DEFINITION OF FINE GRAIN PRACTICE

[ED1469]

I 'AM AWARE THAT ALUMINIUM IS USED TO REFINE THE GRAIN BUT WHAT IS THE CLEAR DEFINITION OF FINE GRAIN PRACTICE PLEASE HELP I A'M AT WITS END TRYING TO FIND A CLEAR AND PRECISE DEFINITION
THANK YOU

 

[TVP]

The following definition is used in steel specifications like IFI-140 Carbon and Alloy Steel Wire, Rods and Bars for Mechanical Fasteners and ASTM A 29 Standard Specification For Steel Bars, Carbon and Alloy, Hot-Wrought and Cold-Finished, General Requirements for:

7.2 In a fine austenitic grain size is specified, the steel shall have a grain size number of 5 or higher as determined in accordance with Test Methods E 112. Conformance to this grain size of 70% of the area examined shall constitute the basis of acceptance. One test per heat shall be made unless the provision of 7.2.1 is excercised.

7.2.1 When aluminum is used as the grain refining element, the fine austenitic grain size requirement shall be deemed to be fulfilled if, on heat analysis, the aluminum content is not less than 0.020% total aluminum or, alternately, 0.015% acid soluble aluminum. The aluminum content shall be reported. The grain size test specified in 7.2 shall be the referee test.

Nb (often called Columbium, Cb) or V or both can be substituted for Al. The maximum contents are lower than the Al content indicated above.

ASTM standards can be obtained directly from ASTM using the following link:

http://www.astm.org

By the way, the exact title of ASTM E 112 is ASTM E 112 - 96 Standard Test Methods for Determining Average Grain Size.