Step Down test

Step Down ( macro-streak-flaw ) test of steel bar.

Scope:-

This Standard specifies a step-down test method, blue fracture test method and magnetic particle inspection method to assess the non-metallic inclusions in rolled or forged steel with the naked eye or using a magnifying glass with a magnification of not more than 10x.

Test piece:-

The test piece shall be machined to the

dimensions given below in figure table 1 The machined surface shall not be rough but shall be fairly smooth.

Test Procedure Process :-

Sample preparation are complete then ,sample Deep in hydro cloric acid (HCL) temperature 70~80 Degrees centigrade for 1 Hrs.

After process are complete then clean with hot & cold water .

Method of Examination:-

The length and the number of flaws shall be determined under good illumination cither with an unaided eye or with low magnafication 15x

Terminology:-

A:-

For the purpose of this standard the streak flaw shall mean defects arising from non-metalic inclusions, pin holes, blow hoies and the streak

flaws formed by heterogeneous substances such as sand which can be seen on the finished surface ot the test piece. other irregularities in the metal such as cracks, shrinkage cracks or any other working tlaw shall not be considered.

B:-

Steel often differs in inclusion content not only from heat to heat, but also from ingot to ingot in the same heat, and even in different portions of

the content of which is to be determined, should not be larger than one heat. Suficient samples should be selected to adequately represent the

lot. The exact sampling procedure should be incorporated in the individual product requirements or specifcation.the specimens should be selected after the bilets have been sufficiently.

Comments

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