A Comparative Study of Formability of Diode Laser Welds in DP980 and HSLA Steels

Abstract

Understanding effects of welding on strength and formability is critical to support wider application of advanced high strength steels in automotive components. In this study, High Strength Low Alloy (HSLA) and DP980 (Dual Phase, 980MPa) sheet steels were welded with a 4kW diode laser. Mechanical properties of welds and parent metals were assessed by tensile and limiting dome height tests, and related to microhardness distribution across the welds. The formability of HSLA welds was insensitive to the welding process and comparable to that of parent metal. For the DP steel, weld formability was much lower than that of corresponding parent metal, which appeared to be due to the formation of soft zones in the outer region of the Heat affected zone (HAZ) of the welds. It was found that increase of welding speed resulted in a slight increase of formability of the DP steel, associated with a reduction in the microhardness difference between base metal and HAZ soft zones.

Retraction: Microstructure and Properties of Fiber Laser Welded Joints of Ultrahigh-strength Steel 22MnB5 and its Dissimilar Combination with Q235 Steel

“…[3][4][5] Welding is a primary manufacturing process used in automobile industry, it is thus important to understand the mechanical and metallurgical phenomena concerned to the welding of AHSS. Furthermore, laser beam welding (LBW) has been very popular in auto manufacture, amounts of studies [6][7][8][9][10] have been carried out to investigate the laser welding of AHSS used in light weight vehicles. This technology possesses many advantages such as high welding speed, deep penetration, low heat input, narrow HAZ and effective integration with welding robots.…”

Microstructure and Mechanical Properties of Resistance Spot Welded Advanced High Strength Steels

“…The DP600 underwent interfacial fracture while the DP780 produced a full button. Xia et al 24) showed the effects of HAZ softening occurring for various DP alloys due to post-weld tempering. Higher grades of DP exhibit greater potential for HAZ softening due to larger volume fraction of martensite which experiences post-weld tempering.…”

Effects of Heat Input and Martensite on HAZ Softening in Laser Welding of Dual Phase Steels

“…4) Significant softening can also degrade the formability of welded blanks. 8) So far, no detailed or systematic study has been published to investigate the HAZ softening phenomenon of welded DP steels. Softening of DP steels by tempering using isothermal heat treatment has been investigated extensively.…”