JB/T 9986-2013Metallographic examination of heat treated tools (English PDF)

1 Scope

This standard specifies the technical requirements, the acceptance provisions, the test methods, the assessment method and the rating criteria for the metallographic examination of heat treated tools.

It applies to the examination of the metallographic structure, after normal heat treatment, of cutting tools and measuring tools made of high speed tool steel, low alloy high speed steel, alloy tool steel, carbon tool steel, stainless steel and high carbon chromium bearing steel.

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition, including any amendments, applies.

GB/T 6394-2002 Determination of estimating the average grain size of metal

JB/T 3912 Quality inspection of steam treatment and oxynitriding of high speed steel cutting tools

3 Technical requirements

After heat treatment, the technical requirements for the metallographic examination of a product follow Table 1, Table 2, Table 3, Table 4, Table 6 and Table 8 according to the grade of steel. The martensite needle length of each grade of alloy tool steel, carbon tool steel and stainless steel follows Table 5 and Table 7. For products not listed in the tables, this standard may be taken as a reference according to the characteristics of the intended use of the product.

Table 1 covers cutting tools made of high speed tool steel and gives, for each product, the quenching grain size of the W-Mo series and of the W series, the acceptable grade for degree of overheating and the acceptable grade for degree of tempering, which is grade 2 or finer throughout the table.

Straight shank drills: diameter not greater than 3 mm, grain size 10 to 12 for the W-Mo series and 10 to 11,5 for the W series, overheating grade 1 or finer; diameter over 3 mm up to and including 20 mm, grain size 9,5 to 11 and 9,0 to 10,5, overheating grade 2 or finer.

Centre drills: grain size 10 to 11,5 and 9,5 to 11, overheating grade 1 or finer.

Taper shank drills: diameter not greater than 30 mm, grain size 9,5 to 11 and 9,0 to 10,5; diameter over 30 mm, grain size 9,0 to 10,5 and 8,5 to 10; overheating grade 2 or finer.

Slitting saws and saw blade milling cutters: thickness not greater than 1 mm, grain size 10 to 11,5 and 9,5 to 11, overheating grade 1 or finer; thickness over 1 mm, overheating grade 2 or finer.

Milling cutters and reamers: grain size 9,5 to 11 and 9 to 10,5, overheating grade 2 or finer.

Turning tools: section not greater than 16 mm by 16 mm, grain size 8,5 to 10,5 and 8 to 10, overheating grade 2 or finer; section over 16 mm by 16 mm, overheating grade 3 or finer.

Gear cutting tools: grain size 9 to 11 and 9,0 to 10,5, overheating grade 2 or finer.

Thread cutting tools: grain size 10 to 11,5 and 9,5 to 11, overheating grade 1 or finer.

Broaches: grain size 9 to 11 and 9,0 to 10,5, overheating grade 1 or finer.

Note: for powder metallurgy high speed tool steel the degree of overheating is grade 1 or finer and the quenching grain size is number 10 or finer; because the grain is fine, the Snyder-Graff grain size may be used for the rating. For high performance high speed tool steels such as M42 and M35 the degree of tempering is grade 1.

Note: for drills, keyway milling cutters and end mills, the grade for degree of overheating where carbide has built up at the cutting edge through the centre may be grade 3 or finer.

Note: shaving cutters shall not be overheated.