July 20, 2015

Chinese and Russian Submarine Pressure Hull Strengths

Yield Strength (YS = yield strength or proof stress)
YS US    UK FranceGermanyChinaRussiaJapanAustraliaSweden
550MPaHY80Q1N1.3964* 1)
690MPaHY100Q2NAB-2* 2)

AK- ??

* 3)

* 1) steel of 550MPa and NS56 is equivalent to HY80 grade steel.
* 2) steel of 690MPa and NS70 is equivalent to HY100 grade steel.
* 3) steel 1078MPa and NS110 is equivalent to the HY156 grade steel.
* 4) Ti80 Titanium alloy under development 880MPa equivalent to NS90 or HY128 steel - source.

The Table is from towards the end of Japanese Document "High-tensile steel Summary of national submarine" or Summary of High Tensile Steel for Submarines by Country 2013 http://seesaawiki.jp/w/doramarine/ .


The document below which provides a comprehensive summary of some nuclear and conventional submarine pressure hull steel (and some Titanium) strengths. This is for at least 11 major submarine producing countries. The document is attributed to a vast number of open sources. 

The higher the yield (stronger) the steel alloy or Titanium alloy in a submarines pressure hull the deeper it can dive in operations. As well as alloy strength other factors also influence diving depth including:

- supports for the the pressure hull

- compartments or multiple pressure hulls, and

- strength of the welds used to join sections of the pressure hull.

It is not possible to verify the accuracy of most of the figures. Commenters who know more are invited to supply corrections.

Please connect with Submarine Matters "Previous Use of Titanium in Russian Submarines" July 14, 2015 http://gentleseas.blogspot.com.au/2015/07/previous-use-of-titanium-in-russian.html

Document Link

Click http://seesaawiki.jp/w/doramarine/  - document will appear to be mainly in Japanese - if you have Windows right click mouse - then click Translate to English (or Russian or Chinese etc). 

The English translation is not great - which is why I have provided a summary of some Chinese and Russian pressure hull strengths below.

Document Name and Year

"High-tensile steel Summary of national submarine" or Summary of High Tensile Steel for Submarines by Country 2013.

Summary of Chinese and Russian High Tensile Alloys Pressure Hulls by Submarine Class

Below are some of the details for China and Russia. Many more details are in the Document text.

Utilising converters 
    Chinese Submarine pressure hulls 
Type 093 "Shang" class SSN (2 or 3 active) and Type 094 "Jin" class SSBN (4 active) "980"  steel which has a strength between 784MPa and 802MPa = average of 793MPa = NS81 = HY115 

Type 039 "Song" class SSK (13 active) and possibly Type 039A "Yuan" class SSK (13 active, 7 building) 921A steel: strength 590MPa = NS60 = HY86 

Chinese GJB944-90 Titanium alloy (TA5-A) strength 588MPa = NS60 = HY85 seems to be the equivalent to Russian 48-OT3 Titanium alloy.

[There is an interesting reference on Chinese Titanium alloy research for pressure hulls. The reference is  “Research progress in titanium alloys for naval ships in China” by YANG Ying-li, et al., The Chinese Journal of Nonferrous Metals, 2010, vol. 20, special 1, pages 1002 to 1006. http://www.ysxbcn.com/down/upfile/soft/20101012/215-p1002-6-033.pdf
This concerns “Ti80” titanium alloy for submarine pressure hulls. It has been developed by Shanghai Iron and Steel Research Institute which appears to have connections with and China Iron and Steel Research Institute Group (CISRI) and Baosteel Group Shanghai No.5 Iron & Steel Co. Ltd

The composition of Ti80 is Ti-6Al-3Nb-2Zr-1Mo with properties of high toughness, weldability, corrosion resistant, good low-cycle fatigue. Yield strength of Ti80 is 880MPa = NS90  = HY128. While Ti80’s while proof strength is 785MPa.

Stages in R&D on marine Titanium in China which may potentially be used in pressure hulls  are:

1962-1987  Initial stage: TA5, believed to be an imitation of Russian or US Titanium alloy.
1987-2009  Independent innovation stage: Various Titanium alloys developed including Ti80.
2008-present  Industrial research and promotion stage.

Summary of “Research progress in titanium alloys for naval ships in China” Conclusion: Chinese development of Titanium for marine uses is mature in research institutes but still needs further and systematic testing under conflicting performance parameters. Much more work needs to be done before Titanium alloys can be used in Chinese submarine pressure hulls.] 

Russian submarine pressure hulls

Akula class SSGN-SSN commissioned 1991 onwards, ten still active , may use AK-33 steel alloy = 979MPa = NS100 = HY142

Yasen-Severodvinsk class SSGN (or SSN) one commissioned 2013, four being built, may also used a low magnetic steel alloy - perhaps a development of AK-33. See Russian website.

Lada class SSK one commissioned 2010 uses "AB-2 "steel: strength 588-686MPa = NS60 - NS70 = HY85 = HY100  (thickness in mm?)

Oscar I, II and III SSGN commissioned 1980 onwards, five still active, may use AK-33 steel alloy.

Sierra class SSN one launched 1983, four built, perhaps two still active - uses Titanium alloy hull - average strength 690MPa = NS70 = HY100 

Victor class SSN commissioned from 1967 - early Victors (classes I and IIs) may have used "AK-29" steel: strength 784MPa = NS80 = HY114. Eight Victor IIIs still active - may use "AK-33" = 979MPa = NS100 = HY142.

November class SSN in commission 1959-1990 used "K-25" low magnetic steel 588MPa = NS60 = HY85

I'll summarise other parts of the document in the future.



Anonymous said...

Hi Pete

I found information on Ti80, titanium alloy for deep submarine pressure hull material, developed by Shanghai Iron and Steel Research Institute [1].

Composition of Ti80: Ti-6Al-3Nb-2Zr-1Mo
Properties of Ti80: high toughness, weldability, corrosion resistant, good low-cycle fatigue etc.
Mechanical strength of Ti80: yield strength 880MPa, 0.2% proof strength 785MPa.

Brief history of R&D of the marine titanium in China [1]
1962-1987 Initial stage: TA5, which is imitation of USSR or USA titanium
1987-2009 Independent innovation stage: Various titanium alloys were developed including Ti80.
2008-present Industrial research and promotion stage

Conclusion of this paper [1].
Although Chinese ship system has been formed with titanium, titanium alloy production of marine, construction technology and application timing bulk ship products has been basically mature. But the ship timber to put forward conflicting performance requirements, the China Ship titanium is far from the overall design institutes, research materials and semi-preparation unit, effective coordination part shaping and application performance research units, factory ship between cooperation mechanism, resulting in the current application level is still scattered, sporadic trial status, but in some special high-speed boats, boat construction applications. In addition, ship designers and manufacturers of titanium alloys is not very comprehensive understanding of its application in the ship, there are still some concerns, ship titanium equipment manufacturing site processing applications supporting capacity is very weak, and more no master key technologies. Therefore, in order to get a large number of titanium used in the ship, there are a lot of work to do. This requires personnel to help designers in the product design process more from life, technical performance considerations in the selection, make titanium products in the shipment practice gradually be promoted and improved.

[1] “Research progress in titanium alloys for naval ships in China” by YANG Ying-li, et al., The Chinese Journal of Nonferrous Metals, 2010, vol.20, special 1, pages 1002-06. http://www.ysxbcn.com/down/upfile/soft/20101012/215-p1002-6-033.pdf


Anonymous said...

Weldox seem to be as high as 1300 and a weight to strength ratio equal to many aluminum alloys.
Could be useful, right?


Anonymous said...

Oh, sorry, forgot the link.

Peter Coates said...

Hi S [at July 21, 2015 at 5:14 AM]

Thanks very much for the Ti80 information. I have incorporated into the text and the Table.

Deep diving Chinese SSNs (using Ti80 or similar) might be something to watch for within the next 10 years.



Peter Coates said...

Hi /TTAero

Thanks for http://www.ssab.com/en/Brands/Weldox/Products/Weldox-1300/

I'm no metal expert but Weldox-1300 may be viable if it can be fabricated into very large circular sections for submarines, can be welded and most importantly can contract and expand many times without cracking.

The generally shallow operating area for Swedish submarines in the Baltic may reduce interest in alloys for very deep diving.



Anonymous said...

Hi Pete

Love it


Anonymous said...

Hi Pete

Oscar I,II and,III adopt AK-33 steel, but Yasen-class submarine adopts unknown low magnetic steel [1]. This reference shows detail information on Project 885 "Ash"-Submarine "Severodvinsk".

[1] Submarine Project 885 "Ash", see Description of construction.


Peter Coates said...

Hi S [at July 25, 2015 at 10:51 AM]

Thanks for info. I have placed it in the text.



Aiden Smith said...

That really good news for the industry such kind of research and development is necessary for industrial growth.