TASK 70-31-02-310-501-009 Argonarc Welding Repairs - The Procedure To Weld Nimonic 80A Alloy

DMC:V2500-00-70-31-02-08A-627A-D|Issue No:001.00|Issue Date:2013-03-20

Export Control

EAR Export Classification: Not subject to the EAR per 15 C.F.R. Chapter 1, Part 734.3(b)(3), except for the following Service Bulletins which are currently published as EAR Export Classification 9E991: SBE70-0992, SBE72-0483, SBE72-0580, SBE72-0588, SBE72-0640, SBE73-0209, SBE80-0024 and SBE80-0025.

Copyright

© IAE International Aero Engines AG (2001, 2014 - 2021) The information contained in this document is the property of © IAE International Aero Engines AG and may not be copied or used for any purpose other than that for which it is supplied without the express written authority of © IAE International Aero Engines AG. (This does not preclude use by engine and aircraft operators for normal instructional, maintenance or overhaul purposes.).

Applicability

All

Common Information

TASK 70-31-02-310-501-009 Argonarc Welding Repairs - The Procedure To Weld Nimonic 80A Alloy

General

Nimonic 80A is a nickel chromium alloy of the precipitation hardening type. It is resistant to creep and is very strong at high temperatures.

The weldability of this alloy depends on its heat treatment condition. The alloy is easily welded in the solution treated and air or water quenched condition. But Nimonic 80A is usually in the fully aged condition and not easy to weld. It also cracks easily in this condition.

Refer to TASK 70-31-02-310-501-001 for other related TASKS.

Preliminary Requirements

Pre-Conditions

NONE

Support Equipment

NONE

Consumables, Materials and Expendables

NONE

Spares

NONE

Safety Requirements

WARNING

IT IS THE RESPONSIBILITY OF THE OPERATOR TO OBTAIN AND OBSERVE THE MANUFACTURER'S MATERIAL SAFETY DATA SHEETS FOR CONSUMABLE MATERIALS. THESE CONTAIN INFORMATION SUCH AS, HAZARDOUS INGREDIENTS, PHYSICAL/CHEMICAL CHARACTERISTICS, FIRE, EXPLOSION, REACTIVITY, HEALTH HAZARD DATA, PRECAUTIONS FOR SAFE HANDLING, USE AND CONTROL MEASURES AND ALSO TO TAKE LOCAL REGULATIONS INTO CONSIDERATION.

Procedure

    1. SUBTASK 70-31-02-310-018 Preparation of the Surface

    1. Surface scale will occur if heat treatment is done in an air furnace at temperatures of more than 1292 deg F (700 deg C); for heat treatments, refer to Step. The surface finish has a green black scale at temperatures more than 1382 or 1688 deg F (750 or 920 deg C). This is as found on engine run components that operate at these higher temperatures.

    2. This oxidation scale must be removed to give a good weld. It can only be removed mechanically or with abrasive blasting.

    2. SUBTASK 70-31-02-310-019 The Procedure to Weld Nimonic 80A Alloy

    1. Tungsten inert gas welding is recommended for this material.

    2. Automatic current slope-out at the end of the weld run is necessary to prevent crater cracks.

    3. Cracks in the weld toe of repairs with large weld beads are a problem during post weld heat treatment. The procedure used to weld Nimonic 80A must be that which will cause less cracks to occur.

    3. SUBTASK 70-31-02-370-007 The Heat Treatment of Nimonic 80A

    1. Many components are not sufficiently rigid to be resistant to air, oil or water quenching. This can result in a decrease in tolerances because of distortion. Repairs to defects in the fully aged condition will not be easy.

    2. Heat treatment instructions are given in the applicable Repair. Also refer to the SPM TASK 70-31-02-310-501-001 and SPM TASK 70-31-02-310-501-004.

    3. If necessary a stress relief at 1688 deg F (920 deg C) will make welding easier.

      4. NOTE

        After the parts have been heat-treated, they must become cool in air.

        When the weld is completed heat treatment is required, the cycle to be used will be given in the Engine Manual.

        The Engine Manual will specify one of the cycles that follow:

        1. Stress relieve by heating at 1688 deg F (920 deg C) for one hour.

        1. This is used for parts which operate at temperatures of more than 1202 deg F (650 deg C) or which are not highly stressed:

        2. Stress relieve by heating at 1688 deg F (920 deg C) for one hour followed by heating at 1382 deg F (750 deg C) for four hours.

        1. This is used for parts which operate at temperatures less than 1202 deg F (650 deg C) where fully aged properties are necessary:

      3. Age at 1292 deg F (700 deg C) for 16 hours, or 1382 deg F (750 deg C) for four hours.

Requirements After Job Completion

Follow-On Conditions

NONE