The advantages of Low Pressure Carburizing in the Heat Treatment Subcontracting Business

Low Pressure Carburizing (LPC) was introduced in the 90’s in the western Europe Heat Treatment business, mainly for in-house applications where it was especially appreciated for Carburizing of transmission parts. However the success of the LPC units installed for gears Carburizing in the automotive industry has hindered the development of the process in other fields - like subcontracting business -, where its advantages deserve to be enlightened. After a brief review of the principle of the process, the interest of its classical application to transmission parts is described, underlining peculiarly the reduction of the distortion observed when LPC is associated with high pressure gas quenching. Then the less-known advantages of the LPC process, like the high accuracy and reproducibility of the results, the modeling possibility and the simulation easiness, the case-depth uniformity and the full flexibility of the units are considered, showing how they can be beneficial to subcontracting business.

Effect of strontium and solidification rate on eutectic grain structure in an Al-13 wt% Si alloy

The influence of strontium addition and solidification rate on eutectic grain structure in a near-eutectic Al-Si alloy was investigated. The characteristic temperature of eutectic nucleation (TN),minimum temperature prior to recalescence (TM),and the growth temperature (TG) during cooling were determined by quantitative thermal analysis. All characteristic temperatures were found to decrease continuously with increasing Sr content and solidification rate. Microstructural analysis also revealed that the eutectic grain size decreases with increasing Sr content and solidi fication rate. Such eutectic grain refinement is attributed to the increased actual under-cooling ahead of the liquid/solid interface during solidification.

Integration of Gas Nitrocarburising and Oxidising in a Mass Production Line for Brake Pistons

The combination of wear- and corrosion resistance is a demand to a multitude of automotive parts. Several metallic coatings as hard/soft chromium or electroless nickel have been the conventional surface protection e.g. on parts as brake pistons and shock absorber or gas spring piston rods. The Corr-I-Dur* process - a special gasnitrocarburising and oxidising technology - has a huge potential not only in substituting those coatings but also in delivering surfaces with higher quality. The benefits of the replacement of soft chromium with Corr-I-Dur and the implementation of the process in the customers production line with an annual capacity of 17 million brake pistons is described in this presentation. Starting with the demands on wear- and corrosion resistance the way of process development and the design of applicative equipment is shown. The result is a tailor-made surface solution with superior quality for deep drawn brake pistons. Two main disadvantages - outgassing of the chromium layer and reduced corrosion resistance on the inner diameter - are eliminated by the replacement with Corr-I-Dur . The process-sure achievement of enhanced corrosion resistance, uniform layer thickness, negligible distortion as well as environmental and economical advantages make Corr-I-Dur? an excellence choice for this application.

The Integration of Vacuum Brazing into Heat Treatment - A Progressive Combined Process

The continuous constructive challenge to improve the functionality and efficiency of components always results in higher demands on production engineering, against the background of the generally increasing cost pressure. In many cases, you will just succeed in producing competitive and innovative products by combining and coupling of different procedures to an independent (hybrid) technology. The use of hybrid procedures for metal joining and heat treatment of metallic materials finds more and more industrial fields of application. Modern vacuum lines with integrated pressurized gas quenching are considered high-performance and flexible means of production for brazing and heat treatment tasks as well in the turbine industry as in the mould making and tool manufacturing industry. In doing so, the heat treatment is coupled with the brazing cycle in a combined process so that the brazing temperatures and soak times are adapted to the necessary temperatures and times for solution heat treatment and austeniting. This user-oriented article describes on the one hand examples of brazing of turbine components, but above all the practical experience from the plastics processing industry, where the requirement for a high-efficient cooling of injection moulding dies gains more and more importance. The combined procedure "Vacuum Brazing and Hardening" offers plenty of possibilities to produce mould inserts with an efficient tempering system in an economic way.