EFFECT OF HOT-DIP GALVANISING ON THE MECHANICAL PROPERTIES OF STRUCTURAL STEEL AND BRITTLE FRACTURE OF PUNCHED COMPONENTS

EINFLUSS DES FEUERVERZINKENS AUF DIE MECHANISCHEN EIGENSCHAFTEN VON BAUSTAHL UND DAS SPROEDBRUCHVERHALTEN GESTANZTER TEILE

THE EFFECT OF HOT GALVANIZING, CARRIED OUT BY THE NORMAL METHOD, ON THE MECHANICAL PROPERTIES OF THE STEELS RST 37-2 AND ST 52-3 WAS EXAMINED. A SIGNIFICANT INCREASE IN THE ELONGATION LIMIT BEHAVIOUR AS WELL AS A TECHNICALLY INSIGNIFICANT REDUCTION IN THE FRACTURE-ON-DEFORMATION VALUES WAS THUS FOUND JUST AFTER THE GALVANIZING OF TENSILE SAMPLES WHICH WERE NOT PREFORMED. THE EFFECTS OF DIFFERENT TYPES OF TREATMENT ON THE PROPERTIES OF PRE-ELONGATED SAMPLES ARE GREATER. IN THIS CASE, STRAIN AGEING IS INVOLVED - INDICATED BY THE MARKED INCREASE IN THE ELONGATION LIMIT BEHAVIOUR - WHICH HOWEVER IS AGAIN SOMEWHAT REDUCED BY GALVANIZING DUE TO THE TEMPORARY TEMPERING EFFECT. THE EFFECT OF THE AGEING PROCESS ON THE FRACTURE-ON-DEFORMATION VALUES IS VARIABLE. CORRESPONDING TO IDEAS REGARDING THE EFFECT OF THE FLOW LIMIT AND THE SLIT FRACTURE STRESS ON THE TRANSITION FROM VISCOUS TO BRITTLE FRACTURE THE TRANSITION TEMPERATURES OF GALVANIZED NOTCH IMPACT SAMPLES, WITHIN EXPERIMENTAL LIMITS, ARE OBVIOUSLY COMPARABLE WITH THOSE OF ARTIFICIALLY AGED SAMPLES. THE BRITTLE FRACTURE RESISTANCE OF GALVANIZED SAMPLES LIES WITHIN THE RANGE OF RESULTS OF ARTIFICIALLY AGED PARTS USED FOR COMPARISON. NO TECHNICALLY SIGNIFICANT DELETERIOUS EFFECT OF HOT GALVANISING ON THE RESISTANCE TO BRITTLE FRACTURE OF CONSTRUCTION COMPONENTS COULD BE FOUND IF THE STRAIN AGED MATERIAL STATE AFTER A PERIOD OF LONGER USE IS TAKEN AS A REFERENCE BASIS.