NDLI: Resistance Spot Welding (RSW) Process Optimization for Uncoated 2.0mm Dual Phase 780 to 2.0 mm Uncoated 2.0 mm Dual Phase 780 (DP780) Steel for Automotive Applications

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Koganti, Ramakrishna Angotti, Sergio Wexler, Arnon Donald, F. Maatz
Copyright Year	2008
Abstract	There has been a substantial increase in the use of advanced high strength steel in automotive structures in the last few years. The usage of these materials is projected to grow significantly in the next 5–10 years with new safety and fuel economy regulations. Advanced High Strength Steels (AHSS) are getting popular with superior mechanical properties and weight advantages compared to mild steel materials. These new materials have significant manufacturing challenges, particularly for welding and stamping. Proper understanding of the weldability of these materials is critical for successful application in future vehicle programs. Due to high strength nature of AHSS materials, higher weld forces and longer weld times are needed to weld AHSS materials. This work is in support of lightweight structures development and during the weld development phase various gages of coated and uncoated AHSS materials (DP780, DP980, TRIP780, Boron, Algoma 700B) were investigated. Both 2T and 3T stack-up conditions were investigated. Also, some combination of AHSS materials with High Strength Low Alloy (HSLA) and Bake Hardenable 210 (BH210) electro galvanized (EG) steels were also investigated. In this paper, weld lobe development for 2.0 mm DP780 bare to 2.0 mm DP780 bare 2T stack-up combination is discussed. Weld lobes were developed with Mid Frequency Direct Current (MFDC) equipment, ISO type B-20 tip, constant weld force of 6.36 kN (1430 lbf), hold time of 5 cycles and the weld times were varied 21, 24 and 27 cycles. Based on the tensile, cross-tension and nugget data, there were no correlations were observed between tensile load and button size and also between cross-tension and button size. Weld cross section data indicated heat affected zone (HAZ) at the weld nugget area and hardness drop of 17% was observed at the HAZ area. Irrespective of weld cycles, similar HAZ was observed close to the weld nugget. The weld lobes, mechanical properties (tensile shear and cross tension), cross-section examination, and microhardness of 2.0 mm DP780 bare to 2.0 mm DP780 bare weld 2T stack-up results are discussed.
Starting Page	283
Ending Page	290
Page Count	8
File Format	PDF
ISBN	9780791848654
DOI	10.1115/IMECE2008-68579
e-ISBN	9780791838402
Volume Number	Volume 4: Design and Manufacturing
Conference Proceedings	ASME 2008 International Mechanical Engineering Congress and Exposition
Language	English
Publisher Date	2008-10-31
Publisher Place	Boston, Massachusetts, USA
Access Restriction	Subscribed
Subject Keyword	Cycles Regulations Welding Gages Optimization Vehicles Boron Fuel efficiency Metal stamping Weight (mass) Tension Manufacturing Safety Corporate average fuel economy High strength steel Alloys Lightweight structures Mechanical properties Steel Microhardness Stress Heat Knudsen number Automotive industry Shear (mechanics)
Content Type	Text
Resource Type	Article

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