Hello Bhattacharyya,
The Below Settings for WebService SGNInventQuarantineServiceHttpPort and the same settings are available for Default Website :

the below picture shows the application pool where ErpUser is defined at Identity column and by default the service is running on behalf of this user ( this user is get registered on AX Tables )

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For Below Code , I am able to process the operations but the operations are performed behalf of ErpUser ( The Modified field in AX Table is ErpUser )
client.ChannelFactory.Credentials.UserName.UserName = @"sgn\ErpTest";
client.ChannelFactory.Credentials.UserName.Password = @"Axa6";
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For Below Code , I am able to process the operations but the operations are performed behalf of ErpUser ( The Modified field in AX Table is ErpUser )
client.ClientCredentials.UserName.UserName = @"sgn\ErpTest";
client.ClientCredentials.UserName.Password = @"Axa6";
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For Below Code, I am getting this error "{"Failed to logon to Microsoft Dynamics AX."}"
client.ClientCredentials.Windows.ClientCredential.UserName = @"sgn\ErpTest";
client.ClientCredentials.Windows.ClientCredential.Password = @"Axa6";
I want to have ErpTest User should be effected on AX Tables .
I request to community to kindly suggest me for the above problem
Thanks In Advance.