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SUS 630 Precipitation Hardening Stainless Steel – JIS G4303

What is SUS630 Steels? Grade 630 are stainless steels categorized as martensitic, but additionally this grade is precipitation hardened to attain robust mechanical properties. These steel acquire high tensile strength and resistance to indentation just after heat treatment. Resistance to corrosion and heat is comparable equivalent to that of grade 304 steels. This grade is also named as grade 17-4PH.

One of the main advantages of this grade is that it is marketed in conditions such as solution treated, at which they can be swiftly age-hardened (to gain high strength) and machined. The treatment to aging of grade 630 is implemented at low temperatures, to prevent considerable distortion. Hence this grade is employed for applications for instance the production of shafts (extended) after heat treatment that do not need re-straightening.

What is JIS G4303? It is a material standard produced by Japanese Standards Association on standardization and Specification of hot worked stainless steel bars with diverse forms and shapes.

Why SUS 630 called Grade 630 Stainless Steel? When a material grade is designated as SUS grade steel, it refers it is a Japanese name. SUS 630 is also called as Grade 630 steel in various international standards. It is explained in JIS G4303. Both grades have the same chemical composition and mechanical properties.

SUS 630 grade has got a high resistance to stainless steel as compare to SUS 304 Stainless Steel Austenite Grades. They show advance resistance to stress corrosion cracking, if aged at five hundred and fifty degree Celsius or more. But, SUS 630 steels offer reduced resistant to Condition A solution treated, and therefore these steels, also with significant hardness, should not be utilized in this condition A.

Available Forms in Market: Following are the available forms of SUS630 steels in the international market:

  • Bar Finish
  • Plates
  • Seamless Pipe
  • Welded Pipe
  • Pipe Fittings
  • Wire
  • Sheet
  • Forging

Dimensional Characteristics of SUS 630 Steels: Different suppliers supply with different specification ranges as per the demanded form. However commonly the thickness for this SUS 630 material as obtained by data in the market which starts from 1 mm to 30 mm. However the width of this material ranges to 700 mm to 1500 mm.

The Chemical Composition of SUS630 Steels:  The chemical composition of this grade is as under:

  • Maximum percentage of Carbon (C) is 0.07 percent.
  • Chromium percentage ranges from 15 to 17%.
  • Maximum percentage of Manganese (Mn) is 1.0 percent.
  • Maximum percentage of Phosphorous (P) is 0.04 percent.
  • Maximum percentage of Sulphur (S) is 0.03 percent.
  • Maximum percentage of Silicon (Si) is 1.0 percent.
  • Minimum percentage of Nickel (Ni) is 0 percent and maximum is 5.0 percent.
  • Copper (Cu) ranges from 3 to 5 %.
  • Niobium (Nb) ranges from 0.15 to 0.45%

Remaining is iron (Fe) percentage and with few negligible impurities.

Mechanical Properties of SUS630 Steels: Following are some of the mechanical properties of 420 steels:

  • The tensile strength of the 630 alloy steel is expressed in Newton per millimeters and it must be at-least 930  N/mm2 (MPa) and maximum is 1310 N/mm2 (MPa).
  • The elongation property of SUS630 steel varies with the thickness and ranges from 40 to 50 %.
  • The minimum hardness range for this type is 277 HB.

Equivalent Material Grades in Other International Standards:

  • Equivalent grade of this type in American Standard is Grade 630 steel.
  • In DIN standard, the equivalent material is referred as 1.4542 type steel.
  • In UNS standard, the equivalent material is referred as S17400 type steel.

 Applications of SUS630 Stainless Steels: Applications are as under:

  • Parts of Engine
  • Gears and Valves
  • Dies of plastic moulds
  • Waste bucket of Nuclear plant
  • Production equipment in aerospace such as turbine
  • Handling equipment used in offshore platform
  • Instruments in paper industry

Suppliers of SUS 630 Steel: Suppliers are also listed below:

  • Supplier LonghaiSteel Inc bearing contact number 86-816-3307163.
  • Supplier China United Iron And Steel Limited bearing contact number 0086-13598879167.The supplier address is No.1312 Gelin International Building, Henan Province of China.


Waqas Imam is an Industrial Engineer, Certified Lead Auditor, Material Consultant and Blog Writer.

  1. Tracy says:

    I M looking for
    AISI 17-4PH
    OD 14mm
    ID 9mm
    Seamless Pipe
    Monthly Usage : 3000 kgs
    Application : Medical

  2. Jiwoong, Choe says:

    I am looking for SUS630 O.D 12mm round bar, or O.D 12mm I.D 8mm or less pipe.
    If you are available for those products, please send quotation of it.
    Thank you.

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