Method for manufacturing gas turbine blade, and gas turbine blade

1. A method for manufacturing a gas turbine blade, comprising the steps of:

producing a gas turbine blade having a cooling pass inside thereof; and

partially coating an inner surface of the cooling pass with Al;

wherein the step of partially coating an inner surface of the cooling pass with Al comprising:

a sample-substrates-preparing step of preparing a sample substrate A which comprises same composition of an actual machine of the gas turbine blade and preparing a sample substrate B which is applied an Al coating to the sample substrate A;

a first step of specifying a temperature range which satisfies both of oxidation resistance and fatigue strength based on an examination result of a temperature dependency of each of the oxidation resistance and fatigue strength of each of the sample substrates A and B, and further specifying the temperature distribution of the inner surface of the cooling pass based on an examination result or result of a numerical analysis;

a second step of setting an Al-coating-applying portion of the inner surface of the cooling pass as the temperature range specified at the first step; and

a third step of applying Al coating only into the set Al-coating-applying portion.

2. The method according to claim 1 ,

wherein the third step further comprising the steps of:

filling the cooling path with Al pack powder which comprises Al powder or Al alloy powder and powder of an adsorbable metal oxide;

heating the turbine blade in argon gas at 700 to 1000° C.; and

cooling the turbine blade and removing the adsorbable metal oxide in the cooling path.

3. The method according to claim 2 ,

wherein the adsorbable metal oxide is filled into an Al-coating-unapplying portion of the inner surface of the cooling pass, which is not the Al-coating-applying portion.

4. The method according to claim 2 ,

wherein the metal oxide is any one selected from the group consisting of Al 2 O 3 , MgO and CaO.