Material Corrosion and Material Degradation by Radiation

DOE-HDBK-1132-99

Welding process restrictions may be needed for certain materials. For example,

welded fabrications are not normally used for cast irons due to their hardenability

and tendency to crack during welding. Other examples include quenched and

tempered alloy steels, which may need restrictive heat input limitations during

welding to maintain adequate strength.

Some welding processes may not be suitable for certain materials or material

thicknesses. An example is restriction of the gas metal arc welding process used

on thin materials when the short circuit mode of transfer is used. This limitation

reduces the possibility of lack of fusion defects caused by this low heat, input

welding process.

When welding is required on austenitic stainless steels, it may be advisable to

use only the low-carbon grades (e.g., 304L, 316L, etc.) or controlled heat input

weld processes to reduce susceptibility to intergranular-corrosion or

intergranular-stress-corrosion cracking.

Certain contaminants on materials may be harmful during welding and should be

controlled. Zinc and other low-melting-point metals embrittle austenitic stainless

steel and nickel-based alloys during welding. Welding of zinc-coated materials

to austenitic stainless steels or nickel-based alloys will lead to weld-metal or

base-metal cracking. This problem may occur even if the zinc coating has been

mechanically removed. Use of an uncoated transition piece is recommended.

Special welding techniques to provide oxide-free welds should be considered for

materials in tritium service. The technique may include special cleaning prior to

and after welding and adhering to special welding parameters.

It is a good practice to use qualified welding procedures and qualified welding

personnel for all welded fabrication. Additionally, it is good practice to use

written procedures to perform other special processes, such as heat treating,

forming, bending, nondestructive examinations, and leak testing.

Material Corrosion and Material Degradation by Radiation . Corrosion and radiation

5.4

degradation of materials can be a serious problem. Mitigation of corrosion and material

susceptibility to radiation degradation is an important design consideration. Factors to

be considered for the control of corrosion and radiation degradation are as follows:

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