Advanced High strength steels
General Motors-AISI AAC Advanced High Strength Steel Repairability Study
Phase I Final Report
Introduction
The introduction of Advanced High Strength Steels (AHSS) to light vehicle body structure applications poses a significant challenge to organizations involved in the repair of vehicle structures. AHSS are typically produced by nontraditional thermal cycles and contain microstructural components whose mechanical properties can be altered by exposure to elevated temperatures. This temperature sensitivity could alter the mechanical behavior of AHSS after exposure to elevated temperatures during repair welding or flame straightening and could seriously affect the structural performance of AHSS components after repair. This study, requested by General Motors ' Collision Repair Tech. Center, examined the mechanical behavior of two AHSS products, a 600 MPa tensile strength (TS) dual phase steel and a 1300 MPa TS
Martensitic steel, after exposure to typical repair arc welding and flame straightening temperature cycles and developed recommended practices for repairing components made of these materials.
This study is the first phase of and anticipated multi-phase effort to characterize AHSS and develop appropriate repair procedures for their various grades. Phase I objectives were to develop an appropriate method for characterizing the mechanical behavior of AHSS upon exposure to typical repair procedures and to develop recommendations for heat application during the repair of parts made from the dual phase and martensitic grades mentioned above.
These AHSS grades are being specified for near-term General Motors vehicle platform components and require immediate repair procedure development. Subsequent phases of this activity will develop repair procedures for other AHSS grades as prioritized by General Motors or other auto OEM AHSS component introductions.
Phase I was conducted by a team composed of General Motors, AISI, and AISI Automotive
Phase I Final Report
Introduction
The introduction of Advanced High Strength Steels (AHSS) to light vehicle body structure applications poses a significant challenge to organizations involved in the repair of vehicle structures. AHSS are typically produced by nontraditional thermal cycles and contain microstructural components whose mechanical properties can be altered by exposure to elevated temperatures. This temperature sensitivity could alter the mechanical behavior of AHSS after exposure to elevated temperatures during repair welding or flame straightening and could seriously affect the structural performance of AHSS components after repair. This study, requested by General Motors ' Collision Repair Tech. Center, examined the mechanical behavior of two AHSS products, a 600 MPa tensile strength (TS) dual phase steel and a 1300 MPa TS
Martensitic steel, after exposure to typical repair arc welding and flame straightening temperature cycles and developed recommended practices for repairing components made of these materials.
This study is the first phase of and anticipated multi-phase effort to characterize AHSS and develop appropriate repair procedures for their various grades. Phase I objectives were to develop an appropriate method for characterizing the mechanical behavior of AHSS upon exposure to typical repair procedures and to develop recommendations for heat application during the repair of parts made from the dual phase and martensitic grades mentioned above.
These AHSS grades are being specified for near-term General Motors vehicle platform components and require immediate repair procedure development. Subsequent phases of this activity will develop repair procedures for other AHSS grades as prioritized by General Motors or other auto OEM AHSS component introductions.
Phase I was conducted by a team composed of General Motors, AISI, and AISI Automotive
References: 1. E. G. Brewer, K. Malstrom, R. Stevenson, and H. D. Pursel, "Effect of Simulated Repair Heat Treatments on the Physical Properties of High Strength Steels," General Motors Corporation Research Report No. PH-1251, August 9, 1985. 2. R. Stevenson, E. G. Brewer, K. Malstrom, and H. D. Pursel, "Effect of Simulated Repair Heat Treatments on the Physical Properties of High Strength Steels," SAE Technnical Paper No. 910292, SAE, Warrendale, PA, 1991.