630 Stainless Steel Bar

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Steel Type – Precipitation Hardening

It is a martensitic precipitation hardening stainless steel with high strength and hardness. The mechanical properties are obtained by a solution treatment (Cond. A) that brings the Cu in solution in the Austenitic matrix followed by a rapid cooling obtaining a super-saturated Cu martensitic structure. A re-heating ( ageing ) at t° = 480°C gives a maximum Hardness and resistance Rm, with low Kv impact, due to a precipitation of Cu –rich phase. Ageing at t°= 620°C results in a higher Kv impact, with a reduction of Rp0,2 and Rm, due to a progressive softening of Martensite and the formation of both Cu-globules with loss of coherence within the matrix, and stable Austenite. It is important to know that the transformation of Austenite to Martensite is completed below 30°C and the formation of stable Austenite during aging can start to appear at 550°. This strongly depends on the (Cr/Ni) equivalent balance that, besides, influences the amount of Ferrite in the matrix.

Designations

VALBRUNA
V174
AISI
630
W.N.
1.4542
UNS
S17400
EN
X5CrNiCuNb16-4

Specifications

ASTM
A564
EN
10088-3

Chemical Composition

Min.
Value %
C
-
Mn
-
Si
-
S
-
P
-
Ni
3%
Cr
15%
Mo
-
Cu
3%
Ta+Nb
0.15%
Nb
5*C
Max.
Value %
C
0.07%
Mn
1%
Si
0.7%
S
0.03%
P
0.04%
Ni
5%
Cr
17%
Mo
0.5%
Cu
5%
Ta+Nb
0.45%
Nb
0.45%

Applications

It can be used in different kind of application as valves, chemical and power productions components, engine parts, fitting, fasteners, shafts and pumps shafts and parts of oil & gas plants.

Machinability

Machinability is good in both the solution-treated (cond.A) and precipitation hardening conditions, considering that this property improves when hardness decreases. A certain amount of dimensional changes, in terms of contraction, happens after the aging of parts: these dimensional variations should be evaluated.

Mechanical Properties

CONDITION
Solution Annealed
SUBTYPE
AT
Rm [N/mm²]
1200 max.
HBW
360 max.
Rp0.2% [N/mm²]
-
E4d [%]
-
CONDITION
Solution Annealed-Aged
SUBTYPE
H900
Rm [N/mm²]
1310 min.
HBW
388 min.
Rp0.2% [N/mm²]
1170 min.
E4d [%]
10 min.
CONDITION
Solution Annealed-Aged
SUBTYPE
H925
Rm [N/mm²]
1170 min.
HBW
375 min.
Rp0.2% [N/mm²]
1070 min.
E4d [%]
10 min.
CONDITION
Solution Annealed-Aged
SUBTYPE
H1025 (P1070)
Rm [N/mm²]
1070 min.
HBW
331 min.
Rp0.2% [N/mm²]
1000 min.
E4d [%]
12 min.
CONDITION
Solution Annealed-Aged
SUBTYPE
H1075
Rm [N/mm²]
1000 min.
HBW
311 min.
Rp0.2% [N/mm²]
860 min.
E4d [%]
13 min.
CONDITION
Solution Annealed-Aged
SUBTYPE
H1100 (P960)
Rm [N/mm²]
965 min.
HBW
302 min.
Rp0.2% [N/mm²]
795 min.
E4d [%]
14 min.
CONDITION
Solution Annealed-Aged
SUBTYPE
H1150 (P930)
Rm [N/mm²]
930 min.
HBW
277 min.
Rp0.2% [N/mm²]
725 min.
E4d [%]
16 min.
CONDITION
Solution Annealed-Double Aged
SUBTYPE
H1150M (P800)
Rm [N/mm²]
795 min.
HBW
255 min.
Rp0.2% [N/mm²]
520 min.
E4d [%]
18 min.
CONDITION
Solution Annealed-Double Aged
SUBTYPE
H1150D
Rm [N/mm²]
860 min.
HBW
255 - 311
Rp0.2% [N/mm²]
725 min.
E4d [%]
16 min.

Physical Properties

Density
SI / Metric Units
7.8 kg/dm³
US / BS Imperial Units
0.282 lb/in³
Specific Thermal Capacity 20° C
SI / Metric Units
500 J/(kg·K)
US / BS Imperial Units
0.119 Btu/lb°F
Thermal conductivity 20° C
SI / Metric Units
16 W/(m·K)
US / BS Imperial Units
110.936 Btu in/ ft² h °F
Thermal expansion 20° - 100° C
SI / Metric Units
10.9 (10⁻⁶/K)
US / BS Imperial Units
6.056 (10⁻⁶/°F)
Electrical Resistivity 20° C
SI / Metric Units
0.71 Ω·mm²/m
US / BS Imperial Units
27.953 μΩin
Modulus of Elasticity 20° C
SI / Metric Units
200 GPa
US / BS Imperial Units
29007.548 ksi

Heat Treatment

Solution Annealed
Condition
AT
Minimum temperature °C
1025
Maximum temperature °C
1050
Cooling
Air
Solution Annealed-Aged
Condition
H900
Minimum temperature °C
480
Maximum temperature °C
-
Cooling
Air
Solution Annealed-Aged
Condition
H925
Minimum temperature °C
495
Maximum temperature °C
-
Cooling
Air
Solution Annealed-Aged
Condition
H1025 (P1070)
Minimum temperature °C
550
Maximum temperature °C
-
Cooling
Air
Solution Annealed-Aged
Condition
H1075
Minimum temperature °C
580
Maximum temperature °C
-
Cooling
Air
Solution Annealed-Aged
Condition
H1100 (P960)
Minimum temperature °C
595
Maximum temperature °C
-
Cooling
Air
Solution Annealed-Aged
Condition
H1150 (P930)
Minimum temperature °C
620
Maximum temperature °C
-
Cooling
Air
Solution Annealed-Double Aged
Condition
H1150M (P800)
Minimum temperature °C
760 + 620
Maximum temperature °C
-
Cooling
Air
Solution Annealed-Double Aged
Condition
H1150D
Minimum temperature °C
620 + 620
Maximum temperature °C
-
Cooling
Air

Hot Working

Description of condition
Forging / Hot Rolling
Condition
900
Minimum temperature °C
1150
Maximum temperature °C
Air
Cooling
Forging / Hot Rolling

Weldability

This grade has a good weldability and doesn’t normally need preheating, but welding design should be well evaluated in order to avoid situations prone to generate stress. In short, small sections could be welded in the solution treatment condition followed by an aging; large or heavy sections require a high temperature aging or overaging obviously followed by a new solution treatment (cond. A) and an aging.

Corrosion Resistance

This grade has the same general resistance corrosion as 304 but better than the group of standard martensitic 400 series. However, solution treatment (cond. A) without aging should be avoided. For maximum resistance to Chloride stress corrosion cracking, it should be aged at a higher temperature, not less than 550-580°C. In Sulfide aggressive environments, age at 620° C or overage. The same choice should be done in the case of situations or environments prone to cause H-embrittlement. It should also be noted that for this grade, as for every kind of stainless steel, surfaces should be free of contaminants and scale, and passivated for optimum resistance corrosion.

Cold Working

This grade has a limited cold deforming capacity in the annealed condition (cond.A) due to untempered Martensite. More severe cold working requires aging at the highest temperature or overaging. For restoring or increasing mechanical properties, such as Tensile Rm, a new solution treatment (cond.A) followed by a suitable aging temperature should be carried out.

Hot Working

Ingots or large forgings require a suitable preheating in order to avoid thermal cracking. Avoid overheating and improper cooling. Large forging bars should be equalized at 1030 -1040°C in the heating furnace prior to cooling. Both small or large forgings, rolled rings or bars must be cooled under 30°C after solution treatment (cond. A) in order to complete the transformation of martensite, obtaining both a good structure and mechanical properties after aging. It is useful to point out that a certain amount of Ferrite could be in the V174 structure.

Melting Practices

Argon Oxygen Decarburization, AOD + ESR