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Customized Threaded Drill Rods Steels

China King-Long Brand Rock Drilling Tools
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King-Long Brand Rock Drilling Tools

A: 50 Years Rock Drilling Production Experience;

B: Country-owned Enterprise Built in year of 1970.

C: 20 Years Drill Steels Study Research Efforts.

D: 10 Years Tungsten Carbides Study Research.

E: 20 Years Sophisticated Production Experience and Rock Drilling Business Service more than 25 countries all around the world.

China King-Long Material is proud to introduce King-Long Thread Drilling Steels: are made from the high steel you can have ever come to expect from China supplier and factories. Our King-Long Brand King-Long Thread Drilling Steels have state-of-the-art treatment is unique- charming and phosphating- manufactured to close tolerances. Our rigorous quality controls at all our manufacturing units ensure that King-Long Brand

Brief Introduction

Hollow rock-drill steel used for rolling the hollow rock-drilling rod is a special alloy steel containing Fe base, W, C, Si, Mn, Cr and V. Its advantages are long service life and high quality.


55SiMnMo: Hollow Drills Steels used for H19 H22 H25 Taper Drill Rods.

35SiMnMoV: D32 D38 Hollow Drill Steels.

Z708 sanbar 61/ 40SiMnCrNiMo: Round Drill Steels, D45 D51.

Sanbar 23/ 25CrNi3Mo Steels: Drill Rod with thread connection. surface hardness HRC58-62. Core hardness: HRC43-45.

Photos of KING-LONG Brand King-Long Thread Drilling Steels

For a hollow steel with the basic dimensions (H and D) ≥32mm, the dimensions and allowable deviation of its core holes at both sides shall be at the same level.

The hollow steel is commonly 6000-7000mm

Through consultation between supply and requisition parties, the hollow steel can be delivered by short dimensions

In case of delivery by specified and multiple lengths, the allowable deviation of the total length shall be 0mm~+60mm





The core hole shall have no sharp (sharp radius <0.5 times radius of the core hole) or obvious deformity, and hollow steels with overrange dimensions can be delivered as long as they will not affect users.

The curvature per meter of hollow steels shall be not more than 2 mm, and the total curvature shall not be more than 0.2% of the total length.

The ends of large-scale hollow steels shall be straight.

The circular arc radius value of the corner of hexagonal hollow steel is for reference only and will not be deemed as the delivery basis.

The ovality of round hollow steel shall be not more than 0.5 times dimensional tolerance of the outer diameter.

The difference of the distance of any two across flats on the same section of hexagonal hollow steel shall be not more than the tolerance of the dimension of across flats.

Decarburized layer

The unilateral decarburized depth of the surface of hollow steels (ferrite+1/2 transition layer) shall be not more than (0.15+1.0%H(D)) mm if the basic dimension is not more than 25.3 mm; and it shall be not more than 1.0% H(D) mm if the basic dimension is more than 25.3 mm.

Surface quality

The surface of hollow steels shall have no crack, scab, inclusion, fold and other defects. Local defects on surface shall be eliminated, and the elimination depth calculated from basic dimensions (H or D) shall be not more than the allowable tolerance of this dimension. In case of the depth less than half of the allowable tolerance, individual scratches, impressions and pocks may not be eliminated.

The surface of the core hole of hollow steels shall have no crack, fold and other defects. Hollow steels shall have no obvious distortion.

Packaging, sign and quality certificate

As for the packaging of hollow steels delivered at common delivery length or non-fixed length, the length difference of each bundle shall be not more than 0.5 mm when one end is parallel and level, and the weight of a bundle shall be not more than 3500kg

Sign and quality certificate

The specification, trade mark, smelting furnace number and weight shall be marked at the side of each bundle of hollow steels. The quality certificate shall contain the specification, chemical components, hardness, decarburized depth and other information.

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