Method for manufacturing a steel part, including the addition of a molten metal to a supporting part, and part thus obtained

Method of manufacturing a final steel part comprising a steel support part and at least one portion formed by a method for adding a filler metal in the form of molten metal onto a portion of the surface of the support part, thus forming a heat affected zone (HAZ) on the steel support part and a molten zone between the HAZ and the portion formed by adding the molten metal, wherein:

• the support part is made of a chromium steel with a microstructure which is 70-100% martensitic, in the quenched or tempered state, while the remainder of the microstructure is composed of ferrite, austenite and carbides and/or carbonitrides, the composition of which, in percentages by weight, consists of:
• 0.01%≤C≤1.5%;
• 0.01%≤N≤0.2%;
• 0.2%≤Mn≤1.2%;
• 0.2≤Si≤1.2%;
• traces≤Al≤0.1%;
• traces≤S+P≤0.05%;
• 5.0%≤Cr≤16.5%;
• traces≤Ni≤3.5%;
• traces≤Mo+W≤2.0%;
• traces≤Cu≤3.0%;
• traces≤Ti+Nb+Zr+V+Ta≤2%;
• traces≤Co≤0.5%;
• traces≤Sn+Pb≤0.04%;
• traces≤B≤0.01%;
• the remainder being iron and impurities resulting from the preparation;
• and meets the conditions:
• A=% Mn+% Ni+% Cu+30*(% C+% N)−3*(% Ti+% Nb)≥1.5%
• B=% Cr+% Mo+5*% V+% W+% Si+% Al≥9% ;
• wherein the composition of the filler metal before its use consists of:
• 0.01%≤C≤0.1%;
• 0.01%≤N≤0.2%;
• 0.2%≤Mn≤2.0%;
• 0.2≤Si≤1.2%;
• 15.0%≤Cr≤19.0%;
• 6.0%≤Ni≤13.0%;
• traces≤Mo+W≤3.0%;
• traces≤Cu≤3.0%;
• traces≤Co≤0.5%;
• traces≤B≤0.01%;
• traces≤S+P≤0.05%;
• traces≤Ti+Nb+Zr+V+Ta≤2%;
• traces≤Sn+Pb≤0.04%;
• the remainder being iron and impurities resulting from the preparation;
• wherein the hardness of the HAZ is not less than 20% more than that of the remaining parts of the support part, and wherein the martensite content of the HAZ is greater than or equal to equal to 70%;
• and wherein the molten zone has a dilution ratio (% Ni (molten metal)−% Ni (metal support))/(% Ni (filler metal)−% Ni (metal support)) from 50 to 95% by weight.