1. Hex Socket Head Cap Screws1 4 . 9
“ULTRA-HIGH TENSILE
STRENGTH”
Hex Socket Head Cap Screws
Yura Sansho Co., Ltd

2. Ultra high tensile strength
Ultra High Tensile Strength 14.9 Hex Socket Head Cap Screws
We have developed 14.9 ultra-high strength socket head cap screws with KYOKUTO MFG. CO., LTD. who has advanced technology and good fame in Japan.
It is made of the special low alloy steel which have been developed for high tensile strength and for high delayed fracture resistance, called KNDS4, using MJ thread to improve fatigue strength and realize minimum tensile strength 1,400N/mm2 with elongation 9%.
Ultra high tensile strength
■Comparison　of mechanical property
Grade
Tensile strength
（N/mm²）　
0.2％Yield strength
（N/mm²）
Proof Load
Elongation
（％）
8.8
800
640
580 12
10.9
1,000
900
830 9
12.9
1,200
1,080
970 8
14.9
1,400
1,260
1,120
◆Loosening prevention by the improvement of clamp force
and thread accuracy(MJ4g6g).
◆Realization of compact design by size down according to the
improvement of clamp force.
◆Improvement of anti-seizing-tendency by higher tensile
strength.
◆Reducing seizing-tendency of the thread and bearing
surface by improvement of surface hardness.
◆To cope with leaking oil and other leaking by high axial strength
Due to high axial strength, it makes close adhesion with mating bearing
surface. Then it can cope with leaking problem.
◆Superior reusability
　In result of increasing surface hardness, superior reusability is realized by
preventing deterioration on the thread when tightened. 1

3. High delayed fracture resistance
Ultra High Tensile Strength 14.9 Hex Socket Head Cap Screws
Fatigue resistance
・Extension in service life by the improvement of fatigue resistance
adopt aerospace specification 「MJ Thread」
adopt the root design and imperfect thread design of stress concentration area for
improving fatigue resistance.
■MJ Thread
MJ Thread is aerospace specification per ISO Compared with normal standard, the thread root of MJ thread is shallower and the root radius become larger to　improve　fatigue resistance by the relaxation of notch effect.
MJ Thread
Regular Thread
■The radius of Incomplete thread run out
It is to reduce the load of stress concentration area by making the root of incomplete thread round.
●By radius chamfering dice
●By common chamfering dice
■Thread tolerance system　:　　example M8 x 1.25P (in mm)
Pitch diameter tolerance for internal thread (TD2)
Pitch diameter tolerance for external thread (Td2)
Basic line ES es ei
Yura 14.9
ISO-5855
Hex Socket
Cap Screws
JIS B 1176
(ISO 4762)
Hex Cap Screws
JIS B 1180
(ISO 4014/4017)
High delayed fracture resistance
◆Improvement for the risk against delayed fracture
◆The material is developed for high strength steel bolts with high delayed fracture resistance named KNDS4 made by Kobe Steel, Ltd.
（Please refer the details of KNDS4 at page5-6.）
Stress
concentration
zone
Diffusible
hydrogen
Crack occurs at the stress
concentration zone
①Reduction of hydrogen intrusion
②Increase of hydrogen trap site
③Improvement of limited diffusible
hydrogen amount
■ What is the design concept of KNDS4 whose aim is to improve the delayed fracture resistance? 2

4. Specification・Dimension・Stock Range Hex Socket Head Cap Screws
Material
KNDS4 (steel for high strength bolts)
made by Kobe Steel, Ltd.
Property Class
14.9
Tensile Strength
1,400N/mm² min.
Yield Strength
1,260N/mm² min.
Proof Load
1,120N/mm² min.
Elongation
9％ min
Hardness
HRC 44～50
Specification
JIS B 1176/ISO 4746
Thread
ISO MJ Thread
（Aerospace specification）
Thread Class
4ｇ6ｇ
Surface Finish
Black oxide
Min.120℃
Max. 2P
■Dimensions　
(ｍｍ)
Nominal
diameter
（ｄ）　
Pitch dk da ds e k s t P
Max
Min M3
0.5
5.68
5.32
3.6
3.00
2.86
2.873
4.00
2.5
2.56
2.52
1.3 M4
0.7
7.22
6.78
4.7
3.82
3.443 3
3.08
3.02
2.0 M5
0.8
8.72
8.28
5.7
5.00
4.82
4.583 4
4.095
4.020 M6
1.0
10.22
9.78
6.8
6.00
5.82
5.723
5.70 5
5.095
5.020
3.0 M8
1.25
13.27
12.73
9.2
8.00
7.78
6.863
7.64 6
6.095
6.020
4.0
M10
1.5
16.27
15.73
11.2
10.00
9.149
9.64 8
8.115
8.025
5.0
M12
1.75
18.27
17.73
14.2
12.00
11.73
11.429
11.57 10
10.115
10.025
6.0
M16
24.33
23.67
18.2
16.00
15.996
15.57 14
14.142
14.032
8.0
■Stock Range 5 6 8 10 12 15 16 18 20 22 25 30 35 40 45 50 55 60 65 70 75 80 90
100
110
120
130
140
150 M3 ● ○ M4 M5 M6 M8
M10
M12 ○　
M16
※●Full threaded、○Half threaded 3

5. Tightening torque(N･m)※
Specification・Dimension・Stock Range
Hex Socket Head Cap Screws
■Tolerance Class of MJ-4g6g
（conform to ISO ）
(ｍｍ)
Nominal
pitch
Pitch
Major diameter 6g
Pitch diameter 4g
Minor diameter MJ4g
Root radius MJ4g P
Max
Min M3
0.5
2.980
2.874
2.655
2.607
2.403
2.324
0.090
0.075 M4
0.7
3.978
3.838
3.523
3.467
3.170
3.071
0.126
0.105 M5
0.8
4.976
4.826
4.456
4.396
4.052
3.944
0.144
0.120 M6
1.0
5.974
5.794
5.324
5.253
4.819
4.687
0.180
0.150 M8
1.25
7.972
7.760
7.160
7.085
6.529
6.378
0.226
0.188
M10
1.5
9.968
9.732
8.994
8.909
8.236
8.060
0.271
0.225
M12
1.75
11.966
11.701
10.829
10.734
9.945
9.744
0.316
0.263
M16
2.0
15.962
15.682
14.663
14.563
13.653
13.431
0.361
0.300
※When the tolerance of internal thread is strict, it is recommended to confirm the tolerance
　for fitting or make fitting test in advance because the root radius of MJ specification is　　
　larger compared with normal standard. Because its tolerance class is 4g6g.
(It is OK in case it is the standard internal thread of JIS/ISO.)
■Comparison of tensile load, proof load, tightening strength and torque（for reference)
Stress area
Min. Tensile load(kN)
Proof load(kN)
Clamping force(kN)※
Tightening torque(N･m)※
(mm²)
10.9
12.9
14.9 M3
5.03
5.2
6.1
7.0
4.2
4.9
5.6
3.3
3.9
4.4
1.7
2.0
2.2 M4
8.78
9.1
10.7
12.3
7.3
8.6
9.8
5.8
6.8
7.7
4.6 M5
14.2
14.8
17.3
19.9
11.8
13.9
15.9
9.3
12.5
7.9
10.6 M6
20.1
20.9
24.5
28.1
16.7
19.5
22.5
13.2
15.5
17.7
13.5
15.8
18.1 M8
36.6
38.1
44.6
51.2
30.4
35.5
41.0
24.1
28.2
32.3
32.8
38.4
43.9
M10
58.0
60.3
70.8
81.2
48.1
56.3
65.0
38.2
44.7
64.9
76.0
87.0
M12
84.3
87.7
103.0
118.0
70.0
81.8
94.4
55.5
74.4
113.2
132.4
151.8
M16
157.0
163.0
192.0
220.0
130.0
152.0
176.0
103.3
120.9
138.5
281.0
328.8
376.7
Note: please make sure of the clamp force/torque before tightening.
　※Please conform to JIS B 1083 etc. for detail when used. Because the figures above are
　　for reference.
　※Tightening torque(T)=KdF　K=Torque coefficient(0.17)、d=Nominal diameter、　
　　F=70%Yield load　 4

6. High corrosion resistance
14.9 Hex Socket Head Cap Screws With Zinc flake Coating
Material
KNDS４(steel for high strength bolts and for delayed fracture resistance)　
Tensile Strength
1,400 N/mm²
Yield Strength
1,260 N/mm²
Hardness
HRC 44～50
Thread
ISO 5855－1　MJ Thread
（Aerospace specification）
Thread Class
4g6g （Before coating）
※Maximum thread tolerance 4h after coating
Surface Treatment
Micro-layer anti-corrosion coating with zinc flake
Chromium-Free
Surface Treatment
※Dimension is the same with standard products at Page 3.
☞Realization of Fastener with
ultra-high tension and anti-corrosion!! 10 12 15 16 20 25 30 35 40 45 50 M6 ● M8 ○
M10
M12
※●Full threaded、○Half threaded
■Stock Range
High corrosion resistance
・Without the risk of hydrogen embrittlement fracture
　 Because no hydrogen occurs in process of coating.
・Thin and uniform coating with high anti-corrosion characteristic
Clean hexagon socket
Clear more than1000 hours of salt spray test
4H Go-ring gauge test after anti-corrosion coating by sampling. 5

7. 0.2%Yield strength under high temperature
Reference
■Chemical composition of KNDS4
Material
（％）
Tensile strength
（N/㎟） C Si Mn P S Ni Cr Mo Ti V
KNDS4
0.42
0.06
0.53
0.007
0.004
0.54
1.00
0.97
0.050
0.070
1,300～
　 1,400
SCM440
0.41
0.20
0.72
0.013
0.010 -
1.01
0.18
1,000～
1,200
It is to improve delayed fracture resistance and make high tensile strength characteristic possible
by reducing「Si・Mn・P・S」and increasing「Ni・Mo・Ti・V」.
■Application temperature
14.9 hex socket head cap screws keep a superior mechanical property as the following table even under high temperature environment.
0.2%Yield strength under high temperature
Temperature
300℃
400℃
（500℃）
14.9
90%
83%
64%
12.9
75% -
10.9
※The figure in the table is the percentage of
0.2 yield strength at room temperature.
※The data is for reference and it is not
recommended to be used at 500℃.
When a high temperature state continues, the relaxation that shall be considered as important may occur. For example, it is considered that when bolts are held to100 hours at 300℃ high temperature, the initial clamp force will decrease more than 25% due to the decline of yield strength. So it is essential to confirm the operating environment before using.
■Fatigue test report
　・Test Sample
　 　14.9 Hex Socket Head Cap Screws　
　 　M10 x 50L x 32S
　・Method of the test
　　Conform to JIS B 1081
add alternate load to direction of
axial until breakage and count the
number of cycle, then make S/N
curve.
fix 70% of yield strength for mean
tress and change stress amplitude.
Maximum number of cycle is by
5ｘ106（5,000,000）.
S/N Curve（14.9 Socket Head Cap Screws M10 x 50 x 32）
Stress amplitude　σa　(N/mm2)
Labo: Kishiwada Stainnless Co. Ltd.
Tester : made by Shikadzu corpration
Turbo pulsa Model EHF-EV200K A
Cycles to Failure　N
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※ Contents will be changed without notice. 6

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Yura Sansho Co.,Ltd.
[HEAD OFFICE]
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