scholarly journals Underwater In Situ Local Heat Treatment by Additional Stitches for Improving the Weldability of Steel

2020 ◽  
Vol 10 (5) ◽  
pp. 1823 ◽  
Author(s):  
Jacek Tomków ◽  
Anna Janeczek
Keyword(s):  
Heat Treatment ◽  
Hsla Steel ◽  
Water Environment ◽  
High Strength ◽  
Hardness Measurement ◽  
Local Heat ◽  
Cold Cracking ◽  
Local Heat Treatment ◽  
The Face

In this paper the influence of in situ local heat treatment performed by additional stitches on the weldability of high-strength low-alloy (HSLA) S355J2C+N steel was tested. The investigated steel is characterized by high susceptibility to cold cracking. It is necessary to find a method to improve the quality of welded joints. The local heat treatment was applied as an effect of bead-on plate welding made on the face of a Tekken test joint. The specimens were made by the use of covered electrodes in the water environment. For testing weldability, Tekken test specimens were made. Then, the different number of the pad welds with different overlapping were laid on the face of the tested welds. Non-destructive (NDT) visual and penetrant tests were undertaken. During the NDT, imperfections like shape mistakes and spatters were found. Then, metallographic macro- and microscopic testing were performed. The macroscopic observations proved that water environment can generate imperfections like cracking and pores. However, for specimens with additional stitches the number of imperfections decreased. Microscopic tests proved that the proposed technique affected the structure of the heat-affected zone (HAZ). The specimens without the application of additional stitches are characterized by brittle bainitic and martensitic structure. Specimens, in which the additional stitches were applied, contain tempered martensite, fine ferrite and fine pearlite in their HAZ. It was also observed that the number of cracks decreased for in situ local heat-treatment specimens. The final step was Vickers HV10 hardness measurement. These measurements confirmed previous results. The heat from additional stitches affected the steel by significantly decreasing the hardness by 80–100 HV10. The results of experiments showed that the heat from pad welds provided microstructural changes in heat-affected zones and a decrease in the susceptibility to cold cracking, which results in improvement in the weldability of HSLA steel in wet welding conditions.

scholarly journals Temper Bead Welding of S460N Steel in Wet Welding Conditions

2018 ◽  
Vol 18 (3) ◽  
pp. 5-14 ◽  
Author(s):  
J. Tomków ◽  
D. Fydrych ◽  
G. Rogalski ◽  
J. Łabanowski
Keyword(s):  
Heat Affected Zone ◽  
Hsla Steel ◽  
Water Environment ◽  
High Strength ◽  
Offshore Structures ◽  
Cold Cracking ◽  
Common Method ◽  
Maximum Hardness ◽  
High Susceptibility ◽  
Welding Condition

AbstractWet welding is the most common method of welding in water environment. It is most often used for repairing of underwater parts of offshore structures. However, the water as a welding environment causes an increase of susceptibility of steels to cold cracking. For underwater constructions high strength low alloy (HSLA) steel are widely used. In wet welding condition a HSLA steel is characterized by high susceptibility to cold cracking. Temper Bead Welding (TBW) was chosen as a method to improve the weldability of S460N steel. The studies showed that TBW technique causes significant decrease of maximum hardness of heat affected zone (HAZ). The largest decrease in hardness occurred in specimens with the pitches in range 66-100%.

Local heat treatment of high strength steels with zoom-optics and 10kW-diode laser

2012 ◽  
Author(s):  
Markus Baumann ◽  
Volker Krause ◽  
Georg Bergweiler ◽  
Martin Flaischerowitz ◽  
Janko Banik
Keyword(s):  
Heat Treatment ◽  
Diode Laser ◽  
High Strength Steels ◽  
High Strength ◽  
Local Heat ◽  
Local Heat Treatment

Manufacturing of Parts in Ultra High Strength Steel Using Local Heat Treatment

2006 ◽  
Author(s):  
Bjo¨rn Carlsson ◽  
Domenico Russo ◽  
Jesu´s Arin˜o Oliver
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
High Strength ◽  
Local Heat ◽  
Side Impact ◽  
Risk Of Fracture ◽  
Tailor Welded Blanks ◽  
Local Heat Treatment ◽  
Heat Treated ◽  
Ultra High Strength Steel

In this paper the manufacturing of a side impact beam, with the aid of local heat treatment, is described. The beam has two areas where the risk of fracture is high. Two zones of the blank, corresponding to these areas, are therefore heat treated before stamping to reduce the risk of fracture. The material is a martensitic steel with a virgin tensile strength of 1200 MPa. The heat treatment is made by laser to an approximate temperature of 850° Celsius. This heat treatment reduces the strength of the material to a tensile strength of approximately 650 MPa after cooling. The formability is increased accordingly. The method of local heat treatment with the objective to increase formability in selected areas can be seen as an alternative to the use of conventional tailor welded blanks.

Improvement of Fatigue Properties of Fillet Lap Joints by Applying. Local Heat Treatment with TIG Arc.

1999 ◽  
Vol 17 (2) ◽  
pp. 319-325 ◽  
Author(s):  
Koichi OSAWA ◽  
Tsuyoshi SHIOZAKI ◽  
Toshiaki URABE ◽  
Akihide YOSHITAKE ◽  
Takanobu SAITO ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Local Heat ◽  
Lap Joints ◽  
Fatigue Properties ◽  
Local Heat Treatment

Comparison of Microstructure and Mechanical Properties of Additively Manufactured and Conventional Maraging Steel

2020 ◽  
Vol 405 ◽  
pp. 133-138
Author(s):  
Ludmila Kučerová ◽  
Andrea Jandová ◽  
Ivana Zetková
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Maraging Steel ◽  
Precipitation Hardening ◽  
High Strength ◽  
Hardness Measurement ◽  
Nickel Steel ◽  
Heat Treated ◽  
Good Material ◽  
Iron Nickel

Maraging steel is an iron-nickel steel alloy, which achieves very good material properties like high toughness, hardness, good weldability, high strength and dimensional stability during heat treatment. In this work, maraging steel 18Ni-300 was manufactured by selective laser melting. It is a method of additive manufacturing (AM) technology, which produces prototypes and functional parts. Sample of additively manufactured and conventional steel with the same chemical composition were tested after in three different states – heat treated (as-built/as-received), solution annealed and precipitation hardened. Resulting microstructures were analysed by light and scanning electron microscopy and mechanical properties were obtained by hardness measurement and tensile test. Cellular martensitic microstructures were observed in additively manufactured samples and conventional maraging steel consisted of lath martensitic microstructures. Very similar mechanical properties were obtained for both steels after the application of the same heat treatment. Ultimate tensile strengths reached 839 – 900 MPa for samples without heat treatment and heat treated by solution annealing, the samples after precipitation hardening had tensile strengths of 1577 – 1711 MPa.

Sign in / Sign up

Export Citation Format

Share Document