16mn seamless insufficient hardness causes and preventive measures

Resulting in insufficient hardness after quenching 16mn seamless causes and solutions

16mn purpose is to enable seamless quenching supercooled austenite martensite or bainite conducted to obtain martensite or bainite, and then with a different tempering temperatures to dramatically improve 16mn seamless rigidity, hardness, wear resistance, fatigue strength and toughness, so as to meet a variety of machine parts and tools of different requirements. You can also meet some special physical and chemical properties of ferromagnetic special steel, corrosion resistance by quenching.

16mn seamless insufficient hardness causes and preventive measures are as follows:

1, the quenching temperature is too low, mainly due to improper temperature setting process, temperature control system errors, installed into the cooling tank furnace or other causes of improper methods, should be amended process temperature maintenance check temperature control system, when installed furnace, 16mn no slotted tube placed evenly spaced reasonably dispersed into the slot, prohibit or bundles piled into the slot cooling.

2, the quenching temperature is too high, which is caused by improper set temperature or temperature control system error, it should amend the process temperature, and maintenance check the temperature control system.

3, over-tempering, which is caused by the tempering temperature is set too high, the temperature control system error or malfunction of the furnace when the furnace temperature is too high, the process temperature should be corrected and maintenance check temperature control system, set the oven temperature no higher than loading.

4, improper cooling, the reason is the pre-cooling time is too long, the inappropriate choice of the cooling medium, 16mn seamless steel pipe quenching medium high temperature gradually increase while cooling performance falls, poor mixing or out temperature is too high, measures: baked into the ducts to be fast; grasp the cooling characteristics of quenching media; oil temperature 60 ~ 80 , the water temperature below 30 , when the quenching amount is large and the cooling medium temperature increases, it should add cooling quenching medium or switch to other cooling tank to cool; stir strengthen coolant; remove it in about ms + 50 .

5, carbon removal, which is caused by the raw materials residual decarburization or heating when quenching, the preventive measures are for controlled atmosphere heating, bath heating, vacuum furnace, box furnace with protective packing or oxidation coating; machining margin increase by the amount of 2 ~ 3mm.