Super Alloy HPA 50 (UNS S20910)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Other Designations
Fabrication and Heat Treatment
     Machinability
     Forming
     Forging
     Welding
     Annealing
     Hardening
Applications

Introduction

Super alloys, also referred to as high performance alloys, perform excellently in high temperature environments. They are widely used in many industrial sectors.

Super Alloy HPA 50 is an austenitic, nitrogen strengthened steel alloy. It has corrosion resistance that is similar to grade 316 stainless but possesses greater strength. It can be readily fabricated and remains non-magnetic even after rigorous forming operations. It has excellent yield strength.

The following sections will discuss in detail about super alloy HPA 50.

Chemical Composition

The chemical composition of super alloy HPA 50 is outlined in the following table.

Element Content (%)
Chromium, Cr 20.5 - 23.5
Nickel, Ni 11.5 - 13.5
Manganese, Mn 4-6
Molybdenum, Mo 1.5 - 3
Silicon, Si 1 max
Nitrogen, N 0.2 - 0.4
Vanadium, V 0.1 - 0.3
Niobium, Nb 0.1 - 0.3
Carbon, C 0.06 max
Phosphorus, P 0.04 max
Sulfur, S 0.03 max
Iron, Fe Remainder

Physical Properties

The physical properties of super alloy HPA 50 are tabulated below.

Properties Metric Imperial
Density 7.7 g/cm3 0.28 lb/in3

Other Designations

Equivalent materials to super alloy HPA 50 are listed below:

ASTM A193 (B8R, B8RA) ASTM A240 (XM-19) ASTM A249 (XM-19) ASTM A312 (XM-19) ASTM A403 (XM-19)
ASTM A182 (XM-19) ASTM A194 (B8R, B8RA) ASTM A269 (XM-19) ASTM A336 (XM-19) ASTM A412 (XM-19)
ASTM A479 (XM-19) ASTM A580 (XM-19) ASTM A813 (TP XM-19) ASTM A276 DIN 1.3964

Fabrication and Heat Treatment

Machinability

Super alloy HPA 50 can be machined using the common processes. Slow speeds, generous quantity of resulfurized lubricant and constant feeds are essential for machining this alloy. The speeds and feeds can match that of stainless grades 316 or 317. the chips tend be tough and stringy and it is recommended that curlers or breakers are used.

Forming

Super alloy HPA 50 can be formed using any of the conventional methods. The springback tends to be greater for this alloy than with standard austenitics and hence care should be to provide appropriate forming forces. It is recommended that process annealing be performed to remove stresses caused by this alloys' high work hardening rate. In case of intermediate annealing, this alloy has to be heated to 1065°C (1950°F).

Forging

Forging of super alloy HPA 50 can be performed by heating to 1093°C (2000°F), soaking to equalize, and then heating to 1176°C (2150°F). This process should be followed by annealing so as to regain optimum corrosion resistance.

Welding

Welding of super alloy HPA 50 can be performed using all the traditional welding methods such as gas tungsten arc, gas metal arc and submerged arc methods. It is recommended that a filler matching the higher alloy material should be selected to provide optimum results. Pre-heating is not required with this material.

Annealing

Annealing of this material can be performed by soaking at 1037-1121°C (1900-2050°F) and then rapidly quenching in air or water.

Hardening

Super alloy HPA 50 hardens only by cold work.

Applications

Super alloy HPA 50 is used in the following application areas:

  • Super alloy HPA 50 is mainly used in applications requiring high strength and corrosion resistance such as marine hardware, boat shafting, fasteners, valves, and pumps.

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