Development of a combined technology for hardening the surface layer of steel 38Cr2MoAl

Abstract

Development of new combined strengthening technologies for treatment of steel surface layer is a topical issue. Influence of conditions of combined hardening treatment on variation of properties of the surface layer of 38Cr2MoAl steel was studied. Experimental data have shown that thickness of the hardened layer of 38Cr2MoAl steel, depending on the process conditions of combined treatment, varied in the range 0.18 to 0.69 mm with the surface hardness being 10.5-12.5 GPa. Mathematical models of the hardened layer thickness and surface hardness were obtained depending on variation of velocity of the laser beam travel and duration of nitriding of steel following the combined treatment. In their structure, the models are regression equations. These regularities have practical technological significance and ensure prediction of values of the hardened layer thickness and surface hardness. Nomograms of simultaneous influence of velocity of the laser beam travel and duration of nitriding on thickness of the hardened steel layer and surface hardness were constructed. Nomograms make it possible to determine concrete conditions of hardening processing, starting from specified thickness of the hardened layer or the surface hardness of 38Cr2MoAl steel, respectively and also to solve inverse problems. This method is suitable for hardening hard-to-reach part sectios and local contact areas.Исследовано влияние режимов упрочняющей комби-нированной обработки на изменение свойств поверх-ностного слоя конструкционной стали. Показано, что толщина упрочненного слоя составляет 0,18-0,69 мм при поверхностной твердости 10,5-12,5 ГПа. Получены математические модели и номограммы толщины упрочненного слоя и твердости стали в зависимости от технологических параметров комбинированной обра-ботки. позволяют определять конкретные условия упрочняющей обработки.