's lower third will yield more while the upper section remains strong for passenger protection.

This is being achieved by using a die that is heated differently in different areas so that cooling rates are varied along the part. So in an area where the blank cools more slowly, the steel hardens less. According to ThyssenKrupp, depending on the thickness of the blank, the transition area between the harder and softer zones can be as little as 15 mm, and the accuracy is reproducible.

Clearly an advantage in making safer cars without adding unnecessary mass.