Why hot rolled fully thread rebars are not continuously threaded?

http://www.longtonsteel.com/hot-rolled-fully-screw-thread-bar-rock-bolt.html

Fully thread rebar and rock bolt are Anyang Longteng’s star products, which are widely used for pre-stressing and post-tesnioning purposes.  

The reason why it’s chosen is, despite its high mechanical properties, but also because it can fit a nut directly without screw a new thread. 

But Why these threads are not continuous?

As we all know, threads can be cut, cold-rolled, and cast. These hot-rolled pre-stressing rebars are cast by modules. During production, there are two modules cover the rod body, then the thread shape. So there are always a gap that haven’t been covered. So this is why the thread is not continuous on hot-rolled fully thread rebars. But don’t worry, the nuts can still fastened well enough.

pre-stress rebar appearance

Rolling Method: Hot rolled, Heat-treated

Grade: PSB500, PSB780, PSB830, PSB930, PSB1080

Standard: KSD3504, JIS3112,CAN/CSAG30.18-M92,BS4449-1998,ASTM615/706, DIN488-1

Diameter: regular 15, 20, 25, 28, 32, 36, 40, 50 mm or as customer’s demands

Length: As customer’s demands

Yield strength: 500/780/830/930/1080 MPa

Tensile strength: 630/980/1030/1080/1230 Mpa

Accessories: Full force hex nut, dome washer, bearing plate, coupler, nylon nut

Place of origin: China

Brand Name: LT

Application: Mining, tunneling, construction,slope stabilization

Supply ability: 500 Tons per month

Steel Grade Yield Strength
MPa
Tensile Strength
MPa
Elongation after Fragure
A%
uniform Elongation
Agt%
Stress Relaxation
Original Stress Relaxation rate after 1000h r/%
PSB500 ≥500 ≥630 ≥10 ≥2.5 ≤3
PSB780 ≥780 ≥980 ≥7 ≥3.5 0.8R ≤3
PSB830 ≥830 ≥1030 ≥6 ≥3.5 0.8R ≤3
PSB930 ≥930 ≥1080 ≥6 ≥3.5 0.8R ≤3
PSB1080 ≥1080 ≥1230 ≥6 0.8R ≤3

 

Nominal Diameter, mm Nominal Cross Section Area, mm² Theoretical Weight. kg/m
6(6.5) 28.27(33.18) 0.222(0.260)
18 254.5 2
20 314.2 2.47
22 380.1 2.98
25 490.9 3.85
28 615.8 4.83
32 804.2 6.31
36 1018 7.99
40 1257 9.87
50 1964 15.42
Theoretical weight in this table is according to steel density 7.85g/cmm³.

 

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Post time: Apr-10-2019