scholarly journals Method for Theoretical Analysis of Hot Cracking-Solidification Cracking in Laser Surface Melted Region of Austenitic Stainless Steel-

2003 ◽  
Vol 72 (4) ◽  
pp. 264-265
Author(s):  
Hiroaki MORI
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Theoretical Analysis ◽  
Hot Cracking ◽  
Laser Surface ◽  
Solidification Cracking ◽  
Melted Region

Yb:YAG Disc Laser Welding of Austenitic Stainless Steel Without Filler Material

2009 ◽  
Vol 410-411 ◽  
pp. 87-96 ◽  
Author(s):  
Markku Keskitalo ◽  
Kari Mäntyjärvi
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Cross Sections ◽  
Base Material ◽  
Tensile Tests ◽  
Solidification Cracking ◽  
Filler Material ◽  
Test Material ◽  
Butt Weld

The laser weldability of austenitic stainless steel (ASS) is good because of the material’s high absorptivity and favourable microstructure. There can be a slight possibility of solidification cracking at high welding speeds and low Crekv/Niekv ratios. Test welds were welded with a Yb:YAG disc laser. The test material was 3.2 mm EN 1.4404 2H C700 type stainless steel plate which was work hardened by cold rolling. The test materials were welded with different heat inputs ranging from 0.024 kJ/mm to 0.12 kJ/mm and with 300 mm and 200 mm focal lengths. The weld seams were square-groove welded as butt weld without filler material. The edges of the groove were made by mechanical or laser cutting. The hardness profiles from cross-sections of the welds were measured with a Vickers microhardness tester using 200 g weight. The mechanical properties were tested with tensile tests. The welds were classified with radiographic verification by an accredited laboratory. A number of the welds were fatigue tested with a bending fatigue tester. The mechanical properties (Rp 0.2%, Rm) of the laser welds were almost the same as in the base material except at the highest heat input. In the radiographic classification, the welds which were welded to the laser-cut edge were classified as class B (accepted). The other welds were classified as class D or C (rejected). The main reasons for the rejection of welds made on mechanically cut edges were lack of penetration or undercut of the weld. A problem with mechanically cut edges, and hence the welds, is that they can be non-square and bent edge. Fatigue tests and tensile tests gave no evidence of solidification cracking in the microstructure of the solidified parts of the welds.

scholarly journals A New Test Method for Evaluation of Solidification Cracking Susceptibility of Stainless Steel during Laser Welding

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3178 ◽  
Author(s):  
Wenbin Wang ◽  
Li Xiong ◽  
Dan Wang ◽  
Qin Ma ◽  
Yan Hu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Laser Welding ◽  
Cooling Rate ◽  
Weld Joint ◽  
Stainless Steels ◽  
Welding Speed ◽  
Hot Cracking ◽  
Weld Bead ◽  
Test Method ◽  
Solidification Cracking

A new test method named “Trapezoidal hot” cracking test was developed to evaluate solidification cracking susceptibility of stainless steel during laser welding. The new test method was used to obtain the solidification cracking directly, and the solidification cracking susceptibility could be evaluated by the solidification cracking rate, defined as the ratio of the solidification cracking length to the weld bead length under certain conditions. The results show that with the increase in the solidification cracking rate, the solidification cracking susceptibility of SUS310 stainless steel was much higher than that of SUS316 and SUS304 stainless steels during laser welding (at a welding speed of 1.0 m/min) because a fully austenite structure appeared in the weld joint of the former steel, while the others were ferrite and austenitic mixed structures during solidification. Besides, with an increase in welding speed from 1.0 to 2.0 m/min during laser welding, the solidification cracking susceptibility of SUS310 stainless steel decreased slightly; however, there was a tendency towards an increase in the solidification cracking susceptibility of SUS304 stainless steel due to the decrease in the amount of ferrite under a higher cooling rate.

Nitrogen Enhanced 316LN Austenitic Stainless Steel for Sodium Cooled Fast Reactors

2013 ◽  
Vol 794 ◽  
pp. 670-680 ◽  
Author(s):  
Tammana Jayakumar ◽  
A.K. Bhaduri ◽  
M.D. Mathew ◽  
Shaju K. Albert ◽  
U. Kamachi Mudali
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Weld Metal ◽  
Nitrogen Content ◽  
Low Cycle Fatigue ◽  
Hot Cracking ◽  
Cycle Fatigue ◽  
Fast Reactors ◽  
Delta Ferrite ◽  
316Ln Ss

For the future sodium-cooled fast reactors (SFRs), which are envisaged with a design life of 60 years, nitrogen-enhanced 316LN austenitic stainless steel (SS) with improved high-temperature properties is being developed. To optimize the enhanced nitrogen content in 316LN SS, the effect of nitrogen on its tensile, creep and low cycle fatigue behavior has been investigated. For different heats of 316LN SS containing 0.07-0.22 wt% nitrogen, the tensile and creep properties increased with increase in nitrogen content, while low cycle fatigue properties peaked at 0.14 wt% nitrogen. Finally, based on the evaluation of the hot cracking susceptibility of the different heats of 316LN SS with varying nitrogen content, using the Varestraint and Gleeble hot-ductility tests, the nitrogen content for the nitrogen-enhanced 316LN SS has been optimized at a level of 0.14 wt%. The 0.14 wt% nitrogen content in this optimised composition shifts the solidification mode of the weld metal to fully austenitic region, including that due to dilution of nitrogen from the base metal, thereby increasing its hot cracking susceptibility. This necessitated development and qualification of welding electrodes for obtaining weld metal with 0.14 wt% nitrogen by optimising the weld metal chemistry so as to obtain the requisite delta ferrite content, tensile properties, and very importantly impact toughness both in the as-welded and aged conditions. Studies on localised corrosion behaviour of nitrogen-enhanced 316LN SS indicated the beneficial effect of nitrogen addition to sensitization, pitting, intergranular corrosion, stress corrosion cracking and corrosion fatigue.

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