In a comparative studyL-6 of the spot weld fatigue strength of various steels grades, some of which included grades such as 1.33-mm Fully Stabilized (FS) 300/420 (HDGA), 1.35-mm DP 340/600 (HDGA), 1.24-mm TRIP 340/600 (HDGA), and 1.41-mm TRIP 340/600 (HDGA), it was concluded that Base Metal (BM) microstructure/properties have relatively little influence on spot weld fatigue behavior (Figure 1). However, DP 340/600 and TRIP 340/600 steels have slightly better spot weld fatigue performance than conventional low-strength Aluminum-Killed Drawing Quality (AKDQ) steels. Further, it was found that the fatigue strength of spot welds is mainly controlled by design factors such as sheet thickness and weld diameter. Therefore, if down-gauging with HSS is considered, design changes should be considered necessary to maintain durability of spot-welded assemblies.

 

Figure 1: Tensile-shear spot weld fatigue endurance curves for various HSS (The data are normalized to account for differences in sheet thickness and weld size. Davidson’s data in the plot refer to historical data.L-6).

Figure 1: Tensile-shear spot weld fatigue endurance curves for various HSS
(The data are normalized to account for differences in sheet thickness and weld size. Davidson’s data in the plot refer to historical data.L-6).

 

Similar to mild steel, an increase in the number of welds in AHSS will increase the component fatigue strength (Figure 2). Multiple welds on AHSS will increase the fatigue strength more than mild steel.

 

Figure 2: Effect of increase in number of welds in mild steel and DP steel components.S-4

Figure 2: Effect of increase in number of welds in mild steel and DP steel components.S-4

 

Figure 3 is a representative best-fit curve based on numerous data points obtained from mild steel, DP steels with tensile strengths ranging from 500 to 980 MPa, and MS steel with a tensile strength of 1400 MPa. The curve indicates that the fatigue strength of single spot welds does not depend on the BM strength.

 

Figure 3: A best-fit curve through many data points for MS, DP steels, and MS steel (Fatigue strength of single spot welds does not depend on BM strength.L-2)

Figure 3: A best-fit curve through many data points for MS, DP steels, and MS steel (Fatigue strength of single spot welds does not depend on BM strength.L-2)

 

 

Related Posts
Filter by
Post Page
Joining Arc Welding RSW Joint Performance Testing homepage-featured-top main-blog Blog Resistance Welding Steel to Aluminium Laser Welding Tailored Products Press Hardened Steels Citations RSW Modelling and Performance
Sort by

Role of Coatings in the Formation of Defects in AHSS Welds

A common issue when welding Advanced High-Strength Steels (AHSS) is with protective coatings causing weld defects. A

18

Analyze Hydrogen Induced Cracking Susceptibility in Resistance Spot Welds

This articles summarizes a paper entitled, “New Test to Analyze Hydrogen Induced Cracking Susceptibility in

18

Benefits of Tailored Products in Automotive Body Construction

Key materials characteristics for formed parts include strength, thickness, and corrosion protection. Tailored

8

Process, Microstructure and Fracture Mode of Thick Stack-Ups of Aluminum Alloy to AHSS Dissimilar Spot Joints

This article summarizes a paper entitled, “Process, Microstructure and Fracture Mode of Thick Stack-Ups of

8

Improvement of Delayed Cracking in Laser Weld of AHSS and 980 3rd Gen AHSS

This article is a summary of the paper entitled, “IMPROVEMENT OF DELAYED CRACKING IN LASER WELD OF AHSS AND

8

GMAW of Dissimilar AHSS Sheets

This is a summary of a paper of the same title, authored by K. Májlinger, E. Kalácska, and P. Russo Spena, used by p

8

A-19

Citation: A-19.  M. A. Ahmad

8

RSW Failure Prediction

This article summarizes the findings of a paper entitled, “Prediction of Spot

8