Influence of Weld Discontinuities on Strain Controlled Fatigue Behavior of 308 Stainless Steel Weld Metal

1994 ◽  
Vol 116 (2) ◽  
pp. 193-199 ◽  
Author(s):  
K. Bhanu Sankara Rao ◽  
M. Valsan ◽  
R. Sandhya ◽  
S. L. Mannan ◽  
P. Rodriguez
Keyword(s):  
Stainless Steel ◽  
Weld Metal ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Base Material ◽  
Welding Process ◽  
Single Strain ◽  
Damage And Fracture ◽  
Slag Inclusions ◽  
Type 304

Detailed investigations have been performed for assessing the importance of weld discontinuities in strain controlled low cycle fatigue (LCF) behavior of 308 stainless steel (SS) welds. The LCF behavior of 308 SS welds containing defects was compared with that of type 304 SS base material and 308 SS sound weld metal. Weld pads were prepared by shielded metal arc welding process. Porosity and slag inclusions were introduced deliberately into the weld metal by grossly exaggerating the conditions normally causing such defects. Total axial strain controlled LCF tests have been conducted in air at 823 K on type 304 SS base and 308 SS sound weld metal employing strain amplitudes in the range from ±0.25 to ±0.8 percent. A single strain amplitude of ±0.25 percent was used for all the tests conducted on weld samples containing defects. The results indicated that the base material undergoes cyclic hardening whereas sound and defective welds experience cyclic softening. Base metal showed higher fatigue life than sound weld metal at all strain amplitudes. The presence of porosity and slag inclusions in the weld metal led to significant reduction in life. Porosity on the specimen surface has been found to be particularly harmful and caused a reduction in life by a factor of seven relative to sound weld metal. Defect combination of porosity and slag inclusions was found to be more deleterious than the case when either the slag inclusions or porosity was present alone. Discontinuties acted as crack initiation sites and also enhanced crack propagation. The LCF properties of weld samples containing discontinuities have been correlated with the damage and fracture behavior.

Low-Cycle Fatigue Properties of Steels and Their Weld Metals

1989 ◽  
Vol 111 (4) ◽  
pp. 431-437 ◽  
Author(s):  
Y. Z. Itoh ◽  
H. Kashiwaya
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Weld Metal ◽  
Arc Welding ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Steel Weld ◽  
Cycle Fatigue ◽  
Weld Metals ◽  
Metal Arc Welding

Completely reversed, strain-controlled, low-cycle fatigue behavior at room temperature is investigated for steels and their weld metals. Weld metal specimens were taken from multi-pass weld metal deposited by shield metal arc welding (SMAW) and gas metal arc welding (GMAW), such that their gage length consisted entirely of the weld metal. Results indicate that there is a trend toward reduction in the low-cycle fatigue life of weld metals as compared with the base metals. In low carbon steel weld metals, the tendency described above is explained in terms of local plastic strain concentration by lack of uniformity of the multi-pass weld metals. The weld metals do not have the same mechanical properties anywhere as confirmed by hardness distribution, and the fatigue crack grows preferentially through the temper softened region in the multi-pass welds. In Type 308 stainless steel weld metals, the ductility reduction causes reductions in low-cycle fatigue life. This study leads to the conclusion that fairly accurate estimates of the low-cycle fatigue life of weld metals can be obtained using Manson’s universal slope method. However, life estimates of the Type 304 stainless steel is difficult due to a lack of ductility caused by a deformation-induced martensitic transformation.

An assessment of cold work effects on strain-controlled low-cycle fatigue behavior of type 304 stainless steel

1993 ◽  
Vol 24 (4) ◽  
pp. 913-924 ◽  
Author(s):  
K. Bhanu Sankara Rao ◽  
M. Valsan ◽  
R. Sandhya ◽  
S. L. Mannan ◽  
P. Rodriguez
Keyword(s):  
Stainless Steel ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cold Work ◽  
304 Stainless Steel ◽  
Cycle Fatigue ◽  
Type 304 ◽  
Type 304 Stainless Steel

scholarly journals High Martensitic Steel after Welding with Micro-Jet Cooling in Microstructural and Mechanical Investigations

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 936
Author(s):  
Bożena Szczucka-Lasota ◽  
Tomasz Węgrzyn ◽  
Tadeusz Szymczak ◽  
Adam Jurek
Keyword(s):  
Tensile Strength ◽  
Weld Metal ◽  
Fatigue Limit ◽  
Relative Elongation ◽  
Fatigue Behavior ◽  
Base Material ◽  
Welding Process ◽  
Heat Affect Zone ◽  
Jet Cooling ◽  
Metal Deposit

Modern means of transport will play a significant role in the smart city. In the automotive industry, high-strength steels such as Docol are employed more often. This kind of material is relatively not very well weldable. The main reason is related to the Heat Affect Zone, the region in which cracks occur. Another disadvantage is connected with differences in values of ultimate strength of parent and weld material. The differences can be diminished using the correct welding process, which employs nickel and molybdenum electrode wires at much lower sulfur content. The weld metal deposit contains mainly martensite and bainite with coarse ferrite, while the parent material contains mainly martensite and rather fine ferrite. New technology, micro-jet cooling after the joining process enables to obtain the microstructure of weld metal deposit at acceptable parameters. Welding with micro-jet cooling could be treated as a very promising welding Docol steels process with high industrial application. Results of non-destructive inspections on macro samples corresponded with further destructive test results (tensile strength, hardness, fatigue, metallographic structure analyses). This article aims to verify fatigue behavior of Docol 1200 M steel after welding supported by the cooling using the micro-jet technique. For the first time, micro-jet cooling was used to weld this kind of steel to check the mechanical properties of the joint, especially to determine the fatigue limit. This study is formulated as follows: investigating fatigue resistance of the Docol 1200 M weld manufactured at the cooling process with micro-jets. The joints were produced in the MAG (Metal Active Gas) technology modified by micro-jet cooling. The results collected in the fatigue test were processed in the form of the Wöhler’s S–N diagram following the fatigue limit of the weld examined. All data have indicated the possibility of obtaining a new method of welded joints with high fatigue limit minimum of 480 MPa. It could be important to achieve a tensile strength of 700 MPa while maintaining the best relative elongation at the level of the base material.

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