Static Tensile Strength of Gas Metal Arc Welded (GMAW) Joints of Uncoated Dual Phase 600 (DP600) Steels

Author(s):  
Ramakrishna Koganti ◽  
Sergio Angotti ◽  
Armando Joaquin ◽  
Cindy Ziang ◽  
Chris Karas

With the increasing demand for safety, energy saving and emission reduction, Advanced High Strength Steels (AHSS) have become very attractive steels for automobile makers. The usage of AHSS steels is projected to grow significantly in the next 5–10 years with new safety and fuel economy regulations. These new steels have significant manufacturing challenges, particularly for welding and stamping. Welding of AHSS remains one of the technical challenges in the successful application of AHSS in automobile structures due to Heat affected Zones (HAZ) at the weld joint. In this study Gas Metal Arc Welding (GMAW) of a lap joint configuration consisting of 1.5 mm uncoated DP600 to itself was investigated. The objective of the study was to understand the wire feed rate and torch speed influence on lap joint strength. A two factor, two level, full factorial design of experiment (DOE) was conducted to understand the wire feed and torch speed influence on tensile strength. In order to understand the curvature effect, center point was also considered in the experiment. Based on the statistical analysis, wire feed rate was the only significant factor on static tensile strength. Metallurgical properties of the lap joints were evaluated using optical microscopy. Significant hardness drop of 40% was observed at the HAZ.

Author(s):  
Ramakrishna Koganti ◽  
Adrian Elliott ◽  
Cindy Jiang

With the increasing demand for safety, energy saving and emission reduction, Advanced High Strength Steels (AHSS) have become very attractive steels for automobile makers. The usage of AHSS steels is projected to grow significantly in the next 5–10 years with new safety and fuel economy regulations. These new steels have significant manufacturing challenges, particularly for welding and stamping. Welding of AHSS remains one of the technical challenges in the successful application of AHSS in automobile structures due to heat-affected zone (HAZ) at the weld joint. In this study Gas Metal Arc Welding (GMAW) of a lap joint configuration consisting of 1.4 mm uncoated DP980 to itself was investigated. The objective of the study was to understand the wire feed rate and torch speed influence on lap joint tensile strength (static and fatigue). A two factor, two level, full factorial design of experiment (DOE) was conducted to understand the wire feed and torch speed influence on tensile and fatigue strength of the welded joints. In order to understand the curvature effect, a center point was also included in the experiment. Based on the statistical analysis, neither factor was significant on static tensile strength, however, a two way interaction between wire feed rate and torch speed was significant on static tensile strength. Metallurgical properties of the lap joints were evaluated using optical microscopy. A significant hardness drop of 40% was observed at the HAZ.


Author(s):  
Ramakrishna Koganti ◽  
Cindy Jiang ◽  
Chris Karas

With the increasing demand for safety, energy saving and emission reduction, Advanced High Strength Steels (AHSS) have become very attractive steels for automobile makers. The usage of AHSS steels is projected to grow significantly in the next 5–10 years with new safety and fuel economy regulations. These new steels have significant manufacturing challenges, particularly for welding and stamping. Welding of AHSS remains one of the technical challenges in the successful application of AHSS in automobile structures due to Heat affected Zones (HAZ) at the weld joint. In this study Gas Metal Arc Welding (GMAW) of a lap joint configuration consisting of 1.5 mm Electro Galvanized (EG) Transformation Induced Plasticity 780 (TRIP780) to itself was investigated. The objective of the study was to understand the wire feed rate and torch speed influence on lap joint strength. Design of Experiments (DOE) was conducted to understand the wire feed and torch speed influence on tensile strength. Based on the statistical analysis, wire feed rate and torch speed were significant factors on static tensile strength. Two way interaction effect between wire feed and torch speed was significant. Metallurgical properties of the lap joints were evaluated using optical microscopy. No significant drop in hardness at HAZ, however, significant hardening was observed at the base metal and weld fillet interface.


Author(s):  
Ramakrishna Koganti ◽  
Cindy Jiang ◽  
Chris Karas

With the increasing demand for safety, energy saving and emission reduction, Advanced High Strength Steels (AHSS) have become very attractive steels for automobile makers. The usage of AHSS steels is projected to grow significantly in the next 5–10 years with new safety and fuel economy regulations. These new steels have significant manufacturing challenges, particularly for welding and stamping. Welding of AHSS remains one of the technical challenges in the successful application of AHSS in automobile structures due to heat-affected zone (HAZ) at the weld joint. In this study Gas Metal Arc Welding (GMAW) of a lap joint configuration consisting of 1.5 mm uncoated DP780 to itself was investigated. The objective of the study was to understand the wire feed rate (WFR) and torch (or robot) speed (TS) influence on lap joint tensile strength (static and fatigue). A two factor, two level, full factorial design of experiment (DOE) was conducted to understand the wire feed and torch speed influence on tensile and fatigue strength of the welded joints. In order to understand the curvature effect, center point was also considered in the experiment. Based on the statistical analysis both factors are significant on static tensile strength and two way interaction between wire feed rate and torch speed was also significant on static tensile strength. Wire feed rate was the common significant factor on all three fatigue load conditions (1200 lbf, 1500 lbf and 1900 lbf). Metallurgical properties of the lap joints were evaluated using optical microscopy. Significant hardness drop of 25% was observed at the HAZ. To understand the influence of weld parameters and weld geometry on mechanical properties, correlation analysis was conducted among weld heat input parameters, weld geometry and mechanical properties (both static and fatigue loads).


Author(s):  
Ramakrishna Koganti ◽  
Adrian Elliott

With the increasing demand for safety, energy saving and emission reduction, Advanced High Strength Steels (AHSS) have become very attractive steels for automobile makers. The usage of AHSS steels is projected to grow significantly in the next 5–10 years with new safety and fuel economy regulations. These new steels have significant manufacturing challenges, particularly for welding and stamping. Welding of AHSS remains one of the technical challenges in the successful application of AHSS in automobile structures due to heat affected zones (HAZ) at the weld joint. In this study, Gas Metal Arc Welding (GMAW) of a lap joint configuration consisting of 2.0 mm uncoated boron steel and 1.0 mm Usibor® 1500 steel was investigated. The objective of the study was to understand the wire feed rate (WFR) and torch (or robot) travel speed (TTS) influence on lap joint tensile strength. Design of Experiments (DOE) methodology was used to understand the process parameter influence on the joint strength. Based on the statistical analysis, wire feed rate and torch travel speed were significant factors on static tensile strength. The interaction effect between wire feed rate and torch travel speed was not significant. Metallurgical properties of the lap joints were evaluated using optical microscopy. Significant drops in hardness at the HAZ were observed on both Usibor® 1500 P and boron steels.


2018 ◽  
Vol 204 ◽  
pp. 06010
Author(s):  
Taufik Hardiansyah ◽  
Moch Rofi Imron ◽  
Johan Handoko ◽  
Solichin ◽  
Abdul Qolik

The purpose of this study was to find out the tensile strength of GMAW welded carbon steel with electric current variation and wire feed rate. The research method used was experimental research with electric current variation of 120 A, 140 A, and 160 A and variation of wire feed rate 4 m/min and 5 m/min. The tensile strength test of sample was done by ASTM E8 / E8M-09 test standard. The result showed that the electric current variation and wire feed rate in welding of carbon steel with GMAW welding gave effect on the value of tensile strength which was varied. The electric current of 120 A and the wire feed rate of 4 m/min obtained the highest tensile strength of 52.67 kgf/mm2 and welding with electric current of 120 A and wire feed rate of 5 m/min obtained the lowest tensile strength of 48.33 kgf/mm2.


Alloy Digest ◽  
2010 ◽  
Vol 59 (12) ◽  

Abstract Dogal 600 and 800 DP are high-strength steels with a microstructure that contains ferrite, which is soft and formable, and martensite, which is hard and contributes to the strength of the steel. The designation relates to the lowest tensile strength. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on forming, joining, and surface treatment. Filing Code: CS-160. Producer or source: SSAB Swedish Steel Inc. and SSAB Swedish Steel.


2012 ◽  
Vol 706-709 ◽  
pp. 2734-2739 ◽  
Author(s):  
Hana Jirková ◽  
Ludmila Kučerová ◽  
Bohuslav Mašek

The use of the combined influence of retained austenite and bainitic ferrite to improve strength and ductility has been known for many years from the treatment of multiphase steels. Recently, the very fine films of retained austenite along the martensitic laths have also become the centre of attention. This treatment is called the Q-P process (quenching and partitioning). In this experimental program the quenching temperature and the isothermal holding temperature for diffusion carbon distribution for three advanced high strength steels with carbon content of 0.43 % was examined. The alloying strategies have a different content of manganese and silicon, which leads to various martensite start and finish temperatures. The model treatment was carried out using a thermomechanical simulator. Tested regimes resulted in a tensile strength of over 2000MPa with a ductility of above 14 %. The increase of the partitioning temperature influenced the intensity of martensite tempering and caused the decrease of tensile strength by 400MPa down to 1600MPa and at the same time more than 10 % growth of ductility occurred, increasing it to more than 20%.


Author(s):  
Jouko A. Heikkala ◽  
Anu J. Väisänen

New ultra high strength (UHS) steels have been developed in order to get advantages in machine design and construction. Following benefits can be obtained for example: - less material usage due to lighter constructions; - better payload and less fuel consumption in vehicle industry; - energy saving in material production. A rough distinction of structural steels can be defined to ductile steels, with tensile strength less than 300 MPa, and high strength steels, up to 700 Mpa. A steel material can be defined as UHS steel when the tensile strength exceeds 700 MPa. Steels with yield strength of 1500 Mpa have been developed so far. UHS steels can also be divided into structural steels and wear resistant steels. With the tensile strength also the hardness increases and the tensile strain decreases. That causes several difficulties when the material is processed into products. Especially mechanical processing like bending, machining and shearing gets difficult as the material strength increases. That causes problems for the construction material users to find the proper manufacturing methods in production. In Oulu University Production Technology Laboratory material processing tests have been performed during several years in co-operation with the local steel manufacturer. The usability tests comprise mainly of bending and machining tests. Shearing and welding tests have been made to a smaller extent. Also laser treatment has been used for local heat conditioning in order to improve the bending and shearing properties, but these techniques are not yet widely used in production. The bending tests are carried out with standard bending tools and test steel plates with standard dimensions. The plate thickness varies depending on the test material. The target is to determine the reliable minimum bending radiuses whereby the plate can be bent without failure, from both sides and along the rolling direction and orthogonally to that. Also the springback angle is measured and the bent surfaces are evaluated according to several criteria. When necessary, also the mechanical testing of the formed material is carried out. The machining tests are made mainly by drilling. Also some milling tests have been performed. Drilling is a convenient way of machining testing because a substantial amount of holes can be drilled in one test plate. The drilling power can be observed precisely by monitoring the spindle power. Also a variety of different tool types can be used, from uncoated HSS drills to boring tools with indexable inserts. The optimal machining parameters (feed and speed) will be defined according to maximum tool life and minimum machining costs.


2015 ◽  
Vol 764-765 ◽  
pp. 127-131
Author(s):  
Yang Yang ◽  
Kang Min Lee ◽  
Keun Yeong Oh ◽  
Sung Bin Hong

The current local stability criteria (KBC2009, AISC2010) are enacted through theoretical and experimental studies of ordinary steels, but the mechanical properties of high strength steels are different from ordinary steels. The high strength steel in the applicability of design criteria should be needed to review because of increasing market demanding for high strength steel in the high-rise and long span buildings. In this study, stub columns of H-shaped and box section with various steel grades subjected to concentric loading were investigated, and these steels were checked to the applicability of current local stability criteria. The difference between the ordinary steel and high strength steel was compared. As a result of comparison with various steel grades, most specimens were satisfied with the design criteria, but some specimens with lower tensile strength were not reached the required strength. It is considered that the uncertainty of material was the higher when the tensile strength of material was the lower.


Author(s):  
A. R. H. Midawi ◽  
E. B. F. Santos ◽  
A. P. Gerlich ◽  
R. Pistor ◽  
M. Haghshenas

For high productivity weld fabrication, gas metal arc welding (GMAW) is typically used since it offers a combination of high deposition rate and travel speed. Recent advances in power supply technologies have increased the deposition rates in hot-wire tungsten inert gas (HW-TIG) welding, such that it is possible to achieve parameters which may be comparable to those used in GMAW for pressure vessels and some pipeline applications. However, these two processes have drastically different deposition efficiencies and heat input characteristics. The purpose of the present study is to examine GMAW and HW-TIG bead-on-plate deposits in terms of mechanical properties, deposition rate, and heat affected zone (HAZ) thermal cycles when identical travel speed and wire feed speeds are applied with a ER90S-G filler metal. The results demonstrate that HW-TIG can be applied with comparable travel and wire feed speeds to GMAW, while providing a more uniform weld bead appearance. Based on weld metal microhardness values, it is suggested the effective heat input is lower in HW-TIG compared to GMAW, since the average hardness of the weld metal is slightly higher.


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