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Dear all, I am puzzled with the microstructure found in the vessel made of A240 Grade 347. We used replica technique to pick up the microstructure using 10% oxalic acid. I can see twins inside the prior austenite grains with black dots along the boundary. Are they carbides of artefact due to...

Dear all, I need some help...I come across the specification for austenitic stainless steel SA403 WP316/316LW for the fitting (Elbow) I am just wondering what is 316/316LW referring to ? Is it dual certificate 316 and 316L with W stand for welded? Any info will be highly appreciated....

Dear all, Any idea of what might be the cause of the localized corrosion of the carbon steel in the seawater as in the attached photographs. The part in the photo was taken from the flange of the floating reducer that was exposed to seawater for 5 years. The floating reducer was used to...

Hi all, Does anybody know about the effect of sand blasting on the SS304 stainless steel plate to remove oxide scales? I had come across on the procedure of shot peening on the internal surface of tube (in contact with steam) was implemented by the boiler tube manufacturer to improve the...

Dear all, Is it possible to see creep cavities in short overheating tube that caused stress rupture with fish mouth appearance? As far as I know creep is time depending so for short term overheating.....we cannot see cavities..Am I right?

Dear all, What is the main different between killed and semi killed steel? If the aluminum is used as oxidizer for semi killed steel and produced aluminum oxide inclusions it is by having fully killed steel will has lower amount of aluminum oxide inclusion and other inclusions? If I want to...

Hi all, Any idea on why the hardness values for the SA335 304H, SA312 304H and SA403M WP304H stainless steel and most of the stainless steels are not mentioned in the specification? The hardness for stainless steel is only specified in SA231 tubes. Can we take minimum tensile strength in...

Dear all, Anyone know about the minimum carbon Wt% for API 5L X60. According to the specification the maximum carbon content 0.28 wt%. My PMI results shows the carbon content of 0.05 wt%. However the microstructure is tempered martensite with the hardness of 210HV, Yield strength of 520 MPa...

Hello everyone, I am a little bit confused regarding the sensitization of 304 and 316 austenitic stainless steel . Does sensitization takes place during prolong holding at the sensitization temperature range or during cooling from high temperature and reaching the sensitization temperature or...

Dear all, Is there any difference in the hardness values when using 5 kg load and 10 kg load for portable vickers hardness tester model kraukramer Microdur UCI MIC 10?

Dear all, I have two questions to ask: 1. Can martensitic stainless steel crack due to chloride stress corrosion cracking (ClSCC) similar to austenitic stainless steel?. I was informed that martensitic stainless steel is not prone to ClSCC but prone to hydrogen stress corrosion cracking or...

Dear all, Can we weld SS304 to T91? What is the filler metal used and do we need PWHT? Any comment is highly appreciated.

Hello everyone, Anybody know about super stainless steel 304 that is used in super critical temperature boiler in power plant. I was informed that the as supplied material's hardness for this material is low but will increase during heating/operation due to the precipitation of Cu ...which will...

Hi all, I am a little bit confused on the selection of super heater tube temperature to identify whether the tube is operating above or below the creep threshold temperature values. Should I use the steam temperature or flue gas temperature for the creep threshold value? If I take the replica...

Dear all, Is it possible to carburise TP SS304H stainless steel convection tube at 450C with exhaust gas containing source of carbon? As far as I know the temperatrure is too low for the low temperature carburization to take place. Can the carbon potential influence the carburization and can...

Dear all, Why is the maximum hardness value for the pipes in ASTM 335 not specified but is specified for the tubes in ASTM A213?..Can we use the values stated in ASTM A213 for A335? Any comment is highly appreciated?

Dear all, Any idea what is the possible cause of the failure of this angular contact ball bearing? Attached is the photograph of the ball bearing 14 out of 15 balls have the similar pattern on the ball with the initiation site at the center and propagate radially like fatigue striation. The...

Dear all, I did the hardness measurement on the 316L boiler tube and always found that the average values are higher than 192HB as specified in ASTM 213 316L. The value can be ranging from 213HB to 280HB. Are these values acceptable? Similarly when I did the hardness measurement on the plate...

Dear all, I have done hardness measurement on the 6" pipe of A106 Gr. B material and found that the average values are between 130 HB and 218 HB. I know that the hardness value is not specified in ASTM A106 Gr. B and only the minimum UTS of min. 415MPa was specified. Can I use this UTS of 415...

Dear all, We had an issue of fire outbreak on the equipment that consisted of component made of A516 grade 70, A516 Grade 60, A106 Grade B and A105 materials. The issue is if the components had been heated to above Ac1 line ..approximately 723C and cooled slowly...ie air or furnace cool...and...