| 摘要 |
The invention relates to an object comprising at least one steel part whose composition consists of the following contents expressed by weight: 0.005-0.27 % carbon, 0.5-1.6 % manganese, 0.1-0.4 % silicon, less than 2.5 % chromium content, less than 1 % molybdenum content, optionally one or several elements selected form nickel, copper, aluminium, niobium, vanadium, titanium, boron, zirconium and nitrogen, the rest being iron and impurities of production, wherein said steel part comprises at least one area welded by a high power density beam and is characterised in that the microstructure of the welded area is constituted of 60-75 % self-tempered martensite, preferentially 60-70 % self-tempered martensite, and, in addition, of 40-30 % lower bainite. |
