求翻译：焊接材料应具有质量合格证明书。焊条质量合格证明书应包括熔敷金属的化学成分和机械性能;低氢型焊条还应包括熔敷金属的扩散氢含量。当无质量合格证明书或对质量合格证明书有疑问时,应对焊接材料进行复验。是什么意思？

The welding material should have the quality certificate of compliance. Electrode quality certificate of compliance shall include the chemical composition and mechanical properties of deposited metal; low hydrogen electrodes should also include the diffusible hydrogen content of the deposited metal.

Welding materials should have a quality certificate. Braid quality certificates of competency should include metal chymic chemical composition and mechanical properties, low hydrogen welding rod should also include in the dressing of the metal-hydrogen-content. When a quality certificate of competen

The welding material should have the quality qualified certificate.The welding rod quality qualified certificate should include the deposited metal the chemical composition and the mechanical property; The low hydrogen welding rod also should include the deposited metal the proliferation hydrogen co

Welding materials should have quality certificates. Welding quality certificate should include the chemical composition and mechanical properties of weld metal; low hydrogen type electrode deposited metal diffusion hydrogen contents should be included. When no quality certificate of compliance or ce

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