Fig. 5 Welded Integral Engine Frame of Steel Modules
The excellent durability of these bearings has been demonstrated through the overhaul inspection after 8,000-hour running of 6ADD30V for 3.1MW power plant.
3.3 Piston
The crown and the body are made of high-strength forged alloy steel and metallurgically integrated at horizontally devided surfaces by the method of diffusion-bonding. Photo 2 shows the macro structure of a diffusion-bonded piston.
The liquid-phase diffusion-bonding is applied and the bonding conditions (filler material, surface roughness, temperature, load, holding time, etc.) are determined based on a lot of fundamental tests. Though the bonded lines can be distinguished in the macro structure shown in Photo 2 due to the uncontinuity of fiber flows between a crown and a body, the microscopic inspection of bonded area indicates the complete diffusion as shown in Photo 3. It was confirmed that the fatigue strength of diffusion-bonded area is as high as 470MPa, which is almost equal to that of the mother material. A solid integral without screw connections results in light weight, which contributes to the reduction of inertia force as keeping the high strength.
