Chinese, Russian & Western Submarine Pressure Hull Strengths

YS = Yield Strength or proof stress. HY = High Yield

YS	US	UK	France	Germany	China	Russia and India	Japan	Australia	Sweden
550MPa	HY80	Q1N		1.3964		India DMR- 292 #	* 1) NS56
590MPa			60 HLES		921A TA5-A	AK- 2548 -OT3
630MPa				1.3974
690MPa	HY 100	Q2N				AB-2	* 2) NS70
700MPa			80 HLES					BIS 812 EMA	Wel  dox 700
785MPa					980	AK-29	NS80
890MPa	HY 130		100 HLES		*4) Ti80	AB-3?	NS90		Wel dox 900
980MPa						AK-33
1075MPa						AK- ??
1178MPa	HY 156						* 3) NS 110

# on India see GhalibKabir's comment (Comment section below) of December 31, 2018. Indian steelmill made pressure hull steel was originally developed from Russian steel.

* 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/ .

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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 

• The Japanese NS measure (kgf/mm2) to US (ksi = 1,000 psi) and vice versa http://www.endmemo.com/sconvert/kgf_mm2ksi.php

• psi x 1000 = HY converted to MPa and vice versa http://www.convertunits.com/from/psi/to/MPa . 

    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.

Pete