612 Residual Stress Analysis Considering Phase Transformation for Heat-treated Large Shaft

2012 ◽  
Vol 2012.20 (0) ◽  
pp. _612-1_-_612-4_
Author(s):  
Yusuke YANAGISAWA ◽  
Hideo KOEDA ◽  
Katsuhiko SASAKI
1988 ◽  
Vol 110 (4) ◽  
pp. 297-304 ◽  
Author(s):  
E. F. Rybicki ◽  
J. R. Shadley ◽  
A. S. Sandhu ◽  
R. B. Stonesifer

Residual stresses in a heat treated weld clad plate and test specimens obtained from the plate are determined using a combination of experimental residual stress analysis and a finite element computational model. The plate is 102 mm thick and made of A 533-B Class 2 steel with 308 stainless steel cladding. The plate is heated to 538 C and allowed to cool uniformly. Upon cooling, residual stresses are set up in the clad plate because of the difference between the coefficients of thermal expansion of the plate and the cladding. Residual stress in the clad plate is determined using both a previously verified experimental residual stress analysis technique and a computational model. Removing test specimens from the clad plate can relax the stresses in the cladding. Thus, residual stress distributions were also determined for two types of clad test specimens that were removed from the plate. These test specimens were designed to examine the effect of cladding thickness on residual stresses. Good agreement was found between the experimentally obtained residual stress values and the residual stresses calculated from the computational model. Because of the interest in tests conducted at elevated temperatures and the inherent difficulty in doing experimental residual stress analysis at elevated temperatures, the computational model was applied to examine the effect of elevated temperature on the residual stresses in the test specimens. Peak stresses in the heat treated clad plate were found to approach the yield stress of the cladding material. It was also found that removing a 32 mm clad specimen with cladding on one side reduced the residual stresses in the cladding. However, the residual stresses in the cladding were found to increase when one-half of the cladding thickness was machined away to form the second test specimen geometry. Residual stresses parallel and perpendicular to the weld direction were very similar in magnitude for all cases considered. The effect that heating the test specimens to 204 C has on residual stress distributions was to reduce the residual stress in the cladding and the plate.


Author(s):  
Nobuyoshi Yanagida ◽  
Koichi Saito

We developed a residual stress analysis method for bead welded low alloy steel JIS SQV2A (equivalent to ASTM A533B cl. 1) plates subjected to post weld heat treatment (PWHT). Two specimens were fabricated; each was a bead welded low alloy steel plate. One was in the as-welded condition (as-welded specimen) and the other was subjected to PWHT at 625°C (PWHT specimen). Strain gauges were used to measure the distributions of the residual stress in these specimens. The measurement data showed that the longitudinal stress at the center of a bead was 0 MPa and that in the heat-affected zone was 100 MPa. The transverse stress at the center of a bead was 200 MPa in the as-welded specimen. The absolute residual stress was decreased to less than 50 MPa for the PWHT specimen. We conducted finite element analyses to predict the distributions of welding residual stress in these specimens. The amount of phase transformation strain in low alloy steel was taken into account in the welding residual stress analysis, and creep strain was taken into account in the stress mitigation analysis. The results from the analyses agree well with the experimental results. These findings prove that welding residual stress can be simulated during a thermal elastic plastic (TEP) analysis by conducting a phase transformation and taking the generation of creep strain in the PWHT samples into consideration can be used to simulate that stress mitigation.


2018 ◽  
Vol 941 ◽  
pp. 1288-1294 ◽  
Author(s):  
Dimitry Sediako ◽  
Joshua Stroh ◽  
Alexandra McDougall ◽  
Ermia Aghaie

Mercury Marine has used a new alloy, Mercalloy A362, for the manufacturing of a re-designed lower unit transmission gearcase. The enhanced strength of the alloy allowed for a substantial weight reduction in the new design. The purpose of this study was to examine and determine why cracking may develop in the gear casing during in service testing. Two types of material states, (i) as cast and (ii) heat treated were compared. Metallography and neutron diffraction analysis was carried out at locations identified as being areas of high stress by Magma software – which was performed in a separate study. Microstructural characterization at these locations revealed microstructural and the compositional differences. Differences in the porosity, eutectic phase, and volume fraction of the precipitates were observed at various locations of interest in each material state. The residual stress analysis was performed with application of neutron diffraction and revealed that the stresses in the as-cast component reached a maximum value of 120 MPa, which is below the yield strength of the alloy. The heat treatment applied to the castings reduced the stress by approximately 50 MPa. Based on the microstructure and neutron diffraction results, it is likely that performing a heat treatment process extends the lifetime of the component, however, it may not completely eliminate the cracking problem. Farther studies are currently nearing completion, targeting the mass production of the redesigned gearcase.


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