zielsicher Englisch, Metalltechnik, Schulbuch

Look at these tools – the spanner, the hammer, the chisel and the pipe wrench. Work with a partner and try to answer these questions. Use the internet for help. What do these tools have in common? They have a high amount of hardness. How do they get such resistant properties? through heat treatment Which process is it necessary to apply? annealing, heating or diffusion-processes Read the text and the overview. Mark the words you don’t understand. Heat treatment is a technique used to generate particular material properties of work pieces and tools, mostly metals, through changes in temperature. Heat treatment techniques work by thermal and thermochemical impact, with the goal of reaching optimum performance characteristics. The main difference between the various heat treatment techniques is that some transform the microstructure of the work pieces completely to the core, whereas others only transform the surface. The first group includes annealing and hardening. The second technique is a diffusion process – e. g. case hardening or nitriding. Heat Treatment Thermal processes Thermochemical processes annealing processes hardening processes diffusion processes • normalising • soft-annealing • stress relief annealing • recrystallisation annealing • coarse-grain annealing • hardening • tempering • surface hardening • carburization • case hardening • nitriding 01 A2–B1 02 A2–B1 Heat treatment Robert and his colleague Simon are mechanics. They are talking about material properties of tools. Tools they use very often are spanners – in different sizes. What kind of material property do you think of when holding a spanner in your hands? 100 Unit 19 Nur zu Prüfzwecken – Eigentum des Verlags öbv