High-strength stainless steel for use as material of fuel injection nozzle or needle for internal combustion engine, fuel injection nozzle made of the stainless steel

A high-strength stainless steel for use as a material of construction for a fuel injection nozzle or a fuel injection needle of an internal combustion engine, said stainless steel being an as annealed martensitic steel containing, by weight, 0.4 to 0.6% of C;

• not more than 0.5% of Si;
• not more than 0.5% of Mn;
• 8.0 to 13.0% of Cr;
• 0.1 to 2.0% of one or both of W and Mo in terms of (W/2+Mo), and wherein said stainless steel contains particulate carbide materials including a first group of carbide particles having a particle size greater than 0.2 .mu.m and a second group of carbide particles having a particle size which is smaller than the particle size of said first group of carbide particles, the number of particles in said first group of carbide particles being more than 50% of the total number of carbide particles in said steel, and wherein the hardness of said as annealed martensitic stainless steel is not higher than HB 157.

A high-strength stainless steel for use as a material of construction for a fuel injection nozzle or a fuel injection needle of an internal combustion engine, said stainless steel being an as annealed martensitic steel containing, by weight, 0.4 to 0.6% of C;

• not more than 0.5% of Si;
• not more than 0.5% of Mn;
• 8.0 to 13.0% of Cr;
• 0.1 to 2.0% of one or both of W and Mo in terms of (W/2+Mo), and wherein said stainless steel contains particulate carbide materials including a first group of carbide particles having a particle size greater than 0.2 .mu.m and a second group of carbide particles having a particle size which is smaller than the particle size of said first group of carbide particles, the number of particles in said first group of carbide particles being more than 50% of the total number of carbide particles in said steel, and wherein the hardness of said as annealed martensitic stainless steel is not higher than HB 157 and the limit swaging ratio of said as annealed martensitic stainless steel is not less than 75%.

A fuel injection nozzle for an internal combustion engine formed by forging from a high-strength as annealed martensitic stainless steel such that the fiber flow at the corner between the inner side wall surface and the inner bottom surface of the deep bore of the nozzle follows the directions of the inner side wall surface and the inner bottom surface, said steel containing, by weight, 0.4 to 0.6% of C;

• not more than 0.5% of Si;
• not more than 0.5% of Mn;
• 8.0 to 13.0% of Cr;
• 0.1 to 2.0% of one or both of W and Mo in terms of (W/2+Mo), said stainless steel having a hardness which is not less than HRC 57.

A high-strength stainless steel for use as a material of construction for a fuel injection nozzle or a fuel injection needle of an internal combustion engine, said stainless steel containing, by weight, 0.4 to 0.6% of C;

• not more than 0.5% of Si;
• not more than 0.5% of Mn;
• 8.0 to 13.0% of Cr;
• 0.1 to 2.0% of one or both of W and Mo in terms of (W/2+Mo), and wherein said stainless steel contains particulate carbide materials including a first group of carbide particles having a particle size greater than 0.2 .mu.m and a second group of carbide particles having a particle size which is smaller than the particle size of said first group of carbide particles, the number of said first group of carbide particles being more than 50% of the total number of carbide particles in said steel.